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Sample records for air concentration limits

  1. 10 CFR Appendix B to Part 20 - Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...,” and “Water,” are applicable to the assessment and control of dose to the public, particularly in the...). Consideration of non-stochastic limits has not been included in deriving the air and water effluent... water concentrations were derived by taking the most restrictive occupational stochastic oral...

  2. 10 CFR Appendix B to Part 20 - Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...,” and “Water,” are applicable to the assessment and control of dose to the public, particularly in the...). Consideration of non-stochastic limits has not been included in deriving the air and water effluent... water concentrations were derived by taking the most restrictive occupational stochastic oral...

  3. Short-term 222Rn activity concentration changes in underground spaces with limited air exchange with the atmosphere

    NASA Astrophysics Data System (ADS)

    Fijałkowska-Lichwa, L.; Przylibski, T. A.

    2011-04-01

    The authors investigated short-time changes in 222Rn activity concentration occurring yearly in two underground tourist facilities with limited air exchange with the atmosphere. One of them is Niedźwiedzia (Bear) Cave in Kletno, Poland - a natural space equipped with locks ensuring isolation from the atmosphere. The other site is Fluorite Adit in Kletno, a section of a disused uranium mine. This adit is equipped with a mechanical ventilation system, operated periodically outside the opening times (at night). Both sites are situated within the same metamorphic rock complex, at similar altitudes, about 2 km apart. The measurements conducted revealed spring and autumn occurrence of convective air movements. In Bear Cave, this process causes a reduction in 222Rn activity concentration in the daytime, i.e. when tourists, guides and other staff are present in the cave. From the point of view of radiation protection, this is the best situation. For the rest of the year, daily concentrations of 222Rn activity in the cave are very stable. In Fluorite Adit, on the other hand, significant variations in daily 222Rn activity concentrations are recorded almost all year round. These changes are determined by the periods of activity and inactivity of mechanical ventilation. Unfortunately this is inactive in the daytime, which results in the highest values of 222Rn activity concentration at the times when tourists and staff are present in the adit. Slightly lower concentrations of radon in Fluorite Adit are recorded in the winter season, when convective air movements carry a substantial amount of radon out into the atmosphere. The incorrect usage of mechanical ventilation in Fluorite Adit results in the most unfavourable conditions in terms of radiation protection. The staff working in that facility are exposed practically throughout the year to the highest 222Rn activity concentrations, both at work (in the adit) and at home (outside their working hours). Therefore, not very well

  4. 10 CFR Appendix B to Part 20 - Annual Limits on Intake (ALIs) and Derived Air Concentrations (DACs) of Radionuclides for...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Annual Limits on Intake (ALIs) and Derived Air... Release to Sewerage B Appendix B to Part 20 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION... Hydrogen H 1 Indium In 49 Iodine I 53 Iridium Ir 77 Iron Fe 26 Krypton Kr 36 Lanthanum La 57 Lead Pb...

  5. OPERATIONAL LIMITATIONS FOR DEMOLITION OF A HIGHLY ALPHA CONTAMINATED BUILDING MODLES VERSUS MEASURED AIR & SURFACE ACTIVITY CONCENTRATIONS

    SciTech Connect

    LLOYD, E.R.

    2006-11-02

    The demolition of a facility historically used for processing and handling transuranic materials is considered. Residual alpha emitting radionuclide contamination poses an exposure hazard if released to the local environment during the demolition. The process of planning for the demolition of this highly alpha contaminated building, 232-Z, included a predemolition modeling analysis of potential exposures. Estimated emission rates were used as input to an air dispersion model to estimate frequencies of occurrence of peak air and surface exposures. Postdemolition modeling was also conducted, based on the actual demolition schedule and conditions. The modeling results indicated that downwind deposition is the main operational limitation for demolition of a highly alpha-contaminated building. During the demolition of 232-Z, airborne radiation and surface contamination were monitored. The resultant non-detect monitoring results indicate a significant level of conservatism in the modeled results. This comparison supports the use of more realistic assumption in the estimating emission rates. The resultant reduction in modeled levels of potential exposures has significant implications in terms of the projected costs of demolition of such structures.

  6. Summary of Dissolved Concentration Limits

    SciTech Connect

    Yueting Chen

    2001-06-11

    According to the Technical Work Plan titled Technical Work Plan for Waste Form Degradation Process Model Report for SR (CRWMS M&O 2000a), the purpose of this study is to perform abstractions on solubility limits of radioactive elements based on the process-level information and thermodynamic databases provided by Natural Environment Program Operations (NEPO) and Waste Package Operations (WPO). The scope of this analysis is to produce solubility limits as functions, distributions, or constants for all transported radioactive elements identified by the Performance Assessment Operations (PAO) radioisotope screening. Results from an expert elicitation for solubility limits of most radioactive elements were used in the previous Total System Performance Assessments (TSPAs). However, the elicitation conducted in 1993 does not meet the criteria set forth by the U.S. Nuclear Regulatory Commission (NRC) due to lack of documentation and traceability (Kotra et al. 1996, Section 3). Therefore, at the Waste Form Abstraction Workshop held on February 2-4, 1999, at Albuquerque, New Mexico, the Yucca Mountain Site Characterization Project (YMP) decided to develop geochemical models to study solubility for the proposed Monitored Geologic Repository. WPO/NEPO is to develop process-level solubility models, including review and compilation of relevant thermodynamic data. PAO's responsibility is to perform abstractions based on the process models and chemical conditions and to produce solubility distributions or response surfaces applicable to the proposed repository. The results of this analysis and conceptual model will feed the performance assessment for Total System Performance Assessment--Site Recommendation (TSPA-SR) and Total System Performance Assessment--License Application (TSPA-LA), and to the Waste Form Degradation Process Model Report section on concentration limits.

  7. Reducing indoor air formaldehyde concentrations

    SciTech Connect

    Meyer, B.; Hermanns, K.

    1985-08-01

    Urea-formaldehyde resin bonded particle board, medium density fiberboard and plywood paneling are used as flooring, wall paneling, for cabinet work and in furniture, and are present in almost every office, home and public building. If large quantities of these products are used in poorly ventilated spaces, high manufacturing quality control is necessary to avoid problems of latent formaldehyde release. Indoor air formaldehyde concentrations depend on the nature of the product, the product surface to air volume (loading) factor, temperature, humidity, age and product emission rates. Standard test methods are now available for measuring product emission rates that make it possible to predict the performance of UF-bonded pressed wood materials if use conditions and environmental parameters are known. Recent modifications in adhesive and board manufacturing parameters have made it possible to reduce formaldehyde emission significantly, and UF-bonded wood products are now capable of meeting indoor air quality standard levels of 0.1 ppm under almost all customary loading conditions.

  8. Long-memory property in air pollutant concentrations

    NASA Astrophysics Data System (ADS)

    Chelani, Asha

    2016-05-01

    In the present paper, long-memory in air pollutant concentrations is reviewed and outcome of the past studies is analyzed to provide the possible mechanism behind temporal evolution of air pollutant concentrations. It is observed that almost all the studies show air pollutant concentrations over time possess persistence up to a certain limit. Self-organized criticality of air pollution, multiplicative process of pollutant concentrations, and uniformity in emission sources leading to self-organized criticality are few of the phenomena behind the persistent property of air pollutant concentrations. The self-organized criticality of air pollution is linked to atmosphere's self-cleansing mechanism. This demonstrates that inspite of increasing anthropogenic emissions, self-organized criticality of air pollution is sustained and has low influence of human interventions. In the future, this property may, however, be perturbed due to continuous air pollution emissions, which may influence the accuracy in predictions.

  9. INDOOR AIR CONCENTRATION UNIT CONVERSIONS

    EPA Science Inventory

    Migration of volatile chemicals from the subsurface into overlying buildings is called vapor intrusion (VI). Volatile organic chemicals in contaminated soils or groundwater can emit vapors, which can migrate through subsurface soils and may enter the indoor air of overlying buil...

  10. Limiting values of radionuclide intake and air concentration and dose conversion factors for inhalation, submersion, and ingestion: Federal guidance report No. 11

    SciTech Connect

    Eckerman, K.F.; Wolbarst, A.B.; Richardson, A.C.B.

    1988-09-01

    Radiation protection programs for workers are based, in the United States, on a hierarchy of limitations stemming from Federal guidance approved by the President. This guidance, which consists of principles, policies, and numerical primary guides, is used by Federal agencies as the basis for developing and implementing their own regulatory standards. The primary guides are usually expressed in terms of limiting doses to workers. The protection of workers against taking radioactive materials into the body, however, is accomplished largely through the use of regulations based on derived guides expressed in terms of quantities or concentrations of radionuclides. The values of these derived guides are chosen so as to assure that workers in work environments that conform to them are unlikely to receive radiation doses that exceed the primary guides. The purpose of the present report is to set forth derived guides that are consistent with current Federal radiation protection guidance. They are intended to serve as the basis for regulations setting upper bounds on the inhalation and ingestion of, and submersion in, radioactive materials in the workplace. The report also includes tables of exposure-to-dose conversion factors, for general use in assessing average individual committed doses in any population that is adequately characterized by Reference Man. 38 refs.

  11. Limit of concentration for cylindrical concentrators under extended light sources.

    PubMed

    Miñano, J C; Luque, A

    1983-08-15

    Cylindrical concentrators illuminated by an extended source with an arbitrary distribution of radiance are analyzed taking into account basic properties derived from the Fermat principle and not from the specific concentrator shape. The upper limit of concentration achievable with this type of concentrator is obtained and it is found to be lower than that of general (3-D) concentrators. Cylindrical compound parabolic concentrators are analyzed in the light of this theory, and it is shown that they achieve the highest optical concentration possible for a cylindrical concentrator. PMID:18196152

  12. Pushing concentration of stationary solar concentrators to the limit.

    PubMed

    Winston, Roland; Zhang, Weiya

    2010-04-26

    We give the theoretical limit of concentration allowed by nonimaging optics for stationary solar concentrators after reviewing sun- earth geometry in direction cosine space. We then discuss the design principles that we follow to approach the maximum concentration along with examples including a hollow CPC trough, a dielectric CPC trough, and a 3D dielectric stationary solar concentrator which concentrates sun light four times (4x), eight hours per day year around. PMID:20607887

  13. Pushing concentration of stationary solar concentrators to the limit.

    PubMed

    Winston, Roland; Zhang, Weiya

    2010-04-26

    We give the theoretical limit of concentration allowed by nonimaging optics for stationary solar concentrators after reviewing sun-earth geometry in direction cosine space. We then discuss the design principles that we follow to approach the maximum concentration along with examples including a hollow CPC trough, a dielectric CPC trough, and a 3D dielectric stationary solar concentrator which concentrates sun light four times (4x), eight hours per day year around. PMID:20588575

  14. 40 CFR 264.94 - Concentration limits.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 264.94 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Releases From Solid Waste Management Units § 264.94 Concentration limits. (a) The Regional Administrator...

  15. Observations on using inside air concentrations as a predictor of outside air concentrations

    SciTech Connect

    Hawkley, Gavin; Whicker, Jeffrey; Harris, Jason

    2015-04-01

    Here, excavations of radiological material were performed within confined structures with known operational parameters, such as a filtered exhaust system with known filtration efficiency. Given the known efficiency, the assumption could be made that the air concentrations of radioactivity measured outside the structure would be proportional to the air concentrations measured inside the structure. To investigate this assumption, the inside concentration data was compared with the outside concentration data. The correlation of the data suggested that the inside concentrations were not a good predictor of the outside concentrations. This poor correlation was deemed to be a result of operational unknowns within the structures.

  16. Observations on using inside air concentrations as a predictor of outside air concentrations

    DOE PAGES

    Hawkley, Gavin; Whicker, Jeffrey; Harris, Jason

    2015-04-01

    Here, excavations of radiological material were performed within confined structures with known operational parameters, such as a filtered exhaust system with known filtration efficiency. Given the known efficiency, the assumption could be made that the air concentrations of radioactivity measured outside the structure would be proportional to the air concentrations measured inside the structure. To investigate this assumption, the inside concentration data was compared with the outside concentration data. The correlation of the data suggested that the inside concentrations were not a good predictor of the outside concentrations. This poor correlation was deemed to be a result of operational unknownsmore » within the structures.« less

  17. Flammability limits of dusts: Minimum inerting concentrations

    SciTech Connect

    Dastidar, A.G.; Amyotte, P.R.; Going, J.; Chatrathi, K.

    1999-05-01

    A new flammability limit parameter has been defined as the Minimum Inerting Concentration (MIC). This is the concentration of inertant required to prevent a dust explosion regardless of fuel concentration. Previous experimental work at Fike in a 1-m{sup 3} spherical chamber has shown this flammability limit to exist for pulverized coal dust and cornstarch. In the current work, inerting experiments with aluminum, anthraquinone and polyethylene dusts as fuels were performed, using monoammonium phosphate and sodium bicarbonate as inertants. The results show that an MIC exists only for anthraquinone inerted with sodium bicarbonate. The other combustible dust and inertant mixtures did not show a definitive MIC, although they did show a strong dependence between inerting level and suspended fuel concentration. As the fuel concentration increased, the amount of inertant required to prevent an explosion decreased. Even though a definitive MIC was not found for most of the dusts an effective MIC can be estimated from the data. The use of MIC data can aid in the design of explosion suppression schemes.

  18. Scavenging ratios based on inflow air concentrations

    SciTech Connect

    Davis, W.E.; Dana, M.T.; Lee, R.N.; Slinn, W.G.N.; Thorp, J.M.

    1991-07-01

    Scavenging ratios were calculated from field measurements made during April 1985. Event precipitation samples were collected at the surface, but air chemistry measurements in the air mass feeding the precipitation were made from an aircraft. In contrast, ratios calculated in previous studies have used air concentration and precipitation chemistry data from only surface measurements. Average scavenging ratios were calculated for SO{sub 4}{sup 2{minus}}, NO{sub 3}{sup {minus}}, NH{sub 4}{sup +}, total sulfate, total nitrate, and total ammonium for 5 events; the geometric mean of these scavenging ratios were 8.5 {times} 10{sup 5}, 5.6 {times} 10{sup 6}, 4.3 {times} 10{sup 5}, 3.4 {times} 10{sup 5}, 2.4 {times} 10{sup 6}, and 9.7 {times} 10{sup 4}, respectively. These means are similar to but less variable than previous ratios formed using only surface data.

  19. DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS

    SciTech Connect

    NA

    2004-11-22

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 elements with radioactive isotopes (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium) important to calculated dose. Model outputs for uranium, plutonium, neptunium, thorium, americium, and protactinium are in the form of tabulated functions with pH and log (line integral) CO{sub 2} as independent variables, plus one or more uncertainty terms. The solubility limits for the remaining elements are either in the form of distributions or single values. The output data from this report are fundamental inputs for Total System Performance Assessment for the License Application (TSPA-LA) to determine the estimated release of these elements from waste packages and the engineered barrier system. Consistent modeling approaches and environmental conditions were used to develop solubility models for all of the actinides. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, and activity coefficients have been quantified or otherwise addressed.

  20. Indoor Air VOC Concentrations in Suburban and Rural New Jersey

    PubMed Central

    WEISEL, CLIFFORD P.; ALIMOKHTARI, SHAHNAZ; SANDERS, PAUL F.

    2014-01-01

    Indoor VOC air concentrations of many compounds are higher than outdoor concentrations due to indoor sources. However, most studies have measured residential indoor air in urban centers so the typical indoor air levels in suburban and rural regions have not been well characterized. Indoor VOC air concentrations were measured in 100 homes in suburban and rural areas in NJ to provide background levels for investigations of the impact from subsurface contamination sources. Of the 57 target compounds, 23 were not detected in any of the homes, and 14 compounds were detected in at least 50% of the homes with detection limits of ~1 μg/m3. The common compounds identified included aromatic and aliphatic hydrocarbons from mobile sources, halogenated hydrocarbons commonly used in consumer products or from chlorinated drinking water, acetone and 2-butanone emitted from cosmetic products, and Freons. Typical concentrations were in the low μg/m3 range, though values of tens, hundreds or even thousands of μg/m3 were measured in individual homes in which activities related to specific sources of VOCs were reported. Compounds with known similar sources were highly correlated. The levels observed are consistent with concentrations found in the air of urban homes. PMID:19068799

  1. Indoor air VOC concentrations in suburban and rural New Jersey.

    PubMed

    Weisel, Clifford P; Alimokhtari, Shahnaz; Sanders, Paul F

    2008-11-15

    Indoor VOC air concentrations of many compounds are higher than outdoor concentrations due to indoor sources. However, most studies have measured residential indoor air in urban centers so the typical indoor air levels in suburban and rural regions have not been well characterized. Indoor VOC air concentrations were measured in 100 homes in suburban and rural areas in NJ to provide background levels for investigations of the impact from subsurface contamination sources. Of the 57 target compounds, 23 were not detected in any of the homes, and 14 compounds were detected in at least 50% of the homes with detection limits of approximately 1 microg/m3. The common compounds identified included aromatic and aliphatic hydrocarbons from mobile sources, halogenated hydrocarbons commonly used in consumer products or from chlorinated drinking water, acetone and 2-butanone emitted from cosmetic products, and Freons. Typical concentrations were in the low microg/m3 range, though values of tens, hundreds or even thousands of microg/m3 were measured in individual homes in which activities related to specific sources of VOCs were reported. Compounds with known similar sources were highly correlated. The levels observed are consistent with concentrations found in the air of urban homes. PMID:19068799

  2. DISSOLVED CONCENTRATION LIMITS OF RADIOACTIVE ELEMENTS

    SciTech Connect

    P. Bernot

    2005-07-13

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of elements with radioactive isotopes under probable repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, field measurements, and laboratory experiments. The scope of this activity is to predict dissolved concentrations or solubility limits for elements with radioactive isotopes (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium) relevant to calculated dose. Model outputs for uranium, plutonium, neptunium, thorium, americium, and protactinium are provided in the form of tabulated functions with pH and log fCO{sub 2} as independent variables, plus one or more uncertainty terms. The solubility limits for the remaining elements are either in the form of distributions or single values. Even though selection of an appropriate set of radionuclides documented in Radionuclide Screening (BSC 2002 [DIRS 160059]) includes actinium, transport of Ac is not modeled in the total system performance assessment for the license application (TSPA-LA) model because of its extremely short half-life. Actinium dose is calculated in the TSPA-LA by assuming secular equilibrium with {sup 231}Pa (Section 6.10); therefore, Ac is not analyzed in this report. The output data from this report are fundamental inputs for TSPA-LA used to determine the estimated release of these elements from waste packages and the engineered barrier system. Consistent modeling approaches and environmental conditions were used to develop solubility models for the actinides discussed in this report. These models cover broad ranges of environmental conditions so they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, and activity coefficients have been quantified or

  3. Toxicity Data to Determine Refrigerant Concentration Limits

    SciTech Connect

    Calm, James M.

    2000-09-30

    This report reviews toxicity data, identifies sources for them, and presents resulting exposure limits for refrigerants for consideration by qualified parties in developing safety guides, standards, codes, and regulations. It outlines a method to calculate an acute toxicity exposure limit (ATEL) and from it a recommended refrigerant concentration limit (RCL) for emergency exposures. The report focuses on acute toxicity with particular attention to lethality, cardiac sensitization, anesthetic and central nervous system effects, and other escape-impairing effects. It addresses R-11, R-12, R-22, R-23, R-113, R-114, R-116, R-123, R-124, R-125, R-134, R-134a, R-E134, R-141b, R-142b, R-143a, R-152a, R-218, R-227ea, R-236fa, R-245ca, R-245fa, R-290, R-500, R-502, R-600a, R-717, and R-744. It summarizes additional data for R-14, R-115, R-170 (ethane), R-C318, R-600 (n-butane), and R-1270 (propylene) to enable calculation of limits for blends incorporating them. The report summarizes the data a nd related safety information, including classifications and flammability data. It also presents a series of tables with proposed ATEL and RCL concentrations-in dimensionless form and the latter also in both metric (SI) and inch-pound (IP) units of measure-for both the cited refrigerants and 66 zerotropic and azeotropic blends. They include common refrigerants, such as R-404A, R-407C, R-410A, and R-507A, as well as others in commercial or developmental status. Appendices provide profiles for the cited single-compound refrigerants and for R-500 and R-502 as well as narrative toxicity summaries for common refrigerants. The report includes an extensive set of references.

  4. Dissolved Concentration Limits of Radioactive Elements

    SciTech Connect

    Y. Chen; E.R. Thomas; F.J. Pearson; P.L. Cloke; T.L. Steinborn; P.V. Brady

    2003-06-20

    The purpose of this study is to evaluate dissolved concentration limits (also referred to as solubility limits) of radioactive elements under possible repository conditions, based on geochemical modeling calculations using geochemical modeling tools, thermodynamic databases, and measurements made in laboratory experiments and field work. The scope of this modeling activity is to predict dissolved concentrations or solubility limits for 14 radioactive elements (actinium, americium, carbon, cesium, iodine, lead, neptunium, plutonium, protactinium, radium, strontium, technetium, thorium, and uranium), which are important to calculated dose. Model outputs are mainly in the form of look-up tables plus one or more uncertainty terms. The rest are either in the form of distributions or single values. The results of this analysis are fundamental inputs for total system performance assessment to constrain the release of these elements from waste packages and the engineered barrier system. Solubilities of plutonium, neptunium, uranium, americium, actinium, thorium, protactinium, lead, and radium have been re-evaluated using the newly updated thermodynamic database (Data0.ymp.R2). For all of the actinides, identical modeling approaches and consistent environmental conditions were used to develop solubility models in this revision. These models cover broad ranges of environmental conditions so that they are applicable to both waste packages and the invert. Uncertainties from thermodynamic data, water chemistry, temperature variation, activity coefficients, and selection of solubility controlling phase have been quantified or otherwise addressed. Moreover, a new blended plutonium solubility model has been developed in this revision, which gives a mean solubility that is three orders of magnitude lower than the plutonium solubility model used for the Total System Performance Assessment for the Site Recommendation. Two alternative neptunium solubility models have also been

  5. 14 CFR 93.319 - Commercial air tour limitations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Commercial air tour limitations. 93.319... (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SPECIAL AIR TRAFFIC RULES Special Flight Rules in the Vicinity of Grand Canyon National Park, AZ § 93.319 Commercial air tour limitations. (a) Unless...

  6. Colloid-Associated Radionuclide Concentration Limits: ANL

    SciTech Connect

    C. Mertz

    2000-12-21

    The purpose and scope of this report is to describe the analysis of available colloidal data from waste form corrosion tests at Argonne National Laboratory (ANL) to extract characteristics of these colloids that can be used in modeling their contribution to the source term for sparingly soluble radioelements (e.g., Pu). Specifically, the focus is on developing a useful description of the following waste form colloid characteristics: (1) composition, (2) size distribution, and (3) quantification of the rate of waste form colloid generation. The composition and size distribution information are intended to support analysis of the potential transport of the sparingly soluble radionuclides associated with the waste form colloids. The rate of colloid generation is intended to support analysis of the waste form colloid-associated radionuclide concentrations. In addressing the above characteristics, available data are interpreted to address mechanisms controlling colloid formation and stability. This report was developed in accordance with the ''Technical Work Plan for Waste Form Degradation Process Model Report for SR'' (CRWMS M&O 2000). Because the end objective is to support the source term modeling we have organized the conclusions into two categories: (1) data analysis conclusions and (2) recommendations for colloid source term modeling. The second category is included to facilitate use of the conclusions from the data analysis in the abstraction of a colloid source term model. The data analyses and conclusions that are presented in this report are based on small-scale laboratory tests conducted on a limited number of waste glass compositions and spent fuel types.

  7. Air radon concentration decrease in a waste water treatment plant.

    PubMed

    Juste, B; Ortiz, J; Verdú, G; Martorell, S

    2015-06-01

    (222)Rn is a naturally occurring gas created from the decay of (226)Ra. The long-term health risk of breathing radon is lung cancer. One particular place where indoor radon concentrations can exceed national guidelines is in wastewater treatment plants (WWTPs) where treatment processes may contribute to ambient airborne concentrations. The aim of this paper was to study the radon concentration decrease after the application of corrective measures in a Spanish WWTP. According to first measures, air radon concentration exceeded International Commission Radiologica1 Protection (ICRP) normative (recommends intervention between 400 and 1000 Bq m(-3)). Therefore, the WWTP improved mechanical forced ventilation to lower occupational exposure. This measure allowed to increase the administrative controls, since the limitation of workers access to the plant changed from 2 h d(-1) (considering a maximum permissible dose of 20 mSv y(-1) averaged over 5 y) to 7 h d(-1).

  8. Air radon concentration decrease in a waste water treatment plant.

    PubMed

    Juste, B; Ortiz, J; Verdú, G; Martorell, S

    2015-06-01

    (222)Rn is a naturally occurring gas created from the decay of (226)Ra. The long-term health risk of breathing radon is lung cancer. One particular place where indoor radon concentrations can exceed national guidelines is in wastewater treatment plants (WWTPs) where treatment processes may contribute to ambient airborne concentrations. The aim of this paper was to study the radon concentration decrease after the application of corrective measures in a Spanish WWTP. According to first measures, air radon concentration exceeded International Commission Radiologica1 Protection (ICRP) normative (recommends intervention between 400 and 1000 Bq m(-3)). Therefore, the WWTP improved mechanical forced ventilation to lower occupational exposure. This measure allowed to increase the administrative controls, since the limitation of workers access to the plant changed from 2 h d(-1) (considering a maximum permissible dose of 20 mSv y(-1) averaged over 5 y) to 7 h d(-1). PMID:25971342

  9. Minanre Gas Concentrators For Air Sampling

    SciTech Connect

    Dr. Seung Ho Hong

    2001-03-01

    The goal of this project was to demonstrate the feasibility of a compact, lightweight, gas-sampling device with rapid-cycle-time characteristics. The highlights of our Phase I work include: (1) Demonstration of a compact gas sampler with integrated heater. This device has an order of magnitude greater adsorption capacity and much faster heating/cooling times than commercial sorbent tubes. (2) Completion of computational fluid dynamics modeling of the gas sampler to determine airflow characteristics for various design options. These modeling efforts guided the development and testing of the Mesochannel Gas Sampler prototype. (3) Testing of the Mesochannel Gas Sampler in parallel with tests of two packed-bed samplers. These tests showed the Mesochannel Gas Sampler represents a substantial improvement compared with the packed-bed approach. Our mesochannel heat-exchanger/adsorber architecture allows very efficient use of adsorbent mass, high adsorbent loadings, and very low pressure drop, which makes possible very high air-sampling rates using a simple, low-power fan. This device is well-suited for collecting samples of trace-level contaminants. The integrated heater, which forms the adsorbent-coated mesochannel walls, allows direct heating of the adsorbent and results in very rapid desorption of the adsorbed species. We believe the Mesochannel Gas Sampler represents a promising technology for the improvement of trace-contaminant detection limits. In our Phase II proposal, we outline several improvements to the gas sampler that will further improve its performance.

  10. Concentrated Solar Air Conditioning for Buildings Project

    NASA Technical Reports Server (NTRS)

    McLaughlin, Rusty

    2010-01-01

    This slide presentation reviews project to implement the use of solar power to provide air conditioning for NASA buildings. Included is an overall conceptual schematic, and an diagram of the plumbing and instrumentation for the project. The use of solar power to power air conditioning in buildings, particularly in the Southwest, could save a significant amount of money. DOD studies have concluded that air conditioning accounts for 30-60% of total energy expenditures.

  11. 30 CFR 33.33 - Allowable limits of dust concentration.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Allowable limits of dust concentration. 33.33... MINES Test Requirements § 33.33 Allowable limits of dust concentration. (a) The concentration of dust determined by the control sample shall be subtracted from the average concentration of dust determined by...

  12. 30 CFR 33.33 - Allowable limits of dust concentration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Allowable limits of dust concentration. 33.33... MINES Test Requirements § 33.33 Allowable limits of dust concentration. (a) The concentration of dust determined by the control sample shall be subtracted from the average concentration of dust determined by...

  13. 30 CFR 33.33 - Allowable limits of dust concentration.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Allowable limits of dust concentration. 33.33... MINES Test Requirements § 33.33 Allowable limits of dust concentration. (a) The concentration of dust determined by the control sample shall be subtracted from the average concentration of dust determined by...

  14. 14 CFR 93.319 - Commercial air tour limitations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 2 2014-01-01 2014-01-01 false Commercial air tour limitations. 93.319 Section 93.319 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SPECIAL AIR TRAFFIC RULES Special Flight Rules in the Vicinity of Grand Canyon National Park, AZ...

  15. 40 CFR Appendix IV to Part 266 - Reference Air Concentrations*

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Reference Air Concentrations* IV Appendix IV to Part 266 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES... MANAGEMENT FACILITIES Pt. 266, App. IV Appendix IV to Part 266—Reference Air Concentrations* Constituent...

  16. 30 CFR 33.33 - Allowable limits of dust concentration.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., EVALUATION, AND APPROVAL OF MINING PRODUCTS DUST COLLECTORS FOR USE IN CONNECTION WITH ROCK DRILLING IN COAL MINES Test Requirements § 33.33 Allowable limits of dust concentration. (a) The concentration of dust... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Allowable limits of dust concentration....

  17. Air Pollution in China: Mapping of Concentrations and Sources

    PubMed Central

    Rohde, Robert A.; Muller, Richard A.

    2015-01-01

    China has recently made available hourly air pollution data from over 1500 sites, including airborne particulate matter (PM), SO2, NO2, and O3. We apply Kriging interpolation to four months of data to derive pollution maps for eastern China. Consistent with prior findings, the greatest pollution occurs in the east, but significant levels are widespread across northern and central China and are not limited to major cities or geologic basins. Sources of pollution are widespread, but are particularly intense in a northeast corridor that extends from near Shanghai to north of Beijing. During our analysis period, 92% of the population of China experienced >120 hours of unhealthy air (US EPA standard), and 38% experienced average concentrations that were unhealthy. China’s population-weighted average exposure to PM2.5 was 52 μg/m3. The observed air pollution is calculated to contribute to 1.6 million deaths/year in China [0.7–2.2 million deaths/year at 95% confidence], roughly 17% of all deaths in China. PMID:26291610

  18. Air Pollution in China: Mapping of Concentrations and Sources.

    PubMed

    Rohde, Robert A; Muller, Richard A

    2015-01-01

    China has recently made available hourly air pollution data from over 1500 sites, including airborne particulate matter (PM), SO2, NO2, and O3. We apply Kriging interpolation to four months of data to derive pollution maps for eastern China. Consistent with prior findings, the greatest pollution occurs in the east, but significant levels are widespread across northern and central China and are not limited to major cities or geologic basins. Sources of pollution are widespread, but are particularly intense in a northeast corridor that extends from near Shanghai to north of Beijing. During our analysis period, 92% of the population of China experienced >120 hours of unhealthy air (US EPA standard), and 38% experienced average concentrations that were unhealthy. China's population-weighted average exposure to PM2.5 was 52 μg/m3. The observed air pollution is calculated to contribute to 1.6 million deaths/year in China [0.7-2.2 million deaths/year at 95% confidence], roughly 17% of all deaths in China. PMID:26291610

  19. Daily variations of indoor air-ion and radon concentrations.

    PubMed

    Kolarz, P M; Filipović, D M; Marinković, B P

    2009-11-01

    Air-ions and radon are two atmospheric trace constituents which have two opposite effects on human health: the ions are beneficial, and radon gas is potentially lethal as it increases the risk of lung cancer. In the lower troposphere, radon is the most important generator of the air-ions. Ionization by cosmic rays and radioactive minerals is almost constant in daily cycles, and variation of air-ion concentrations is attributed to changes of the radon activity. Air-ion and radon concentrations in outdoor and indoor space and their vertical gradients in residential buildings were measured. Gerdien type air-ion detector "CDI-06" made in our laboratory and radon monitor "RAD7" were utilized for these measurements. Correlation coefficient between positive air-ion and Rn indoor concentrations was approximately 0.7. Outdoor and indoor peak values were simultaneous while vertical gradient of concentrations in indoor measurements was evident. The indoor experiments showed that positive air-ion concentration could be an alternative method of radon activity concentration evaluation. PMID:19700332

  20. 14 CFR 93.319 - Commercial air tour limitations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Vicinity of Grand Canyon National Park, AZ § 93.319 Commercial air tour limitations. (a) Unless excepted... 119 for part 121 or 135 operations may conduct more commercial air tours in the Grand Canyon National... conformance with the routes and airspace authorizations as specified in its Grand Canyon National Park...

  1. 14 CFR 93.319 - Commercial air tour limitations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Vicinity of Grand Canyon National Park, AZ § 93.319 Commercial air tour limitations. (a) Unless excepted... 119 for part 121 or 135 operations may conduct more commercial air tours in the Grand Canyon National... conformance with the routes and airspace authorizations as specified in its Grand Canyon National Park...

  2. 14 CFR 93.319 - Commercial air tour limitations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Vicinity of Grand Canyon National Park, AZ § 93.319 Commercial air tour limitations. (a) Unless excepted... 119 for part 121 or 135 operations may conduct more commercial air tours in the Grand Canyon National... conformance with the routes and airspace authorizations as specified in its Grand Canyon National Park...

  3. Concentrations of selected contaminants in cabin air of airbus aircrafts.

    PubMed

    Dechow, M; Sohn, H; Steinhanses, J

    1997-07-01

    The concentrations of selected air quality parameters in aircraft cabins were investigated including particle numbers in cabin air compared to fresh air and recirculation air, the microbiological contamination and the concentration of volatile organic compounds (VOC). The Airbus types A310 of Swissair and A340 of Lufthansa were used for measurements. The particles were found to be mainly emitted by the passengers, especially by smokers. Depending on recirculation filter efficiency the recirculation air contained a lower or equal amount of particles compared to the fresh air, whereas the amount of bacteria exceeded reported concentrations within other indoor spaces. The detected species were mainly non-pathogenic, with droplet infection over short distances identified as the only health risk. The concentration of volatile organic compounds (VOC) were well below threshold values. Ethanol was identified as the compound with the highest amount in cabin air. Further organics were emitted by the passengers--as metabolic products or by smoking--and on ground as engine exhaust (bad airport air quality). Cleaning agents may be the source of further compounds.

  4. CONCENTRATIONS OF TOXIC AIR POLLUTANTS IN THE U.S. SIMULATED BY AN AIR QUALITY MODEL

    EPA Science Inventory

    As part of the US National Air Toxics Assessment, we have applied the Community Multiscale Air Quality Model, CMAQ, to study the concentrations of twenty gas-phase, toxic, hazardous air pollutants (HAPs) in the atmosphere over the continental United States. We modified the Carbo...

  5. Ambient air concentrations of particulate matter from passenger cars.

    PubMed

    Schürmann, D

    1989-01-01

    Using our measurement results on particulate emissions from passenger cars we have calculated ambient air concentrations for various US and European scenarios. This was carried out with the help of mathematical dispersion models for different traffic situations including street canyons and motorways. We have been very conservative in our choice of the scenarios, i.e. we have always used situations in which there are very high stress levels (e.g. constantly high traffic flow instead of average traffic flow). Finally, the thus determined air concentrations are compared with the corresponding air quality standard available from the literature.

  6. Ambient air concentrations of particulate matter from passenger cars.

    PubMed

    Schürmann, D

    1989-01-01

    Using our measurement results on particulate emissions from passenger cars we have calculated ambient air concentrations for various US and European scenarios. This was carried out with the help of mathematical dispersion models for different traffic situations including street canyons and motorways. We have been very conservative in our choice of the scenarios, i.e. we have always used situations in which there are very high stress levels (e.g. constantly high traffic flow instead of average traffic flow). Finally, the thus determined air concentrations are compared with the corresponding air quality standard available from the literature. PMID:2484034

  7. Exceedance of PM10 and ozone concentration limits in Germany - Spatial variability and influence of climate

    NASA Astrophysics Data System (ADS)

    Heidenreich, Majana; Bernhofer, Christian

    2014-05-01

    High concentrations of particulate matter (PM) and ground-level ozone (O3) have negative impacts on human health, e.g., increased risk of respiratory disease, and the environment. European Union (EU) air policy and air quality standards led to continuously reduced air pollution problems in recent decades. Nevertheless, the limit values for PM10 (particles with diameter of 10 micrometers or less) and ozone - defined by the directive 2008/50/EC of the European Parliament - are still exceeded frequently. Poor air quality and the exceedance of limits result mainly from the combination of high emissions and unfavourable weather conditions. Datasets from German monitoring stations are used to describe the spatial and temporal variability of the exceedance of concentration limits for PM10 and ozone for the federal states of Germany. Time series are analysed for the period 2000-2012 for PM10 and for the period 1990-2012 for ozone. Furthermore, the influence of weather patterns on the exceedance of concentration limits on a regional scale was investigated. Here, the "objective weather types" of the German Weather Service were used. As expected, for most regions anticyclonic weather types (with a negative cyclonality index for the two levels 950 and 500 hPa) show a high frequency on exeedance days, both for PM10 and ozone. The results could contribute to estimate the future exceedance frequency of concentration limits and to develop possible countermeasures.

  8. Ultralow Concentration Mercury Treatment Using Chemical Reduction and Air Stripping

    SciTech Connect

    Looney, B.B.

    2001-05-21

    Field, laboratory and engineering data confirmed the efficacy of chemical reduction and air stripping as an ultralow concentration mercury treatment concept for water containing Hg(II). The simple process consists of dosing the water with low levels of stannous chloride (Sn(II)) to cover the mercury to Hg degrees. This mercury species can easily be removed from the water by air stripping or sparging.

  9. Concentrations of propoxur in air following repeated indoor applications.

    PubMed

    Miller, C W; Shafik, T M

    1974-01-01

    The insecticide propoxur was applied as 2 non-overlapping bands approximately 1 m wide to the interior of houses in El Salvador once every 35 days for a period of 9 months. Air samples were collected from the interior of the houses once every seventh day during the entire period. In the study area, air temperatures remain relatively constant, while rainfall varies seasonally. It was found that volatilization of propoxur, as determined by the amounts detectable in air, represented release of the chemical from the treated surface and that the volatilization process was most influenced by the amount of moisture present in the air. Higher air concentrations of propoxur occurred during periods of high relative humidity than in periods of low relative humidity. The principles involved in this process and its bearing on the value of propoxur in malaria control programmes are discussed.

  10. Ozone concentrations in air flowing into New York State

    NASA Astrophysics Data System (ADS)

    Aleksic, Nenad; Kent, John; Walcek, Chris

    2016-09-01

    Ozone (O3) concentrations measured at Pinnacle State Park (PSPNY), very close to the southern border of New York State, are used to estimate concentrations in air flowing into New York. On 20% of the ozone season (April-September) afternoons from 2004 to 2015, mid-afternoon 500-m back trajectories calculated from PSPNY cross New York border from the south and spend less than three hours in New York State, in this area of negligible local pollution emissions. One-hour (2p.m.-3p.m.) O3 concentrations during these inflowing conditions were 46 ± 13 ppb, and ranged from a minimum of 15 ppb to a maximum of 84 ppb. On average during 2004-2015, each year experienced 11.8 days with inflowing 1-hr O3 concentrations exceeding 50 ppb, 4.3 days with O3 > 60 ppb, and 1.5 days had O3 > 70 ppb. During the same period, 8-hr average concentrations (10a.m. to 6p.m.) exceeded 50 ppb on 10.0 days per season, while 3.9 days exceeded 60 ppb, and 70 ppb was exceeded 1.2 days per season. Two afternoons of minimal in-state emission influences with high ozone concentrations were analyzed in more detail. Synoptic and back trajectory analysis, including comparison with upwind ozone concentrations, indicated that the two periods were characterized as photo-chemically aged air containing high inflowing O3 concentrations most likely heavily influenced by pollution emissions from states upwind of New York including Pennsylvania, Tennessee, West Virginia, and Ohio. These results suggest that New York state-level attempts to comply with National Ambient Air Quality Standards by regulating in-state O3 precursor NOx and organic emissions would be very difficult, since air frequently enters New York State very close to or in excess of Federal Air Quality Standards.

  11. Microstructured light guides overcoming the two-dimensional concentration limit.

    PubMed

    Leutz, Ralf; Ries, Harald

    2005-11-10

    Light guides are employed to homogenize an illumination distribution, to translate cross-sectional beam shapes, and to provide concentration. Microstructures enhance the performance of light guides based on the selective mixing of direction vector components in the two-dimensional phase space (etendue) that is perpendicular to the system's optical axis. For linear concentrators we find that the microstructured light guide beats the two-dimensional concentration limit and roughly allows for a three-dimensional concentration ratio. This result is verified in simulation and experiment.

  12. Spectra of concentration of air pollution for turbulent convection

    SciTech Connect

    Patel, S.R.

    1996-12-31

    Very recently the study of formation and destruction of photochemical smog is increasing at both small and large scale. Also the transport of chemical species through the Planetary Boundary Layer (PBL) of the atmosphere is a key of the global change problem and will have to be parameterized more reliably than in the past. Further, in the air pollution modeling, the usual practice of neglecting the concentration correlation in the atmospheric photochemical reaction has recently been recognized as a source of serious error. So, it is important to study the various aspects of the concentration fluctuations (of air pollution) with chemical reaction. A model of the spectrum of concentration of air pollution with chemical reaction has been developed using the models of Hill and Hill and Clifford. The results obtained are applicable for arbitrary Schmidt number. Further, for the case of pure mixing (without chemical reaction) and the concentration replaced by temperature, the form of the spectra obtained here reduces to the form obtained by Hill and Clifford. This study also shows that, in the case of pure mixing, the concentration decays in a natural manner, but if the concentration selected is that of the chemical reactant, then the effect is that the dispersion of the concentration is much more rapid.

  13. Temperature and concentration transients in the aluminum-air battery

    SciTech Connect

    Homsy, R.V.

    1981-08-26

    Coupled conservation equations of heat and mass transfer are solved, that predict temperature and concentration of the electrolyte of an aluminum-air battery system upon start-up and shutdown. Results of recent laboratory studies investigating the crystallization kinetics and solubility of the caustic-aluminate electrolyte system are used in the predictions. Temperature and concentration start-up transients are short, while during standby conditions, temperature increases to a maximum and decreases slowly.

  14. Electron concentration distribution in a glow discharge in air flow

    NASA Astrophysics Data System (ADS)

    Mukhamedzianov, R. B.; Gaisin, F. M.; Sabitov, R. A.

    1989-04-01

    Electron concentration distributions in a glow discharge in longitudinal and vortex air flows are determined from the attenuation of the electromagnetic wave passing through the plasma using microwave probes. An analysis of the distribution curves obtained indicates that electron concentration decreases in the direction of the anode. This can be explained by charge diffusion toward the chamber walls and electron recombination and sticking within the discharge.

  15. Reference values for indoor air pollutant concentrations in new, residential buildings in Finland

    NASA Astrophysics Data System (ADS)

    Järnström, H.; Saarela, K.; Kalliokoski, P.; Pasanen, A.-L.

    Eight buildings, representing the present construction practice in Finland, were investigated to create numeric reference data for indoor air quality (IAQ) in new residential buildings. Low-emitting materials according to the "Finnish Classification of Building Materials" were used in all the buildings. The airborne volatile organic compounds (VOCs), formaldehyde, and ammonia concentrations as well as temperature, relative humidity, and the air exchange rate were determined in the newly finished buildings and after 6 and 12 months. Target values for the indoor air concentrations were not generally reached in newly finished buildings. The lowest concentration levels were measured in buildings with mechanical supply and exhaust air systems. Formaldehyde concentrations fulfilled best the target values. The TVOC concentration usually reached the S2/S3-class values within 6 months. However, the ammonia concentration remained above the S3 limit during the whole first year. The concentrations of ammonia and formaldehyde showed seasonal variations, i.e., higher concentrations were measured in summer. The concentrations of individual VOCs generally decreased most strongly during the first 6 months and the final mean concentration levels were generally less than 15 μg m -3. As the occupancy period got longer, the VOCs originating from the construction phase were increasingly replaced by new ones. Reference values based on means and on 95 percentiles are presented to facilitate interpretation of the results of measurements done to ensure that proper construction practices have been applied or to investigate IAQ problems.

  16. Measuring radon concentration in air using a diffusion cloud chamber

    NASA Astrophysics Data System (ADS)

    Cases, R.; Ros, E.; Zúñiga, J.

    2011-09-01

    Radon concentration in air is a major concern in lung cancer studies. A traditional technique used to measure radon abundance is the charcoal canister method. We propose a novel technique using a diffusion cloud chamber. This technique is simpler and can easily be used for physics demonstrations for high school and university students.

  17. Auditing and assessing air quality in concentrated feeding operations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The potential adverse effects of concentrated animal feeding operations (CAFO) on the environment are a growing concern. The air quality issues of most concerns to CAFO vary, but generally include ammonia, hydrogen sulfide, particulate matter (PM), volatile organic compounds (VOC), green house gase...

  18. Physical Limit to Concentration Sensing Amid Spurious Ligands

    NASA Astrophysics Data System (ADS)

    Mora, Thierry

    2015-07-01

    To adapt their behavior in changing environments, cells sense concentrations by binding external ligands to their receptors. However, incorrect ligands may bind nonspecifically to receptors, and when their concentration is large, this binding activity may interfere with the sensing of the ligand of interest. Here, I derive analytically the physical limit to the accuracy of concentration sensing amid a large number of interfering ligands. A scaling transition is found when the mean bound time of correct ligands is twice that of incorrect ligands. I discuss how the physical bound can be approached by a cascade of receptor states generalizing kinetic proofreading schemes.

  19. What are the costs of limiting CO2 concentrations?

    SciTech Connect

    Edmonds, James A.; Sands, Ronald D.

    2003-01-01

    The problem of stabilizing the concentration of CO2 is fundamentally different than the problem of stabilizing the concentration of a conventional pollutant or even other non-CO2 greenhouse gases. A fraction of any net anthropogenic emission is permanently committed to the atmosphere and in the very long term net anthropogenic emissions must cease if atmospheric CO2 concentrations are to be stabilized. Many of the technologies that could play a large future role in limiting cumulative carbon emissions are minor elements in the present energy system. A portfolio of technologies will be needed to address the variety of technology needs across the world's regions and over time.

  20. 30 CFR 33.33 - Allowable limits of dust concentration.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Allowable limits of dust concentration. 33.33 Section 33.33 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS DUST COLLECTORS FOR USE IN CONNECTION WITH ROCK DRILLING IN...

  1. Limits to collaborative concentration sensing in cell populations

    NASA Astrophysics Data System (ADS)

    Fancher, Sean; Mugler, Andrew

    Cells sense chemical concentrations with a precision that approaches the physical limit set by molecular diffusion. Recent experiments have vividly shown that cells can beat this limit when they communicate. We derive the physical limits to concentration sensing for cells that communicate over short distances by directly exchanging small molecules across their membranes (juxtacrine signaling), and over long distances by secreting and absorbing a diffusive messenger molecule (paracrine signaling). In the latter case, we find that the cell spacing that optimizes precision can be large, due to a tradeoff between maintaining communication strength and reducing signal cross-correlations. This leads to the surprising result that paracrine signaling allows more precise sensing than juxtacrine signaling for sufficiently large populations, even though this means that the cells are spaced far apart. We compare our results to recent experiments. This work is supported by a Grant from the Simons Foundation (376198 to A.M.).

  2. Predicting indoor pollutant concentrations, and applications to air quality management

    SciTech Connect

    Lorenzetti, David M.

    2002-10-01

    Because most people spend more than 90% of their time indoors, predicting exposure to airborne pollutants requires models that incorporate the effect of buildings. Buildings affect the exposure of their occupants in a number of ways, both by design (for example, filters in ventilation systems remove particles) and incidentally (for example, sorption on walls can reduce peak concentrations, but prolong exposure to semivolatile organic compounds). Furthermore, building materials and occupant activities can generate pollutants. Indoor air quality depends not only on outdoor air quality, but also on the design, maintenance, and use of the building. For example, ''sick building'' symptoms such as respiratory problems and headaches have been related to the presence of air-conditioning systems, to carpeting, to low ventilation rates, and to high occupant density (1). The physical processes of interest apply even in simple structures such as homes. Indoor air quality models simulate the processes, such as ventilation and filtration, that control pollutant concentrations in a building. Section 2 describes the modeling approach, and the important transport processes in buildings. Because advection usually dominates among the transport processes, Sections 3 and 4 describe methods for predicting airflows. The concluding section summarizes the application of these models.

  3. Estimating the radon concentration in water and indoor air.

    PubMed

    Maged, A F

    2009-05-01

    The paper presents the results of radon concentration measurements in the vicinity of water, indoor air and in contact to building walls. The investigations were carried out using CR-39 track detectors. Samples of ground water flowing out of many springs mostly in Arabian Gulf area except one from Germany have been studied. The results are compared with international recommendations and the values are found to be lower than the recommended value. Measuring the mean indoor radon concentrations in air and in contact to building walls in the dwellings of Kuwait University Campus were found 24.2 +/- 7.7, and 462 +/- 422 Bq m(-3) respectively. These values lead to average effective dose equivalent rates of 1.3 +/- 0.4 and 23 +/- 21 mSv year(-1), respectively.

  4. Effect of outside air ventilation rate on VOC concentrations and emissions in a call center

    SciTech Connect

    Hodgson, A.T.; Faulkner, D.; Sullivan, D.P.; DiBartolomeo, D.L.; Russell, M.L.; Fisk, W.J.

    2002-01-01

    A study of the relationship between outside air ventilation rate and concentrations of VOCs generated indoors was conducted in a call center. Ventilation rates were manipulated in the building's four air handling units (AHUs). Concentrations of VOCs in the AHU returns were measured on 7 days during a 13-week period. Indoor minus outdoor concentrations and emission factors were calculated. The emission factor data was subjected to principal component analysis to identify groups of co-varying compounds based on source type. One vector represented emissions of solvents from cleaning products. Another vector identified occupant sources. Direct relationships between ventilation rate and concentrations were not observed for most of the abundant VOCs. This result emphasizes the importance of source control measures for limiting VOC concentrations in buildings.

  5. Variability of air ion concentrations in urban Paris

    NASA Astrophysics Data System (ADS)

    Dos Santos, V. N.; Herrmann, E.; Manninen, H. E.; Hussein, T.; Hakala, J.; Nieminen, T.; Aalto, P. P.; Merkel, M.; Wiedensohler, A.; Kulmala, M.; Petäjä, T.; Hämeri, K.

    2015-12-01

    Air ion concentrations influence new particle formation and consequently the global aerosol as potential cloud condensation nuclei. We aimed to evaluate air ion concentrations and characteristics of new particle formation events (NPF) in the megacity of Paris, France, within the MEGAPOLI (Megacities: Emissions, urban, regional and Global Atmospheric Pollution and climate effects, and Integrated tools for assessment and mitigation) project. We measured air ion number size distributions (0.8-42 nm) with an air ion spectrometer and fine particle number concentrations (> 6 nm) with a twin differential mobility particle sizer in an urban site of Paris between 26 June 2009 and 4 October 2010. Air ions were size classified as small (0.8-2 nm), intermediate (2-7 nm), and large (7-20 nm). The median concentrations of small and large ions were 670 and 680 cm-3, respectively, (sum of positive and negative polarities), whereas the median concentration of intermediate ions was only 20 cm-3, as these ions were mostly present during new particle formation bursts, i.e. when gas-to-particle conversion produced fresh aerosol particles from gas phase precursors. During peaks in traffic-related particle number, the concentrations of small and intermediate ions decreased, whereas the concentrations of large ions increased. Seasonal variations affected the ion population differently, with respect to their size and polarity. NPF was observed in 13 % of the days, being most frequent in spring and late summer (April, May, July, and August). The results also suggest that NPF was favoured on the weekends in comparison to workdays, likely due to the lower levels of condensation sinks in the mornings of weekends (CS weekdays 09:00: 18 × 10-3 s-1; CS weekend 09:00: 8 × 10-3 s-1). The median growth rates (GR) of ions during the NPF events varied between 3 and 7 nm h-1, increasing with the ion size and being higher on workdays than on weekends for intermediate and large ions. The median GR of

  6. Air concentrations of PBDEs on in-flight airplanes and assessment of flight crew inhalation exposure.

    PubMed

    Allen, Joseph G; Sumner, Ann Louise; Nishioka, Marcia G; Vallarino, Jose; Turner, Douglas J; Saltman, Hannah K; Spengler, John D

    2013-07-01

    To address the knowledge gaps regarding inhalation exposure of flight crew to polybrominated diphenyl ethers (PBDEs) on airplanes, we measured PBDE concentrations in air samples collected in the cabin air at cruising altitudes and used Bayesian Decision Analysis (BDA) to evaluate the likelihood of inhalation exposure to result in the average daily dose (ADD) of a member of the flight crew to exceed EPA Reference Doses (RfDs), accounting for all other aircraft and non-aircraft exposures. A total of 59 air samples were collected from different aircraft and analyzed for four PBDE congeners-BDE 47, 99, 100 and 209 (a subset were also analyzed for BDE 183). For congeners with a published RfD, high estimates of ADD were calculated for all non-aircraft exposure pathways and non-inhalation exposure onboard aircraft; inhalation exposure limits were then derived based on the difference between the RfD and ADDs for all other exposure pathways. The 95th percentile measured concentrations of PBDEs in aircraft air were <1% of the derived inhalation exposure limits. Likelihood probabilities of 95th percentile exposure concentrations >1% of the defined exposure limit were zero for all congeners with published RfDs.

  7. Air concentrations of PBDEs on in-flight airplanes and assessment of flight crew inhalation exposure.

    PubMed

    Allen, Joseph G; Sumner, Ann Louise; Nishioka, Marcia G; Vallarino, Jose; Turner, Douglas J; Saltman, Hannah K; Spengler, John D

    2013-07-01

    To address the knowledge gaps regarding inhalation exposure of flight crew to polybrominated diphenyl ethers (PBDEs) on airplanes, we measured PBDE concentrations in air samples collected in the cabin air at cruising altitudes and used Bayesian Decision Analysis (BDA) to evaluate the likelihood of inhalation exposure to result in the average daily dose (ADD) of a member of the flight crew to exceed EPA Reference Doses (RfDs), accounting for all other aircraft and non-aircraft exposures. A total of 59 air samples were collected from different aircraft and analyzed for four PBDE congeners-BDE 47, 99, 100 and 209 (a subset were also analyzed for BDE 183). For congeners with a published RfD, high estimates of ADD were calculated for all non-aircraft exposure pathways and non-inhalation exposure onboard aircraft; inhalation exposure limits were then derived based on the difference between the RfD and ADDs for all other exposure pathways. The 95th percentile measured concentrations of PBDEs in aircraft air were <1% of the derived inhalation exposure limits. Likelihood probabilities of 95th percentile exposure concentrations >1% of the defined exposure limit were zero for all congeners with published RfDs. PMID:22739680

  8. Lean flammability limit of downward propagating hydrogen-air flames

    NASA Technical Reports Server (NTRS)

    Patnaik, G.; Kailasanath, K.

    1992-01-01

    Detailed multidimensional numerical simulations that include the effects of wall heat losses have been performed to study the dynamics of downward flame propagation and extinguishment in lean hydrogen-air mixtures. The computational results show that a downward propagating flame in an isothermal channel has a flammability limit of around 9.75 percent. This is in excellent agreement with experimental results. Also in excellent agreement are the detailed observations of the flame behavior at the point of extinguishment. The primary conclusion of this work is that detailed numerical simulations that include wall heat losses and the effect of gravity can adequately simulate the dynamics of the extinguishment process in downward-propagating hydrogen-air flames. These simulations can be examined in detail to gain understanding of the actual extinction process.

  9. A PRINCIPAL COMPONENT ANALYSIS OF THE CLEAN AIR STATUS AND TRENDS NETWORK (CASTNET) AIR CONCENTRATION DATA

    EPA Science Inventory

    The spatial and temporal variability of ambient air concentrations of SO2, SO42-, NO3, HNO3, and NH4+ obtained from EPA's CASTNet was examined using an objective, statistically based technique...

  10. Limits of sensing temporal concentration changes by single cells.

    PubMed

    Mora, Thierry; Wingreen, Ned S

    2010-06-18

    Berg and Purcell [Biophys. J. 20, 193 (1977)] calculated how the accuracy of concentration sensing by single-celled organisms is limited by noise from the small number of counted molecules. Here we generalize their results to the sensing of concentration ramps, which is often the biologically relevant situation (e.g., during bacterial chemotaxis). We calculate lower bounds on the uncertainty of ramp sensing by three measurement devices: a single receptor, an absorbing sphere, and a monitoring sphere. We contrast two strategies, simple linear regression of the input signal versus maximum likelihood estimation, and show that the latter can be twice as accurate as the former. Finally, we consider biological implementations of these two strategies, and identify possible signatures that maximum likelihood estimation is implemented by real biological systems.

  11. Limits of Sensing Temporal Concentration Changes by Single Cells

    NASA Astrophysics Data System (ADS)

    Mora, Thierry; Wingreen, Ned S.

    2010-06-01

    Berg and Purcell [Biophys. J. 20, 193 (1977)BIOJAU0006-349510.1016/S0006-3495(77)85544-6] calculated how the accuracy of concentration sensing by single-celled organisms is limited by noise from the small number of counted molecules. Here we generalize their results to the sensing of concentration ramps, which is often the biologically relevant situation (e.g., during bacterial chemotaxis). We calculate lower bounds on the uncertainty of ramp sensing by three measurement devices: a single receptor, an absorbing sphere, and a monitoring sphere. We contrast two strategies, simple linear regression of the input signal versus maximum likelihood estimation, and show that the latter can be twice as accurate as the former. Finally, we consider biological implementations of these two strategies, and identify possible signatures that maximum likelihood estimation is implemented by real biological systems.

  12. BOREAS TGB-7 Ambient Air Herbicide and Organochlorine Concentration Data

    NASA Technical Reports Server (NTRS)

    Waite, Don; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

    2000-01-01

    The BOReal Ecosystem-Atmosphere Study Trace Gas Biogeochemistry (BOREAS TGB)-7 team measured the concentration and flux of several agricultural pesticides in air, rainwater, and dry deposition samples in order to determine the associated yearly deposition rates. This data set contains information on the ambient air concentration of seven herbicides [2,4- dichlorophenoxyacidic_acid (2,4-D), bromoxynil, dicamb, 2-methyl-4-chlorophenoxyacetic acid (MCPA), triallate, trifluralin, and diclop-methyl] known to appear in the atmosphere of the Canadian prairies. Also, the concentration of three herbicides (atrazine, alachlor, and metolachlor), two groups of insecticides (lindane and breakdown products and dichloro-diphenyl-trichloroethane (DDT) and breakdown products), and several polychlorinated biphenyls commonly used in the central United States was measured. All of these chemicals are reported, in the literature, to be transported in the atmosphere. Many have been reported to occur in boreal and arctic food chains. The sampling was carried out from 16-Jun to 13-Aug-1993 and 04-May to 20-Jul-1994 at the BOREAS site in the Prince Albert National Park (Waskesiu). The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884).

  13. Effect of backyard burning on dioxin deposition and air concentrations.

    PubMed

    Wevers, M; De Fré, R; Desmedt, M

    2004-03-01

    The influence from open burning of garden and household waste on locally measured dioxin deposition and air concentrations was evaluated in three sets of experiments: the combustion of garden waste in barrels and in open fires, and the incineration of household waste in an empty oil drum. Each set was composed of eight individual experiments over 4 h. Deposition gauges were located 20 m NE, SE, SW and NW with respect to the source and on a background location at 400 m SW. Air samples were taken in the plume with a medium volume sampler equipped with a quartz filter and a polyurethane plug. The results illustrate deposition increments in the wind direction at a distance of 20 m from the source of 0.8 pg TEQ/m2 day for garden waste and 2.5 pg TEQ/m2 day for household waste. Concentrations in the plume were increased by 160-580 fg TEQ/m3 over a period of 12 and 31 h respectively. Expressed at a reference CO2 concentration of 9% this corresponds with a range from 0.8 to 3.6 ng TEQ/m3, which is comparable with a poorly controlled MSWI. Emission factors in the order of magnitude of 4.5 ng TEQ/kg combusted garden waste and 35 ng TEQ/kg burned municipal waste were determined.

  14. Indoor air-assessment: Indoor concentrations of environmental carcinogens

    SciTech Connect

    Gold, K.W.; Naugle, D.F.; Berry, M.A.

    1991-01-01

    In the report, indoor concentration data are presented for the following general categories of air pollutants: radon-222, environmental tobacco smoke (ETS), asbestos, gas phase organic compounds, formaldehyde, polycyclic aromatic hydrocarbons (PAH), pesticides, and inorganic compounds. These pollutants are either known or suspect carcinogens (i.e., radon-222, asbestos) or more complex mixtures or classes of compounds which contain known or suspect carcinogens. Concentration data for individual carcinogenic compounds in complex mixtures are usually far from complete. The data presented for complex mixtures often include compounds which are not carcinogenic or for which data are insufficient to evaluate carcinogenicity. Their inclusion is justified, however, by the possibility that further work may show them to be carcinogens, cocarcinogens, initiators or promotors, or that they may be employed as markers (e.g., nicotine, acrolein) for the estimation of exposure to complex mixtures.

  15. Concentrations of air toxics in motor vehicle-dominated environments.

    PubMed

    Fujita, Eric M; Campbell, David E; Zielinska, Barbara; Arnott, William P; Chow, Judith C

    2011-02-01

    We at the Desert Research Institute (DRI*) measured volatile organic compounds (VOCs), including several mobile-source air toxics (MSATs), particulate matter with a mass mean aerodynamic diameter < or = 2.5 pm (PM2.5), black carbon (BC), nitrogen oxides (NOx), particulate matter (PM), and carbon monoxide (CO) on highways in Los Angeles County during summer and fall 2004, to characterize the diurnal and seasonal variations in measured concentrations related to volume and mix of traffic. Concentrations of on-road pollutants were then compared to corresponding measurements at fixed monitoring sites. The on-road concentrations of CO and MSATs were higher in the morning under stable atmospheric conditions and during periods of higher traffic volumes. In contrast, BC concentrations, measured as particulate light absorption, were higher on truck routes during the midday sampling periods despite more unstable atmospheric conditions. Compared to the measurements at the three near-road sites, the 1-hour averages of on-road BC concentrations were as much as an order of magnitude higher. The peak 1-minute average concentrations were two orders of magnitude higher for BC and were between two and six times higher for PM2.5 mass. The on-road concentrations of benzene, toluene, ethylbenzene, and xylenes (BTEX) during the summer were 3.5 +/- 0.7 and 1.2 +/- 0.6 times higher during morning and afternoon commuting periods, respectively, compared to annual average 24-hour concentrations measured at air toxic monitoring network sites. These ratios were higher during the fall, with smaller diurnal differences (4.8 +/- 0.7 and 3.9 +/- 0.6 for morning and afternoon commuting periods, respectively). Ratios similar to those for BTEX were obtained for 1,3-butadiene (BD) and styrene. On-road concentrations of formaldehyde and acetaldehyde were up to two times higher than at air toxics monitoring sites, with fall ratios slightly higher than summer ratios. Chemical mass balance (CMB) receptor

  16. Physical limits to concentration sensing in biochemical signaling

    NASA Astrophysics Data System (ADS)

    Licata, Nicholas; Setayeshgar, Sima

    2011-03-01

    In many biological systems, signals are carried by changes in the concentration of diffusable molecules which are transduced by receptors. It has been demonstrated experimentally that many signaling systems, from regulation of gene expression during development to bacterial chemotaxis, operate with remarkable sensitivity as indicated by a reliable response to small fractional changes in concentration. This sensitivity has contributions from an irreducible noise arising from the inherent random nature of the diffusing input signal, as well as from the chemical measurement process. By explicitly evaluating these theoretically derived contributions for the experimentally well- characterized bacterial chemotaxis network and motor response, we show that they are comparable to within factors of order unity, consistent with the observation that the measurement error approaches the physical lower limit set by diffusion. We extend our analysis to a class of ligand-gated ion channels, demonstrating the generality of this result where accuracy is especially important for the signaling system. This work was supported by the National Science Foundation.

  17. Thermodynamic limitations of photosynthetic water oxidation at high proton concentrations.

    PubMed

    Zaharieva, Ivelina; Wichmann, Jörg M; Dau, Holger

    2011-05-20

    In oxygenic photosynthesis, solar energy drives the oxidation of water catalyzed by a Mn(4)Ca complex bound to the proteins of Photosystem II. Four protons are released during one turnover of the water oxidation cycle (S-state cycle), implying thermodynamic limitations at low pH. For proton concentrations ranging from 1 nm (pH 9) to 1 mm (pH 3), we have characterized the low-pH limitations using a new experimental approach: a specific pH-jump protocol combined with time-resolved measurement of the delayed chlorophyll fluorescence after nanosecond flash excitation. Effective pK values were determined for low-pH inhibition of the light-induced S-state transitions: pK(1)=3.3 ± 0.3, pK(2)=3.5 ± 0.2, and pK(3)≈pK(4)=4.6 ± 0.2. Alkaline inhibition was not observed. An extension of the classical Kok model facilitated assignment of these four pK values to specific deprotonation steps in the reaction cycle. Our results provide important support to the extended S-state cycle model and criteria needed for assessment of quantum chemical calculations of the mechanism of water oxidation. They also imply that, in intact organisms, the pH in the lumen compartment can hardly drop below 5, thereby limiting the ΔpH contribution to the driving force of ATP synthesis. PMID:21464129

  18. Variation of the pressure limits of flame propagation with tube diameter for propane-air mixtures

    NASA Technical Reports Server (NTRS)

    Belles, Frank E; Simon, Dorothy M

    1951-01-01

    An investigation was made of the variation of the pressure limits of flame propagation with tube diameter for quiescent propane with tube diameter for quiescent propane-air mixtures. Pressure limits were measured in glass tubes of six different inside diameters, with a precise apparatus. Critical diameters for flame propagation were calculated and the effect of pressure was determined. The critical diameters depended on the pressure to the -0.97 power for stoichiometric mixtures. The pressure dependence decreased with decreasing propane concentration. Critical diameters were related to quenching distance, flame speeds, and minimum ignition energy.

  19. Determination of radionuclide concentrations in ground level air using the ASS-500 high volume sampler

    SciTech Connect

    Frenzel, E.; Arnold, D.; Wershofen, H.

    1996-06-01

    A method for determination of radionuclide concentrations in air aerosol samples collected by the high volume aerosol sampler ASS-500 was elaborated. The aerosol sampling station ASS-500 is a Stand alone, all-weather proofed instrument. It is designed for representative sampling of airborne radionuclides from ground level air at a height of about 1.5 m above ground level. The ASS-500 station enables continuous air monitoring both normal and emergency Situations. The collection of aerosols on the Petrianov FPP-15-1.5 type filter out of an air volume of about 100,000 m{sup 3} (sampling period 1 wk) or of about 250,000 m{sup 3} (sampling period 3 wk) admits accurate spectrometric low level measurements of natural and artificial radionuclides. The achieved detection limit is 0.5 {mu}Bq m{sup -3} and 0.2 {mu}Bq m{sup -3} for {sup 137}Cs, respectively. A new developed air flow Meter system allows to enhance the collected air volume to about 150,000 m{sup 3} per week and lowers the detection limit to <0.4 {mu}Bq m{sup -3} for {sup 137}Cs for weekly collected aerosol samples. In Poland the CLOR uses 9 Stations ASS-500 at different sites as atmospheric radioactivity control system. On the basis of spectrometric measurements of natural and artificial radionuclides in the collected aerosol samples at the different sites, CLOR establishes a weekly report about the radiological situation at Poland for responsible authorities. The very low achievable detection limit of the Station ASS-500 due 10 the high air flow fate and the long possible sampling period were the key argument for other government radiation protection authorities in Europe to introduce the Station ASS-500 into their low level radionuclide atmospheric monitoring programs (Austria, Belarus, France, Germany, Iceland, Spain, Switzerland, Ukraine).

  20. Catalytic wet air oxidation of high concentration pharmaceutical wastewater.

    PubMed

    Zhan, Wei; Wang, Xiaocong; Li, Daosheng; Ren, Yongzheng; Liu, Dongqi; Kang, Jianxiong

    2013-01-01

    In this study, we investigated the pretreatment of a high concentration pharmaceutical wastewater by catalytic wet air oxidation (CWAO) process. Different experiments were conducted to investigate the effects of the catalyst type, operating temperature, initial system pH, and oxygen partial pressure on the oxidation of the wastewater. Results show that the catalysts prepared by the co-precipitation method have better catalytic activity compared to others. Chemical oxygen demand (COD) conversion increased with the increase in temperature from 160 to 220 °C and decreased with the increase in pH. Moreover, the effect of the oxygen partial pressure on the COD conversion was significant only during the first 20 min of the reaction. Furthermore, the biodegradability of the wastewater improved greatly after CWAO, the ratio of BOD5/COD increased less than 0.1-0.75 when treated at 220 °C (BOD: biochemical oxygen demand). PMID:23676399

  1. Catalytic wet air oxidation of high concentration pharmaceutical wastewater.

    PubMed

    Zhan, Wei; Wang, Xiaocong; Li, Daosheng; Ren, Yongzheng; Liu, Dongqi; Kang, Jianxiong

    2013-01-01

    In this study, we investigated the pretreatment of a high concentration pharmaceutical wastewater by catalytic wet air oxidation (CWAO) process. Different experiments were conducted to investigate the effects of the catalyst type, operating temperature, initial system pH, and oxygen partial pressure on the oxidation of the wastewater. Results show that the catalysts prepared by the co-precipitation method have better catalytic activity compared to others. Chemical oxygen demand (COD) conversion increased with the increase in temperature from 160 to 220 °C and decreased with the increase in pH. Moreover, the effect of the oxygen partial pressure on the COD conversion was significant only during the first 20 min of the reaction. Furthermore, the biodegradability of the wastewater improved greatly after CWAO, the ratio of BOD5/COD increased less than 0.1-0.75 when treated at 220 °C (BOD: biochemical oxygen demand).

  2. 46 CFR Appendix A to Part 197 - Air No-Decompression Limits

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Air No-Decompression Limits A Appendix A to Part 197... STANDARDS GENERAL PROVISIONS Pt. 197, App. A Appendix A to Part 197—Air No-Decompression Limits The following table gives the depth versus bottom time limits for single, no-decompression, air dives...

  3. 46 CFR Appendix A to Part 197 - Air No-Decompression Limits

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Air No-Decompression Limits A Appendix A to Part 197... STANDARDS GENERAL PROVISIONS Pt. 197, App. A Appendix A to Part 197—Air No-Decompression Limits The following table gives the depth versus bottom time limits for single, no-decompression, air dives...

  4. 46 CFR Appendix A to Part 197 - Air No-Decompression Limits

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Air No-Decompression Limits A Appendix A to Part 197... STANDARDS GENERAL PROVISIONS Pt. 197, App. A Appendix A to Part 197—Air No-Decompression Limits The following table gives the depth versus bottom time limits for single, no-decompression, air dives...

  5. BTEX in indoor air of waterpipe cafés: Levels and factors influencing their concentrations.

    PubMed

    Hazrati, Sadegh; Rostami, Roohollah; Fazlzadeh, Mehdi

    2015-08-15

    BTEX (benzene, toluene, ethylbenzene and xylene) concentrations, factors affecting their levels, and the exposure risks related to these compounds were studied in waterpipe (Ghalyun/Hookah) cafés of Ardabil city in Islamic Republic of Iran. 81 waterpipe cafés from different districts of Ardabil city were selected and their ambient air was monitored for BTEX compounds. Air samples were taken from standing breathing zone of employees, ~150 cm above the ground level, and were analyzed using GC-FID. In each case, the types of smoked tobacco (regular, fruit flavored), types of ventilation systems (natural/artificial), and the floor level at which the café was located were investigated. A high mean concentration of 4.96±2.63 mg/m(3) corresponding to long term exposure to benzene-related cancer risk of 4314×10(-6) was estimated. The levels of the remaining compounds were lower than the national guideline limits, but their hazard quotients (HQ) for long term exposure to ethylbenzene (1.15) and xylene (17.32) exceeded the HQ unit value. Total hazard indices (HI) of 63.23 were obtained for non-cancer risks. Type of the smoked tobacco was the most important factor influencing BTEX concentrations in the cafés. BTEX concentrations in indoor ambient air of Ardabil waterpipe cafés were noticeably high, and therefore may pose important risks for human health on both short and long term exposures. PMID:25912530

  6. Use of dust fall filters as passive samplers for metal concentrations in air for communities near contaminated mine tailings

    PubMed Central

    Beamer, P.I.; Sugeng, A. J.; Kelly, M.D.; Lothrop, N.; Klimecki, W.; Wilkinson, S.T.; Loh, M.

    2014-01-01

    Mine tailings are a source of metal exposures in many rural communities. Multiple air samples are necessary to assess the extent of exposures and factors contributing to these exposures. However, air sampling equipment is costly and requires trained personnel to obtain measurements, limiting the number of samples that can be collected. Simple, low-cost methods are needed to allow for increased sample collection. The objective of our study was to assess if dust fall filters can serve as passive air samplers and be used to characterize potential exposures in a community near contaminated mine tailings. We placed filters in cylinders, concurrently with active indoor air samplers, in 10 occupied homes. We calculated an estimated flow rate by dividing the mass on each dust fall filter by the bulk air concentration and the sampling duration. The mean estimated flow rate for dust fall filters was significantly different during sampling periods with precipitation. The estimated flow rate was used to estimate metal concentration in the air of these homes, as well as in 31 additional homes in another rural community impacted by contaminated mine tailings. The estimated air concentrations had a significant linear association with the measured air concentrations for beryllium, manganese and arsenic (p<0.05), whose primary source in indoor air is resuspended soil from outdoors. In the second rural community, our estimated metal concentrations in air were comparable to active air sampling measurements taken previously. This passive air sampler is a simple low-cost method to assess potential exposures near contaminated mining sites. PMID:24469149

  7. IMPACT OF AN OZONE GENERATOR AIR CLEANER ON STYRENE CONCENTRATIONS IN AN INDOOR AIR QUALITY RESEARCH CHAMBER

    EPA Science Inventory

    The paper gives results of an investigation of the impact of an ozone generator air cleaner on vapor-phase styrene concentrations in a full-scale indoor air quality test chamber. The time history of the concentrations of styrene and ozone is well predicted by a simulation model u...

  8. 40 CFR 60.2250 - What are the emission limitations for air curtain incinerators?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... air curtain incinerators? 60.2250 Section 60.2250 Protection of Environment ENVIRONMENTAL PROTECTION... 1, 2001 Air Curtain Incinerators § 60.2250 What are the emission limitations for air curtain incinerators? (a) Within 60 days after your air curtain incinerator reaches the charge rate at which it...

  9. 40 CFR 60.2250 - What are the emission limitations for air curtain incinerators?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... air curtain incinerators? 60.2250 Section 60.2250 Protection of Environment ENVIRONMENTAL PROTECTION... 1, 2001 Air Curtain Incinerators § 60.2250 What are the emission limitations for air curtain incinerators? (a) Within 60 days after your air curtain incinerator reaches the charge rate at which it...

  10. 40 CFR 60.2250 - What are the emission limitations for air curtain incinerators?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... air curtain incinerators? 60.2250 Section 60.2250 Protection of Environment ENVIRONMENTAL PROTECTION... 1, 2001 Air Curtain Incinerators § 60.2250 What are the emission limitations for air curtain incinerators? (a) Within 60 days after your air curtain incinerator reaches the charge rate at which it...

  11. 10 CFR 835.209 - Concentrations of radioactive material in air.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Concentrations of radioactive material in air. 835.209... External Exposure § 835.209 Concentrations of radioactive material in air. (a) The derived air... exposures to airborne radioactive material. (b) The estimation of internal dose shall be based on...

  12. Rich methane/air flames: Burning velocities, extinction limits, and flammability limit

    SciTech Connect

    Bui-Pham, M.N.; Miller, J.A.

    1994-12-31

    A theoretical investigation has been conducted to establish a reliable chemical kinetic mechanism that can determine the extinction limit of opposed-flow, strained, rich premixed methane-air flames. In the process of developing this kinetic representation for rich methane-air flames, we found that the heat of formation of {sup 1}CH{sub 2}=102.5 kcal/mole, which is 1 kcal/mole higher than the currently available thermochemical data, gives the best agreement with experimental data on burning velocities for equivalence ratios between 0.5 and 1.7. Employing this value for {Delta}H{sub f{sup 1}CH{sub 2}} in our calculations, the extinction stretch rate, K{sub ex}, was found to be K{sub ex}=2250 sec {sup {minus}1} for {phi}=1.0, K{sub ex}=2000 sec{sup {minus}1} for {phi}=1.1, and K{sub ex}=1400 sec{sup {minus}1} for {phi}=1.2. These results agree better with experiments than those using a lower heat of formation of singlet methylene. In comparison with previous calculations made by Kee et al., our predictions are basically the same except that our extinction stretch rate is slightly higher at {phi}=1.0 and that our location of the maximum extinction stretch rate is closer to that found in experiments. In addition, we establish the rich flammability limit using two different criteria to be approximately between {phi}=1.61 and {phi}=1.68, which agrees very well with an experimental value of {phi}=1.67.

  13. Groundwater level and nitrate concentration trends on Mountain Home Air Force Base, southwestern Idaho

    USGS Publications Warehouse

    Williams, Marshall L.

    2014-01-01

    Mountain Home Air Force Base in southwestern Idaho draws most of its drinking water from the regional aquifer. The base is located within the State of Idaho's Mountain Home Groundwater Management Area and is adjacent to the State's Cinder Cone Butte Critical Groundwater Area. Both areas were established by the Idaho Department of Water Resources in the early 1980s because of declining water levels in the regional aquifer. The base also is listed by the Idaho Department of Environmental Quality as a nitrate priority area. The U.S. Geological Survey, in cooperation with the U.S. Air Force, began monitoring wells on the base in 1985, and currently monitors 25 wells for water levels and 17 wells for water quality, primarily nutrients. This report provides a summary of water-level and nitrate concentration data collected primarily between 2001 and 2013 and examines trends in those data. A Regional Kendall Test was run to combine results from all wells to determine an overall regional trend in water level. Groundwater levels declined at an average rate of about 1.08 feet per year. Nitrate concentration trends show that 3 wells (18 percent) are increasing in nitrate concentration trend, 3 wells (18 percent) show a decreasing nitrate concentration trend, and 11 wells (64 percent) show no nitrate concentration trend. Six wells (35 percent) currently exceed the U.S. Environmental Protection Agency's maximum contaminant limit of 10 milligrams per liter for nitrate (nitrite plus nitrate, measured as nitrogen).

  14. Nitrogen potential recovery and concentration of ammonia from swine manure using electrodialysis coupled with air stripping.

    PubMed

    Ippersiel, D; Mondor, M; Lamarche, F; Tremblay, F; Dubreuil, J; Masse, L

    2012-03-01

    The practice of intensive animal production in certain areas has resulted in excessive manure production for the available regional land base. Consequently, there is a need to develop treatment technologies to recover the valuable nutrients that manure contains so that the resulting product can be transported and used as fertilizer on agricultural land. The project presented here used electrodialysis in a dilution/concentration configuration to transfer the manure ammonia in the diluate solution by electromigration to an adjacent solution separated by an ion-exchange membrane under the driving force of an electrical potential. Then, air stripping from the electrodialysis-obtained concentrate solution without pH modification was used to isolate the ammonia in an acidic solution. An optimal process operating voltage of 17.5 V was first determined on the basis of current efficiency and total energy consumption. During the process, the swine manure pH varied from 8.5 to 8.2, values favourable for NH(4)(+) electromigration. Total ammonia nitrogen reached 21,352 mg/L in the concentrate solution, representing approximately seven times the concentration in the swine manure. Further increases in concentration were limited by water transfer from the diluate solution due to electroosmosis and osmosis. Applying vacuum to the concentrate reservoir was found to be more efficient than direct concentrate solution aeration for NH(3) recuperation in the acid trap, given that the ammonia recuperated under vacuum represented 14.5% of the theoretical value of the NH(3) present in the concentrate solution as compared to 6.2% for aeration. However, an excessively low concentrate solution pH (8.6-8.3) limited NH(3)volatilization toward the acid trap. These results suggest that the concentrate solution pH needs to be raised to promote the volatile NH(3) form of total ammonia nitrogen.

  15. Contribution of ship emissions to the concentration and deposition of air pollutants in Europe

    NASA Astrophysics Data System (ADS)

    Aksoyoglu, S.; Prévôt, A. S. H.; Baltensperger, U.

    2015-11-01

    Emissions from the marine transport sector are one of the least regulated anthropogenic emission sources and contribute significantly to air pollution. Although strict limits were introduced recently for the maximum sulfur content in marine fuels in the SECAs (sulfur emission control areas) and in the EU ports, sulfur emissions outside the SECAs and emissions of other components in all European maritime areas have continued to increase in the last two decades. We have used the air quality model CAMx with and without ship emissions for the year 2006 to determine the effects of international shipping on the annual as well as seasonal concentrations of ozone, primary and secondary components of PM2.5 and the dry and wet deposition of nitrogen and sulfur compounds in Europe. Our results suggest that emissions from international shipping affect the air quality in northern and southern Europe differently and their contributions to the air concentrations vary seasonally. The largest changes in pollutant concentrations due to ship emissions were predicted for summer. Increased concentrations of the primary particle mass were found only along the shipping routes whereas concentrations of the secondary pollutants were affected over a larger area. Concentrations of particulate sulfate increased due to ship emissions in the Mediterranean (up to 60 %), in the English Channel and the North Sea (30-35 %) while increases in particulate nitrate levels were found especially in the north, around the Benelux area (20 %) where there were high NH3 land-based emissions. Our model results showed that not only the atmospheric concentrations of pollutants are affected by ship emissions, but also depositions of nitrogen and sulfur compounds increase significantly along the shipping routes. NOx emissions from the ships especially in the English Channel and the North Sea, cause a decrease in the dry deposition of reduced nitrogen at source regions by moving it from the gas-phase to the

  16. Concentration and risk assessment of phthalates present in indoor air from newly decorated apartments

    NASA Astrophysics Data System (ADS)

    Pei, X. Q.; Song, M.; Guo, M.; Mo, F. F.; Shen, X. Y.

    2013-04-01

    Phthalate esters (PAEs) are ubiquitous in the indoor environment, owing to their use in consumer products. People spend a considerable amount of time indoors. As a result, human exposure to indoor contaminants is of great concern. People are exposed to phthalates through inhalation and dermal absorption of indoor air. In this study, the concentrations, characteristics and carcinogenic risks of gas-phase and particle-phase phthalates in indoor air from bedroom, living room and study room of 10 newly decorated apartments in Hangzhou, China were first investigated. The mean concentration of phthalates (gas-phase and particle-phase) present in household air was 12 096.4 ng m-3, of which diethyl phthalate (DEP), butylbenzyl phthalate (BBP) and di(2-ethylhexyl) phthalate (DEHP) were the most abundant compounds with concentrations of 2290 ng m-3, 3975 ng m-3 and 2437 ng m-3, respectively, totally accounting for 72.0% of ∑6PAEs. Contamination levels of phthalates varied in different compartments. The concentration of phthalates was the highest 17 363.7 ng m-3 in living room, followed with 11 389.5 ng m-3 in study room, and the lowest 9739.1 ng m-3 in bedroom. It was also found that phthalates mainly accumulated in gaseous form in household air. DEHP posed the greatest health risk to children aged 1-2. Carcinogenic risk of DEHP was evaluated to be 3.912 × 10-5, and was 39 times higher than the limit set by the U.S. EPA.

  17. 46 CFR Appendix A to Part 197 - Air No-Decompression Limits

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Air No-Decompression Limits A Appendix A to Part 197... STANDARDS GENERAL PROVISIONS Pt. 197, App. A Appendix A to Part 197—Air No-Decompression Limits The... within any 12-hour period. The limit is the maximum bottom time in minutes that a diver can spend at...

  18. Identifying an indoor air exposure limit for formaldehyde considering both irritation and cancer hazards

    PubMed Central

    Golden, Robert

    2011-01-01

    Formaldehyde is a well-studied chemical and effects from inhalation exposures have been extensively characterized in numerous controlled studies with human volunteers, including asthmatics and other sensitive individuals, which provide a rich database on exposure concentrations that can reliably produce the symptoms of sensory irritation. Although individuals can differ in their sensitivity to odor and eye irritation, the majority of authoritative reviews of the formaldehyde literature have concluded that an air concentration of 0.3 ppm will provide protection from eye irritation for virtually everyone. A weight of evidence-based formaldehyde exposure limit of 0.1 ppm (100 ppb) is recommended as an indoor air level for all individuals for odor detection and sensory irritation. It has recently been suggested by the International Agency for Research on Cancer (IARC), the National Toxicology Program (NTP), and the US Environmental Protection Agency (US EPA) that formaldehyde is causally associated with nasopharyngeal cancer (NPC) and leukemia. This has led US EPA to conclude that irritation is not the most sensitive toxic endpoint and that carcinogenicity should dictate how to establish exposure limits for formaldehyde. In this review, a number of lines of reasoning and substantial scientific evidence are described and discussed, which leads to a conclusion that neither point of contact nor systemic effects of any type, including NPC or leukemia, are causally associated with exposure to formaldehyde. This conclusion supports the view that the equivocal epidemiology studies that suggest otherwise are almost certainly flawed by identified or yet to be unidentified confounding variables. Thus, this assessment concludes that a formaldehyde indoor air limit of 0.1 ppm should protect even particularly susceptible individuals from both irritation effects and any potential cancer hazard. PMID:21635194

  19. Benzo(a)pyrene in Europe: Ambient air concentrations, population exposure and health effects.

    PubMed

    Guerreiro, C B B; Horálek, J; de Leeuw, F; Couvidat, F

    2016-07-01

    This study estimated current benzo(a)pyrene (BaP) concentration levels, population exposure and potential health impacts of exposure to ambient air BaP in Europe. These estimates were done by combining the best available information from observations and chemical transport models through the use of spatial interpolation methods. Results show large exceedances of the European target value for BaP in 2012 over large areas, particularly in central-eastern Europe. Results also show large uncertainties in the concentration estimates in regions with a few or no measurement stations. The estimation of the population exposure to BaP concentrations and its health impacts was limited to 60% of the European population, covering only the modelled areas which met the data quality requirement for modelling of BaP concentrations set by the European directive 2004/107/EC. The population exposure estimate shows that 20% of the European population is exposed to BaP background ambient concentrations above the EU target value and only 7% live in areas with concentrations under the estimated acceptable risk level of 0.12 ng m(-3). This exposure leads to an estimated 370 lung cancer incidences per year, for the 60% of the European population included in the estimation. Emissions of BaP have increased in the last decade with the increase in emissions from household combustion of biomass. At the same time, climate mitigation policies are promoting the use of biomass burning for domestic heating. The current study shows that there is a need for more BaP measurements in areas of low measurement density, particularly where high concentrations are expected, e.g. in Romania, Bulgaria, and other Balkan states. Furthermore, this study shows that the health risk posed by PAH exposure calls for better coordination between air quality and climate mitigation policies in Europe.

  20. Atmospheric light air ion concentrations and related meteorologic factors in Rezekne city, Latvia.

    PubMed

    Skromulis, Andris; Noviks, Gotfrids

    2012-04-01

    The well-minded impact of light negative air ions on human organism is still under discussion. The measurements of air ions are not widespread in Latvia yet. The paper presents new results of air pollution evaluation in Rezekne city. Measurements of positive and negative air ion concentrations in Rezekne city were taken during the spring, summer and autumn 2009 and during the winter 2010. Measurements were taken by portative air ions counter "Sapfir-3M" in eight different points of Rezekne city thrice a day. The concentrations of positive and negative air ions with mobility factor k > or = 0.4 cm2 V(-1) s(-1) were measured. Temperature, relative humidity, wind velocity, direction, etc., were also taken into account. The approximate interconnection between ionization and chemical and mechanical air pollution in relation with meteorological conditions was analyzed. The highest level of air ion concentration was observed in mornings, whereas in afternoons this concentration level decreased due to the growth of anthropogenic air pollution in the city, as light air ions, because of their charge, promoted the coagulation and the settlement of pollution particles. This regularity is typical for summer, whereas in spring, autumn and winter it is not characteristic. The unipolarity factor was usually less than 1 in mornings, but usually larger than 1 in afternoons especially in the most polluted city areas where minor concentration of air ions was detected. The ionization level is an original indicator of energetic saturation and aerosol pollution of atmospheric air.

  1. 40 CFR 60.2860 - What are the emission limitations for air curtain incinerators?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... air curtain incinerators? 60.2860 Section 60.2860 Protection of Environment ENVIRONMENTAL PROTECTION... Construction On or Before November 30, 1999 Model Rule-Air Curtain Incinerators § 60.2860 What are the emission limitations for air curtain incinerators? (a) After the date the initial stack test is required or...

  2. 40 CFR 60.2860 - What are the emission limitations for air curtain incinerators?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... air curtain incinerators? 60.2860 Section 60.2860 Protection of Environment ENVIRONMENTAL PROTECTION... Construction On or Before November 30, 1999 Model Rule-Air Curtain Incinerators § 60.2860 What are the emission limitations for air curtain incinerators? (a) After the date the initial stack test is required or...

  3. 40 CFR 60.2860 - What are the emission limitations for air curtain incinerators?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... air curtain incinerators? 60.2860 Section 60.2860 Protection of Environment ENVIRONMENTAL PROTECTION... Curtain Incinerators § 60.2860 What are the emission limitations for air curtain incinerators? (a) After... for air curtain incinerators? After the date the initial stack test is required or...

  4. 40 CFR 60.2250 - What are the emission limitations for air curtain incinerators?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... air curtain incinerators? 60.2250 Section 60.2250 Protection of Environment ENVIRONMENTAL PROTECTION... of Performance for Commercial and Industrial Solid Waste Incineration Units Air Curtain Incinerators § 60.2250 What are the emission limitations for air curtain incinerators? Within 60 days after your...

  5. 40 CFR 60.2250 - What are the emission limitations for air curtain incinerators?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... air curtain incinerators? 60.2250 Section 60.2250 Protection of Environment ENVIRONMENTAL PROTECTION... of Performance for Commercial and Industrial Solid Waste Incineration Units Air Curtain Incinerators § 60.2250 What are the emission limitations for air curtain incinerators? Within 60 days after your...

  6. Modeling Airborne Beryllium Concentrations From Open Air Dynamic Testing

    NASA Astrophysics Data System (ADS)

    Becker, N. M.

    2003-12-01

    A heightened awareness of airborne beryllium contamination from industrial activities was reestablished during the late 1980's and early 1990's when it became recognized that Chronic Beryllium Disease (CBD) had not been eradicated, and that the Occupational Health and Safety Administration standards for occupational air exposure to beryllium may not be sufficiently protective. This was in response to the observed CBD increase in multiple industrial settings where beryllium was manufactured and/or machined, thus producing beryllium particulates which are then available for redistribution by airborne transport. Sampling and modeling design activities were expanded at Los Alamos National Laboratory in New Mexico to evaluate potential airborne beryllium exposure to workers who might be exposed during dynamic testing activities associated with nuclear weapons Stockpile Stewardship. Herein is presented the results of multiple types of collected air measurements that were designed to characterize the production and dispersion of beryllium used in components whose performance is evaluated during high explosive detonation at open air firing sites. Data from fallout, high volume air, medium volume air, adhesive film, particle size impactor, and fine-particulate counting techniques will be presented, integrated, and applied in dispersion modeling to assess potential onsite and offsite personal exposures resulting from dynamic testing activities involving beryllium.

  7. Global Ammonia Concentrations Seen by the 13-years AIRS Measurements

    NASA Astrophysics Data System (ADS)

    Warner, Juying; Wei, Zigang; Larrabee Strow, L.; Dickerson, Russell; Nowak, John; Wang, Yuxuan

    2016-04-01

    Ammonia is an integral part of the nitrogen cycle and is projected to be the largest single contributor to each of acidification, eutrophication and secondary particulate matter in Europe by 2020 (Sutton et al., 2008). The impacts of NH3 also include: aerosol production affecting global radiative forcing, increases in emissions of the greenhouse gases nitrous oxide (N2O) and methane (CH4), and modification of the transport and deposition patterns of SO2 and NOx. Therefore, monitoring NH3 global distribution of sources is vitally important to human health with respect to both air and water quality and climate change. We have developed new daily and global ammonia (NH3) products from AIRS hyperspectral measurements. These products add value to AIRS's existing products that have made significant contributions to weather forecasts, climate studies, and air quality monitoring. With longer than 13 years of data records, these measurements have been used not only for daily monitoring purposes but also for inter-annual variability and short-term trend studies. We will discuss the global NH3 emission sources from biogenic and anthropogenic activities over many emission regions captured by AIRS. We will focus their variability in the last 13 years.

  8. LARGE-SCALE PREDICTIONS OF MOBILE SOURCE CONTRIBUTIONS TO CONCENTRATIONS OF TOXIC AIR POLLUTANTS

    EPA Science Inventory

    This presentation shows concentrations and deposition of toxic air pollutants predicted by a 3-D air quality model, the Community Multi Scale Air Quality (CMAQ) modeling system. Contributions from both on-road and non-road mobile sources are analyzed.

  9. Expiratory flow limitation in compressed air divers and oxygen divers.

    PubMed

    Tetzlaff, K; Friege, L; Reuter, M; Haber, J; Mutzbauer, T; Neubauer, B

    1998-10-01

    Divers are exposed to dense gases under hyperbaric and hyperoxic conditions and, therefore, may be at risk of developing respiratory disease. Long-term effects on respiratory function have been found in commercial divers who perform deep dives. This study was conducted to detect possible lung function changes in scuba divers who dive in shallow water using compressed air or oxygen as a breathing gas. A cross-sectional sample of 180 healthy male divers (152 air divers and 28 oxygen divers) and 34 healthy male controls underwent a diving medical examination including body plethysmography, diffusion capacity measurement and a cold-air isocapnic hyperventilation test (CAIH). Air divers and oxygen divers had a lower mid-expiratory flow at 25% of vital capacity (MEF25) than controls (p<0.01 and p<0.05, respectively). Oxygen divers also had a decreased mid-expiratory flow at 50% of vital capacity (MEF50) (p<0.05). Divers' groups and controls did not differ with respect to age, smoking or medical history. The prevalence of airway hyperresponsiveness to CAIH was 1.4% (n=3 divers). MEF25 and MEF50 were inversely related to years of diving (p<0.01 and p<0.001, respectively). The pattern of lung function changes obtained in scuba divers is consistent with small airways dysfunction and the association between diving exposure and lung function changes may indicate long-term effects on respiratory function.

  10. 32 CFR 644.415 - Army military and Air Force lands-$50,000 limitation.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 4 2011-07-01 2011-07-01 false Army military and Air Force lands-$50,000 limitation. 644.415 Section 644.415 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY... Interests § 644.415 Army military and Air Force lands—$50,000 limitation. (a) 10 U.S.C. 2672 authorizes...

  11. 32 CFR 644.415 - Army military and Air Force lands-$50,000 limitation.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 4 2010-07-01 2010-07-01 true Army military and Air Force lands-$50,000 limitation. 644.415 Section 644.415 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY... Interests § 644.415 Army military and Air Force lands—$50,000 limitation. (a) 10 U.S.C. 2672 authorizes...

  12. 32 CFR 644.415 - Army military and Air Force lands-$50,000 limitation.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 4 2013-07-01 2013-07-01 false Army military and Air Force lands-$50,000 limitation. 644.415 Section 644.415 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY... Interests § 644.415 Army military and Air Force lands—$50,000 limitation. (a) 10 U.S.C. 2672 authorizes...

  13. 32 CFR 644.415 - Army military and Air Force lands-$50,000 limitation.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 4 2014-07-01 2013-07-01 true Army military and Air Force lands-$50,000 limitation. 644.415 Section 644.415 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY... Interests § 644.415 Army military and Air Force lands—$50,000 limitation. (a) 10 U.S.C. 2672 authorizes...

  14. 32 CFR 644.415 - Army military and Air Force lands-$50,000 limitation.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 4 2012-07-01 2011-07-01 true Army military and Air Force lands-$50,000 limitation. 644.415 Section 644.415 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY... Interests § 644.415 Army military and Air Force lands—$50,000 limitation. (a) 10 U.S.C. 2672 authorizes...

  15. 40 CFR 60.2860 - What are the emission limitations for air curtain incinerators?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 7 2013-07-01 2013-07-01 false What are the emission limitations for air curtain incinerators? 60.2860 Section 60.2860 Protection of Environment ENVIRONMENTAL PROTECTION... Curtain Incinerators § 60.2860 What are the emission limitations for air curtain incinerators? After...

  16. 40 CFR 60.2860 - What are the emission limitations for air curtain incinerators?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 7 2014-07-01 2014-07-01 false What are the emission limitations for air curtain incinerators? 60.2860 Section 60.2860 Protection of Environment ENVIRONMENTAL PROTECTION... Curtain Incinerators § 60.2860 What are the emission limitations for air curtain incinerators? After...

  17. Effect of an ozone-generating air-purifying device on reducing concentrations of formaldehyde in air

    SciTech Connect

    Esswein, E.J.; Boeniger, M.F.

    1994-02-01

    Formaldehyde, an air contaminant found in many indoor air investigations, poses distinct occupational exposure hazards in certain job categories (e.g., mortuary science) but is also of concern when found or suspected in office buildings and homes. A variety of air-purifying devices (APDs) are currently available or marketed for application to reduce or remove concentrations of a variety of indoor air pollutants through the use of ozone as a chemical oxidant. An investigation was conducted to determine if concentrations of formaldehyde similar to those found in industrial hygiene evaluations of funeral homes could be reduced with the use of an ozone-generating APD. An ozone-generating APD was placed in an exposure chamber and formaldehyde-containing embalming solution was allowed to evaporate naturally, creating peak and mean chamber concentrations of 2.5 and 1.3 ppm, respectively. Continuous-reading instruments were used to sample for formaldehyde and ozone. Active sampling methods were also used to sample simultaneously for formaldehyde and a possible reactant product, formic acid. Triplicate measurements were made in each of three evaluations: formaldehyde alone, ozone alone, and formaldehyde and ozone combined. Concentrations of formaldehyde were virtually identical with and without 0.5 ppm ozone. No reduction in formaldehyde concentration was found during a 90-minute evaluation using ozone at this concentration with peak and average concentrations of approximately 2.5 and 1.3 ppm formaldehyde, respectively. The results of this investigation suggest that the use of ozone is ineffective in reducing concentrations of formaldehyde. Because ozone has demonstrated health hazards, and is a regulated air contaminant in both the occupational and ambient environment, the use of ozone as an air purification agent in indoor air does not seem warranted. 25 refs., 5 figs., 4 tabs.

  18. Reduced-Rank Spatio-Temporal Modeling of Air Pollution Concentrations in the Multi-Ethnic Study of Atherosclerosis and Air Pollution1

    PubMed Central

    Olives, Casey; Sheppard, Lianne; Lindström, Johan; Sampson, Paul D.; Kaufman, Joel D.; Szpiro, Adam A.

    2016-01-01

    There is growing evidence in the epidemiologic literature of the relationship between air pollution and adverse health outcomes. Prediction of individual air pollution exposure in the Environmental Protection Agency (EPA) funded Multi-Ethnic Study of Atheroscelerosis and Air Pollution (MESA Air) study relies on a flexible spatio-temporal prediction model that integrates land-use regression with kriging to account for spatial dependence in pollutant concentrations. Temporal variability is captured using temporal trends estimated via modified singular value decomposition and temporally varying spatial residuals. This model utilizes monitoring data from existing regulatory networks and supplementary MESA Air monitoring data to predict concentrations for individual cohort members. In general, spatio-temporal models are limited in their efficacy for large data sets due to computational intractability. We develop reduced-rank versions of the MESA Air spatio-temporal model. To do so, we apply low-rank kriging to account for spatial variation in the mean process and discuss the limitations of this approach. As an alternative, we represent spatial variation using thin plate regression splines. We compare the performance of the outlined models using EPA and MESA Air monitoring data for predicting concentrations of oxides of nitrogen (NOx)—a pollutant of primary interest in MESA Air—in the Los Angeles metropolitan area via cross-validated R2. Our findings suggest that use of reduced-rank models can improve computational efficiency in certain cases. Low-rank kriging and thin plate regression splines were competitive across the formulations considered, although TPRS appeared to be more robust in some settings. PMID:27014398

  19. Time variations of 222Rn concentration and air exchange rates in a Hungarian cave.

    PubMed

    Nagy, Hedvig Éva; Szabó, Zsuzsanna; Jordán, Gyozo; Szabó, Csaba; Horváth, Akos; Kiss, Attila

    2012-09-01

    A long-term radon concentration monitoring was carried out in the Pál-völgy cave, Budapest, Hungary, for 1.5 years. Our major goal was to determine the time dependence of the radon concentration in the cave to characterise the air exchange and define the most important environmental parameters that influence the radon concentration inside the cave. The radon concentration in the cave air was measured continuously by an AlphaGuard radon monitor, and meteorological parameters outside the cave were collected simultaneously. The air's radon concentration in the cave varied between 104 and 7776 Bq m(-3), the annual average value was 1884±85 Bq m(-3). The summer to winter radon concentration ratio was as high as 21.8. The outside air temperature showed the strongest correlation with the radon concentration in the cave, the correlation coefficient (R) was 0.76. PMID:22462600

  20. 40 CFR 227.27 - Limiting permissible con-cen-tra-tion (LPC).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Limiting permissible con-cen-tra-tion (LPC). 227.27 Section 227.27 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Definitions § 227.27 Limiting permissible con-cen-tra-tion (LPC). (a) The limiting permissible...

  1. Setting limits: Using air pollution thresholds to protect and restore U.S. ecosystems

    USGS Publications Warehouse

    Fenn, M.E.; Lambert, K.F.; Blett, T.F.; Burns, Douglas A.; Pardo, L.H.; Lovett, Gary M.; Haeuber, R. A.; Evers, D.C.; Driscoll, C.T.; Jeffries, D.S.

    2011-01-01

    More than four decades of research provide unequivocal evidence that sulfur, nitrogen, and mercury pollution have altered, and will continue to alter, our nation's lands and waters. The emission and deposition of air pollutants harm native plants and animals, degrade water quality, affect forest productivity, and are damaging to human health. Many air quality policies limit emissions at the source but these control measures do not always consider ecosystem impacts. Air pollution thresholds at which ecological effects are observed, such as critical loads, are effective tools for assessing the impacts of air pollution on essential ecosystem services and for informing public policy. U.S. ecosystems can be more effectively protected and restored by using a combination of emissions-based approaches and science-based thresholds of ecosystem damage. Based on the results of a comprehensive review of air pollution thresholds, we conclude: ??? Ecosystem services such as air and water purification, decomposition and detoxification of waste materials, climate regulation, regeneration of soil fertility, production and biodiversity maintenance, as well as crop, timber and fish supplies are impacted by deposition of nitrogen, sulfur, mercury and other pollutants. The consequences of these changes may be difficult or impossible to reverse as impacts cascade throughout affected ecosystems. ??? The effects of too much nitrogen are common across the U.S. and include altered plant and lichen communities, enhanced growth of invasive species, eutrophication and acidification of lands and waters, and habitat deterioration for native species, including endangered species. ??? Lake, stream and soil acidification is widespread across the eastern United States. Up to 65% of lakes within sensitive areas receive acid deposition that exceeds critical loads. ??? Mercury contamination adversely affects fish in many inland and coastal waters. Fish consumption advisories for mercury exist in all 50

  2. The concentrations of culturable microorganisms in relation to particulate matter in urban air

    NASA Astrophysics Data System (ADS)

    Haas, D.; Galler, H.; Luxner, J.; Zarfel, G.; Buzina, W.; Friedl, H.; Marth, E.; Habib, J.; Reinthaler, F. F.

    2013-02-01

    The ambient air consists not only of gases but also of bioaerosols and particulate matter. The concentrations of particulate matter in relation to the culturable microorganisms in the urban ambient air and their dependence on air temperature and relative humidity were investigated. The seasonal distribution of particles sizes, the concentrations of aerobic mesophilic bacteria and xerophilic fungi in the air were evaluated. Moreover, the identification of the fungal genera Cladosporium, Aspergillus and Penicillium were conducted. Within one year at 177 days particle and microorganism concentrations in the ambient air were recorded in the city centre of Graz/Austria. The results show that the concentrations of fine particles and coarse particles were the highest in winter and decreased continuously to a minimum in the summer months depending on temperature and air humidity. The concentrations of xerophilic fungi showed no correlation to the different particle concentrations. The spore concentrations of Cladosporium spp. showed the same results of xerophilic fungi whereas the genera Penicillium and Aspergillus increased with the increase of fine particles. The concentrations of mesophilic bacteria were positively correlated with all particle counts. The maximum mesophilic bacteria concentrations were found in the winter months. Further studies are required to evaluate the concentrations of specific microorganisms in the natural environment in relation to the particulate matter.

  3. AN INDOOR PESTICIDE AIR AND SURFACE CONCENTRATION MODEL

    EPA Science Inventory

    A thorough assessment of human exposure to environmental chemicals requires consideration of all processes in the sequence from source to dose. For assessment of exposure to pesticides following their use indoors, data and models are needed to estimate pesticide concentrations...

  4. Contribution of ship emissions to the concentration and deposition of air pollutants in Europe

    NASA Astrophysics Data System (ADS)

    Aksoyoglu, Sebnem; Baltensperger, Urs; Prévôt, André S. H.

    2016-02-01

    Emissions from the marine transport sector are one of the least-regulated anthropogenic emission sources and contribute significantly to air pollution. Although strict limits were introduced recently for the maximum sulfur content in marine fuels in the SECAs (sulfur emission control areas) and in EU ports, sulfur emissions outside the SECAs and emissions of other components in all European maritime areas have continued to increase in the last two decades. We have used the air quality model CAMx (Comprehensive Air Quality Model with Extensions) with and without ship emissions for the year 2006 to determine the effects of international shipping on the annual as well as seasonal concentrations of ozone, primary and secondary components of PM2.5, and the dry and wet deposition of nitrogen and sulfur compounds in Europe. The largest changes in pollutant concentrations due to ship emissions were predicted for summer. Concentrations of particulate sulfate increased due to ship emissions in the Mediterranean (up to 60 %), the English Channel and the North Sea (30-35 %), while increases in particulate nitrate levels were found especially in the north, around the Benelux area (20 %), where there were high NH3 land-based emissions. Our model results showed that not only are the atmospheric concentrations of pollutants affected by ship emissions, but also depositions of nitrogen and sulfur compounds increase significantly along the shipping routes. NOx emissions from the ships, especially in the English Channel and the North Sea, cause a decrease in the dry deposition of reduced nitrogen at source regions by moving it from the gas phase to the particle phase which then contributes to an increase in the wet deposition at coastal areas with higher precipitation. In the western Mediterranean region, on the other hand, model results show an increase in the deposition of oxidized nitrogen (mostly HNO3) due to the ship traffic. Dry deposition of SO2 seems to be significant along

  5. Effect of air pollution and environmental tobacco smoke on serum hyaluronate concentrations in school children

    PubMed Central

    Fuji, Y; Shima, M; Ando, M; Adachi, M; Tsunetoshi, Y

    2002-01-01

    Objectives: To evaluate serum hyaluronate concentrations relative to air pollution, environmental tobacco smoke (ETS), and respiratory health in Japanese school children. Methods: Respiratory symptoms and serum IgE concentrations were examined in 1037 school children living in four communities in Japan with differing levels of air pollution. Serum hyaluronate concentrations were assayed in 230 children, consisting of all the children who had symptoms of either asthma or wheeze (65 and 50 subjects, respectively) and normal controls adjusted for sex, school grade, and school without these symptoms (115 subjects). Results: Although serum hyaluronate concentrations did not differ for either asthma or wheeze, the concentrations were significantly higher in children living in communities with higher levels of air pollution. Children with asthma or wheeze and those with serum IgE concentrations of 250 IU/ml or above showed differences in hyaluronate concentrations that related to the degree of air pollution in the communities. In children with higher serum IgE concentrations, the hyaluronate concentrations among subjects exposed to ETS were significantly higher than among those without exposure to ETS. Conclusions: The present results suggest that serum hyaluronate concentration is related to the degree of air pollution and exposure to ETS. Children with asthma or wheeze and children with higher IgE concentrations are considered to be more susceptible to environmental factors. PMID:11850556

  6. Limitations of ambient air quality standards in evaluating indoor environments

    SciTech Connect

    Peterson, J.E. )

    1992-03-01

    Analysis of the kinds of data used for the derivation of ambient air quality standards (AAQSs) for carbon monoxide and ozone shows that these values are based on the toxicology of the materials and thus are suitable for evaluating potential health effects of indoor environments, especially on the very young, the aged, and the infirm. A similar analysis shows that the AAQSs for suspended particulate matter, nitrogen dioxide, and sulfur dioxide are strictly empirical and that they should not be used for any but their first, intended purpose. The AAQSs for non-methane hydrocarbons are based on photochemical smog production, not injury of any kind, and have no utility for indoor environment evaluation.

  7. Effect of air preheat temperature and oxygen concentration on flame structure and emission

    SciTech Connect

    Bolz, S.; Gupta, A.K.

    1998-07-01

    The structure of turbulent diffusion flames with highly preheated combustion air (air preheat temperature in excess of 1,150 C) has been obtained using a specially designed regenerative combustion furnace. Propane gas was used as the fuel. Data have been obtained on the global flame features, spectral emission characteristics, spatial distribution of OH, CH and C{sub 2} species, and pollutants emission from the flames. The results have been obtained for various degrees of air preheat temperatures and O{sub 2} concentration in the air. The color of the flame was found to change from yellow to blue to bluish-green to green over the range of conditions examined. In some cases a hybrid color flame was also observed. The recorded images of the flame photographs were analyzed using color-analyzing software. The results show that thermal and chemical flame behavior strongly depends on the air preheat temperature and oxygen content in the air. The flame color was found to be bluish-green or green at very high air preheat temperatures and low-oxygen concentration. However, at high oxygen concentration the flame color was yellow. The flame volume was found to increase with increase in air-preheat temperature and decrease in oxygen concentration. The flame length showed a similar behavior. The concentrations of OH, CH and C{sub 2} increased with an increase in air preheat temperatures. These species exhibited a two-stage combustion behavior at low oxygen concentration and single stage combustion behavior at high oxygen concentration in the air. Stable flames were obtained for remarkably low equivalence ratios, which would not be possible with normal combustion air. Pollutants emission, including CO{sub 2} and NO{sub x} , was much lower with highly preheated combustion air at low O{sub 2} concentration than the normal air. The results also suggest uniform flow and flame thermal characteristics with conditioned highly preheated air. Highly preheated air combustion provides much

  8. 76 FR 6756 - Recommendations Regarding Modifications to the Concentration Limit on Large Financial Companies

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-08

    ... stability, moral hazard in the financial system, the efficiency and competitiveness of United States... Council expects the impact of the concentration limit on moral hazard, competition, and the...

  9. Daily and seasonal variations in radon activity concentration in the soil air.

    PubMed

    Műllerová, Monika; Holý, Karol; Bulko, Martin

    2014-07-01

    Radon activity concentration in the soil air in the area of Faculty of Mathematics, Physics and Informatics (FMPI) in Bratislava, Slovak Republic, has been continuously monitored since 1994. Long-term measurements at a depth of 0.8 m and short-term measurements at a depth of 0.4 m show a high variability in radon activity concentrations in the soil. The analysis of the data confirms that regular daily changes in radon activity concentration in the soil air depend on the daily changes in atmospheric pressure. It was also found that the typical annual courses of the radon activity concentration in the soil air (with summer minima and winter maxima) were disturbed by mild winter and heavy summer precipitation. Influence of precipitation on the increase in the radon activity concentration in the soil air was observed at a depth of 0.4 m and subsequently at a depth of 0.8 m.

  10. Determination of the concentration and isotopic composition of uranium in environmental air filters

    SciTech Connect

    Russ, G.P. III; Bazan, J.M.

    1994-08-26

    For many years, Lawrence Livermore National Laboratory has collected monthly air-particulate filter samples from a variety of environmental monitoring stations on and off site. Historically the concentration and isotopic composition of uranium collected on these filters was determined by isotope dilution using a {sup 233}U spike and thermal ionization mass spectrometry (TIMS). For samples containing as little as 10 nanograms of uranium, ICP-MS is now used to make these measurements to the required level of precision, about 5% in the measured 235/238 and 233/238. Unless particular care is taken to control bias in the mass filter, variable mass bias limits accuracy to a few percent. Measurements of the minor isotopes 236 (if present) and 234 are also possible and provide useful information for identifying the source of the uranium. The advantage of ICP-MS is in rapid analysis, {approximately}12 minutes of instrument time per sample.

  11. Concentration, size, and density of total suspended particulates at the air exhaust of concentrated animal feeding operations.

    PubMed

    Yang, Xufei; Lee, Jongmin; Zhang, Yuanhui; Wang, Xinlei; Yang, Liangcheng

    2015-08-01

    Total suspended particulate (TSP) samples were seasonally collected at the air exhaust of 15 commercial concentrated animal feeding operations (CAFOs; including swine finishing, swine farrowing, swine gestation, laying hen, and tom turkey) in the U.S. Midwest. The measured TSP concentrations ranged from 0.38 ± 0.04 mg m⁻³ (swine gestation in summer) to 10.9 ± 3.9 mg m⁻³ (tom turkey in winter) and were significantly affected by animal species, housing facility type, feeder type (dry or wet), and season. The average particle size of collected TSP samples in terms of mass median equivalent spherical diameter ranged from 14.8 ± 0.5 µm (swine finishing in winter) to 30.5 ± 2.0 µm (tom turkey in summer) and showed a significant seasonal effect. This finding affirmed that particulate matter (PM) released from CAFOs contains a significant portion of large particles. The measured particle size distribution (PSD) and the density of deposited particles (on average 1.65 ± 0.13 g cm⁻³) were used to estimate the mass fractions of PM10 and PM2.5 (PM ≤ 10 and ≤ 2.5 μm, respectively) in the collected TSP. The results showed that the PM10 fractions ranged from 12.7 ± 5.1% (tom turkey) to 21.1 ± 3.2% (swine finishing), whereas the PM2.5 fractions ranged from 3.4 ± 1.9% (tom turkey) to 5.7 ± 3.2% (swine finishing) and were smaller than 9.0% at all visited CAFOs. This study applied a filter-based method for PSD measurement and deposited particles as a surrogate to estimate the TSP's particle density. The limitations, along with the assumptions adopted during the calculation of PM mass fractions, must be recognized when comparing the findings to other studies.

  12. 77 FR 50660 - Limited Approval and Disapproval of Air Quality Implementation Plans; Nevada; Clark County...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-22

    ... INFORMATION: On July 24, 2012 (77 FR 43206), EPA proposed a limited approval and limited disapproval of the... AGENCY 40 CFR Part 52 Limited Approval and Disapproval of Air Quality Implementation Plans; Nevada; Clark... regulations for stationary sources in Clark County, Nevada. DATES: Any comments on this proposal must...

  13. Air quality limit and guide values for sulphur dioxide and suspended particulates - A European community directive.

    PubMed

    Smeets, J

    1982-12-01

    On 15 July, 1980, the Council of Ministers of the European Communities adopted a Council Directive on air quality limit values and guide values for sulphur dioxide and suspended particulates. This directive constitutes the first European legislation on stating air quality standards.The guiding principles underlying this directive are analyzed and the consequences of the directive for Member States, in terms of concrete actions destined to improve the air quality, particularly in highly polluted areas, are indicated. PMID:24264120

  14. Air quality limit and guide values for sulphur dioxide and suspended particulates - A European community directive.

    PubMed

    Smeets, J

    1982-12-01

    On 15 July, 1980, the Council of Ministers of the European Communities adopted a Council Directive on air quality limit values and guide values for sulphur dioxide and suspended particulates. This directive constitutes the first European legislation on stating air quality standards.The guiding principles underlying this directive are analyzed and the consequences of the directive for Member States, in terms of concrete actions destined to improve the air quality, particularly in highly polluted areas, are indicated.

  15. 76 FR 31800 - Airworthiness Directives; Viking Air Limited Model DHC-3 (Otter) Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-02

    ... Policies and Procedures (44 FR 11034, February 26, 1979), (3) Will not affect intrastate aviation in Alaska...-018-AD; Amendment 39-16709; AD 2011-12-02] RIN 2120-AA64 Airworthiness Directives; Viking Air Limited...@faa.gov . SUPPLEMENTARY INFORMATION: Discussion Recent analysis by the FAA on the Viking Air...

  16. 40 CFR 62.14107 - Emission limits for air curtain incinerators.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... incinerators. 62.14107 Section 62.14107 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... 20, 1994 § 62.14107 Emission limits for air curtain incinerators. The owner or operator of an air curtain incinerator with the capacity to combust greater than 250 tons per day of municipal solid...

  17. 40 CFR 62.14107 - Emission limits for air curtain incinerators.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... incinerators. 62.14107 Section 62.14107 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... 20, 1994 § 62.14107 Emission limits for air curtain incinerators. The owner or operator of an air curtain incinerator with the capacity to combust greater than 250 tons per day of municipal solid...

  18. 40 CFR 62.14107 - Emission limits for air curtain incinerators.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... incinerators. 62.14107 Section 62.14107 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... 20, 1994 § 62.14107 Emission limits for air curtain incinerators. The owner or operator of an air curtain incinerator with the capacity to combust greater than 250 tons per day of municipal solid...

  19. 40 CFR 62.14107 - Emission limits for air curtain incinerators.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... incinerators. 62.14107 Section 62.14107 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... 20, 1994 § 62.14107 Emission limits for air curtain incinerators. The owner or operator of an air curtain incinerator with the capacity to combust greater than 250 tons per day of municipal solid...

  20. 40 CFR 62.14107 - Emission limits for air curtain incinerators.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... incinerators. 62.14107 Section 62.14107 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... 20, 1994 § 62.14107 Emission limits for air curtain incinerators. The owner or operator of an air curtain incinerator with the capacity to combust greater than 250 tons per day of municipal solid...

  1. Analysis of Mobile Source Air Toxics (MSATS)–Near-Road VOC and CarbonylConcentrations

    EPA Science Inventory

    This presentation examines data from a year-long study of measured near-road mobile source air toxic (MSAT) concentrations and compares these data with modeled 2005 National Air Toxic Assessment (NATA) results. Field study measurements were collected during a field campaign in ...

  2. EFFECTS OF METAL COMPONENTS IN CONCENTRATED AMBIENT AIR PARTICLES ON PULMONARY INJURY

    EPA Science Inventory

    EFFECTS OF METAL COMPONENTS IN CONCENTRATED AMBIENT AIR PARTICLES ON PULMONARY INJURY. Yuh-Chin Huang, Jackie Stonehuerner, Jackie Carter, Andrew J. Ghio, Robert B. Devlin. NHEERL, US EPA, RTP, NC.
    The mechanisms for cardiopulmonary morbidity associated with exposure to air po...

  3. 40 CFR 52.277 - Oxides of nitrogen, combustion gas concentration limitations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Oxides of nitrogen, combustion gas concentration limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion gas concentration limitations. (a) The following rules are being...

  4. 40 CFR 52.277 - Oxides of nitrogen, combustion gas concentration limitations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 3 2013-07-01 2013-07-01 false Oxides of nitrogen, combustion gas concentration limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion gas concentration limitations. (a) The following rules are being...

  5. 40 CFR 52.277 - Oxides of nitrogen, combustion gas concentration limitations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 3 2014-07-01 2014-07-01 false Oxides of nitrogen, combustion gas concentration limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion gas concentration limitations. (a) The following rules are being...

  6. 40 CFR 52.277 - Oxides of nitrogen, combustion gas concentration limitations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 3 2012-07-01 2012-07-01 false Oxides of nitrogen, combustion gas concentration limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion gas concentration limitations. (a) The following rules are being...

  7. 40 CFR 52.277 - Oxides of nitrogen, combustion gas concentration limitations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 3 2011-07-01 2011-07-01 false Oxides of nitrogen, combustion gas concentration limitations. 52.277 Section 52.277 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Oxides of nitrogen, combustion gas concentration limitations. (a) The following rules are being...

  8. Computational Study of Near-limit Propagation of Detonation in Hydrogen-air Mixtures

    NASA Technical Reports Server (NTRS)

    Yungster, S.; Radhakrishnan, K.

    2002-01-01

    A computational investigation of the near-limit propagation of detonation in lean and rich hydrogen-air mixtures is presented. The calculations were carried out over an equivalence ratio range of 0.4 to 5.0, pressures ranging from 0.2 bar to 1.0 bar and ambient initial temperature. The computations involved solution of the one-dimensional Euler equations with detailed finite-rate chemistry. The numerical method is based on a second-order spatially accurate total-variation-diminishing (TVD) scheme, and a point implicit, first-order-accurate, time marching algorithm. The hydrogen-air combustion was modeled with a 9-species, 19-step reaction mechanism. A multi-level, dynamically adaptive grid was utilized in order to resolve the structure of the detonation. The results of the computations indicate that when hydrogen concentrations are reduced below certain levels, the detonation wave switches from a high-frequency, low amplitude oscillation mode to a low frequency mode exhibiting large fluctuations in the detonation wave speed; that is, a 'galloping' propagation mode is established.

  9. REVIEW OF CONCENTRATION STANDARDS AND GUIDELINES FOR FUNGI IN INDOOR AIR

    EPA Science Inventory

    The paper reviews and compares existing guidelines for indoor airborne fungi, discusses limitations of existing guidelines, and identifies research needs that should contribute to the development of realistic and useful guidelines for these important air pollutants. (NOTE: Exposu...

  10. Air density 2.7 billion years ago limited to less than twice modern levels by fossil raindrop imprints.

    PubMed

    Som, Sanjoy M; Catling, David C; Harnmeijer, Jelte P; Polivka, Peter M; Buick, Roger

    2012-04-19

    According to the 'Faint Young Sun' paradox, during the late Archaean eon a Sun approximately 20% dimmer warmed the early Earth such that it had liquid water and a clement climate. Explanations for this phenomenon have invoked a denser atmosphere that provided warmth by nitrogen pressure broadening or enhanced greenhouse gas concentrations. Such solutions are allowed by geochemical studies and numerical investigations that place approximate concentration limits on Archaean atmospheric gases, including methane, carbon dioxide and oxygen. But no field data constraining ground-level air density and barometric pressure have been reported, leaving the plausibility of these various hypotheses in doubt. Here we show that raindrop imprints in tuffs of the Ventersdorp Supergroup, South Africa, constrain surface air density 2.7 billion years ago to less than twice modern levels. We interpret the raindrop fossils using experiments in which water droplets of known size fall at terminal velocity into fresh and weathered volcanic ash, thus defining a relationship between imprint size and raindrop impact momentum. Fragmentation following raindrop flattening limits raindrop size to a maximum value independent of air density, whereas raindrop terminal velocity varies as the inverse of the square root of air density. If the Archaean raindrops reached the modern maximum measured size, air density must have been less than 2.3 kg m(-3), compared to today's 1.2 kg m(-3), but because such drops rarely occur, air density was more probably below 1.3 kg m(-3). The upper estimate for air density renders the pressure broadening explanation possible, but it is improbable under the likely lower estimates. Our results also disallow the extreme CO(2) levels required for hot Archaean climates. PMID:22456703

  11. Air density 2.7 billion years ago limited to less than twice modern levels by fossil raindrop imprints.

    PubMed

    Som, Sanjoy M; Catling, David C; Harnmeijer, Jelte P; Polivka, Peter M; Buick, Roger

    2012-04-19

    According to the 'Faint Young Sun' paradox, during the late Archaean eon a Sun approximately 20% dimmer warmed the early Earth such that it had liquid water and a clement climate. Explanations for this phenomenon have invoked a denser atmosphere that provided warmth by nitrogen pressure broadening or enhanced greenhouse gas concentrations. Such solutions are allowed by geochemical studies and numerical investigations that place approximate concentration limits on Archaean atmospheric gases, including methane, carbon dioxide and oxygen. But no field data constraining ground-level air density and barometric pressure have been reported, leaving the plausibility of these various hypotheses in doubt. Here we show that raindrop imprints in tuffs of the Ventersdorp Supergroup, South Africa, constrain surface air density 2.7 billion years ago to less than twice modern levels. We interpret the raindrop fossils using experiments in which water droplets of known size fall at terminal velocity into fresh and weathered volcanic ash, thus defining a relationship between imprint size and raindrop impact momentum. Fragmentation following raindrop flattening limits raindrop size to a maximum value independent of air density, whereas raindrop terminal velocity varies as the inverse of the square root of air density. If the Archaean raindrops reached the modern maximum measured size, air density must have been less than 2.3 kg m(-3), compared to today's 1.2 kg m(-3), but because such drops rarely occur, air density was more probably below 1.3 kg m(-3). The upper estimate for air density renders the pressure broadening explanation possible, but it is improbable under the likely lower estimates. Our results also disallow the extreme CO(2) levels required for hot Archaean climates.

  12. USING THE AIR QUALITY MODEL TO ANALYZE THE CONCENTRATIONS OF AIR TOXICS OVER THE CONTINENTAL U.S.

    EPA Science Inventory

    The U.S. Environmental Protection Agency is examining the concentrations and deposition of hazardous air pollutants (HAPs), which include a large number of chemicals, ranging from non reactive (i.e. carbon tetrachloride) to reactive (i.e. formaldehyde), exist in gas, aqueous, and...

  13. Concentrations in air of organobromine, organochlorine and organophosphate flame retardants in Toronto, Canada

    NASA Astrophysics Data System (ADS)

    Shoeib, Mahiba; Ahrens, Lutz; Jantunen, Liisa; Harner, Tom

    2014-12-01

    Concentrations of organobromine (BFRs), organochlorine (CFRs) and organophosphate esters flame retardants and plasticizers (PFRs) in air were monitored for over one year at an urban site in Toronto, Canada during 2010-2011. The mean value for polybrominated diphenyl ethers (BDEs) (gas + particle phase) was 38 pg/m3 with BDE-47 and BDE-99 as the dominant congeners. The mean concentrations in air for ∑non-BDE (BFRs and CFRs), was 9.6 pg/m3 - about four times lower than the BDEs. The brominated FRs: TBP-AE, BTBPE, EH-TBB, BEH-TEBP and the chlorinated syn- and anti-DP were detected frequently, ranging from 87% to 96%. Highest concentrations in air among all flame retardant classes were observed for the Σ-PFRs. The yearly mean concentration in air for ΣPFRs was 2643 pg/m3 with detection frequency higher than 80%. Except for TBP-AE and b- DBE-DBCH, non-BDEs (BFRs, CFRs and PFRs) were mainly associated with the particle phase. BDE concentrations in air were positively correlated with temperature indicating that volatilization from local sources was an important factor controlling levels in air. This correlation did not hold for most BFRs, CFRs and PFRs which were mainly on particles. For these compounds, air concentrations in Toronto are likely related to emissions from point sources and advective inputs. This study highlights the importance of urban air monitoring for FRs. Urban air can be considered a sentinel for detecting changes in the use and application of FRs in commercial products.

  14. LIF measurements of oxygen concentration gradients along flat and wavy air-water interfaces

    NASA Astrophysics Data System (ADS)

    Woodrow, Philip T., Jr.; Duke, Steve R.

    Instantaneous spatially-varying measurements of concentration gradients occurring during aeration for flat, stagnant air-water interfaces and for interfaces with mechanically-generated waves are presented. Measurements were obtained in a laboratory wave tank using a laser-induced fluorescence (LIF) technique that images planar oxygen concentration fields near air-water interfaces. Pulsed nitrogen laser light focused to a thin sheet induces the fluorescence of pyrene butyric acid (in micromolar concentration) in deoxygenated water. The PBA fluorescence is quenched by dissolved oxygen. A high-resolution CCD camera images in two dimensions the intensities of the fluorescence field, providing spatial measurements of oxygen concentration with magnification of 7 μm per pixel. The concentration fields, gradients, and boundary layer thicknesses along the flat and wavy air-water interfaces are quantified and compared to previous measurements associated with sheared gas-liquid interfaces and with wind-generated waves.

  15. Trend and climate signals in seasonal air concentration of organochlorine pesticides over the Great Lakes

    NASA Astrophysics Data System (ADS)

    Gao, Hong; Ma, Jianmin; Cao, Zuohao; Dove, Alice; Zhang, Lisheng

    2010-08-01

    Following worldwide bans or restrictions, the atmospheric level of many organochlorine pesticides (OCPs) over the Great Lakes exhibited a decreasing trend since the 1980s in various environmental compartments. Atmospheric conditions also influence variation and trend of OCPs. In the present study a nonparametric Mann-Kendall test with an additional process to remove the effect of temporal (serial) correlation was used to detect the temporal trend of OCPs in the atmosphere over the Great Lakes region and to examine the statistical significance of the trends. Using extended time series of measured air concentrations over the Great Lakes region from the Integrated Atmospheric Deposition Network, this study also revisits relationships between seasonal mean air concentration of OCPs and major climate variabilities in the Northern Hemisphere. To effectively extract climate signals from the temporal trend of air concentrations, we detrended air concentrations through removing their linear trend, which is driven largely by their respective half-lives in the atmosphere. The interannual variations of the extended time series show a good association with interannual climate variability, notably, the North Atlantic Oscillation (NAO) and the El Niño-Southern Oscillation. This study demonstrates that the stronger climate signals can be extracted from the detrended time series of air concentrations of some legacy OCPs. The detrended concentration time series also help to interpret, in addition to the connection with interannual variation of the NAO, the links between atmospheric concentrations of OCPs and decadal or interdecadal climate change.

  16. An assessment of ozone concentrations within and near the Lake Tahoe Air Basin

    NASA Astrophysics Data System (ADS)

    Dolislager, Leon J.; VanCuren, Richard; Pederson, James R.; Lashgari, Ash; McCauley, Eileen

    2012-01-01

    The Lake Tahoe Atmospheric Deposition Study (LTADS) was conducted by the Air Resources Board of the State of California (CARB) primarily to generate refined estimates of the atmospheric deposition of nitrogen, phosphorous, and particulate matter directly to Lake Tahoe, which straddles the border between the states of California and Nevada near Reno, Nevada. The enhanced air quality monitoring during LTADS also included ozone measurements, which yielded additional insights into atmospheric processes and the role of transport in determining ozone concentrations within the Lake Tahoe Air Basin. The Lake Tahoe Air Basin is located generally downwind of air basins with major emissions of ozone precursors (e.g., VOCs, NOx), capable of generating significant ozone concentrations. Furthermore, vegetation on the western slope of the Sierra Nevada contribute biogenic organic compounds to the air mass. Ozone concentrations within the Tahoe Basin infrequently exceed the local 1-h threshold set to protect forest health (0.08 ppm) and the California 8-h ambient air quality standard (0.070 ppm). A concern then is the potential contribution of regional emission sources to the ozone concentrations observed in the Tahoe Basin. The ozone data collected during LTADS helped to better characterize the relative contribution of local and regional pollution sources to ozone air quality within the Tahoe Basin. The data indicate potential 1- or 2-day intact transport on rare occasions but generally the mixing of the atmosphere over the Sierra Nevada disperses the anthropogenic ozone throughout the boundary layer, which is generally more than a kilometer or two deep during the day. The data analysis indicates that emissions from upwind air basins add to the atmospheric burden of ozone concentrations, raising the regional concentrations in the Sierra Nevada. Given the large background and upwind enhancements relative to the ambient air quality standards, the local contribution does not need to

  17. Modeling indoor air concentrations near emission sources in imperfectly mixed rooms.

    PubMed

    Furtaw, E J; Pandian, M D; Nelson, D R; Behar, J V

    1996-09-01

    Assessments of exposure to indoor air pollutants usually employ spatially well-mixed models which assume homogeneous concentrations throughout a building or room. However, practical experience and experimental data indicate that concentrations are not uniform in rooms containing point sources of emissions; concentrations tend to be greater in close proximity to the source than they are further from it. This phenomenon could account for the observation that "personal air" monitors frequently yield higher concentrations than nearby microenvironmental monitors (i.e., the so-called "personal cloud" effect). In this project, we systematically studied the concentrations of a tracer gas at various distances from its emission source in a controlled-environment, room-size chamber under a variety of ventilation conditions. Measured concentrations in the proximity of the source deviated significantly above the predictions of a conventional well-mixed single-compartment mass balance model. The deviation was found to be a function of distance from the source and total room air flow rate. At typical air flow rates, the average concentration at arm's length (approximately 0.4 meters) from the source exceeds the theoretical well-mixed concentration by a ratio of about 2:1. However, this ratio is not constant; the monitored concentration appears to vary randomly from near the theoretical value to several times above it. Concentration data were fitted to a two-compartment model with the source located in a small virtual compartment within the room compartment. These two compartments were linked with a stochastic air transfer rate parameter. The resulting model provides a more realistic simulation of exposure concentrations than does the well-mixed model for assessing exposure to emissions from active sources. Parameter values are presented for using the enhanced model in a variety of typical situations. PMID:8925388

  18. 10 CFR 835.209 - Concentrations of radioactive material in air.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... concentration (DAC) values given in appendices A and C of this part shall be used in the control of occupational... 10 Energy 4 2012-01-01 2012-01-01 false Concentrations of radioactive material in air. 835.209 Section 835.209 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal...

  19. 10 CFR 835.209 - Concentrations of radioactive material in air.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... concentration (DAC) values given in appendices A and C of this part shall be used in the control of occupational... 10 Energy 4 2011-01-01 2011-01-01 false Concentrations of radioactive material in air. 835.209 Section 835.209 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal...

  20. 10 CFR 835.209 - Concentrations of radioactive material in air.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... concentration (DAC) values given in appendices A and C of this part shall be used in the control of occupational... 10 Energy 4 2013-01-01 2013-01-01 false Concentrations of radioactive material in air. 835.209 Section 835.209 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal...

  1. 10 CFR 835.209 - Concentrations of radioactive material in air.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... concentration (DAC) values given in appendices A and C of this part shall be used in the control of occupational... 10 Energy 4 2014-01-01 2014-01-01 false Concentrations of radioactive material in air. 835.209 Section 835.209 Energy DEPARTMENT OF ENERGY OCCUPATIONAL RADIATION PROTECTION Standards for Internal...

  2. COMPARISON OF MOLD CONCENTRATIONS IN INDOOR AND OUTDOOR AIR SAMPLED SIMULTANEOUSLY AND THEN QUANTIFIED BY MSQPCR

    EPA Science Inventory

    Mold specific quantitative PCR (MSQPCR) was used to measure the concentrations of the 36 mold species in indoor and outdoor air samples that were taken simultaneously for 48 hours in and around 17 homes in Cincinnati, Ohio. The total spore concentrations of 353 per m3...

  3. Air flow and concentration fields at urban road intersections for improved understanding of personal exposure.

    PubMed

    Tiwary, Abhishek; Robins, Alan; Namdeo, Anil; Bell, Margaret

    2011-07-01

    This paper reviews the state of knowledge on modelling air flow and concentration fields at road intersections. The first part covers the available literature from the past two decades on experimental (both field and wind tunnel) and modelling activities in order to provide insight into the physical basis of flow behaviour at a typical cross-street intersection. This is followed by a review of associated investigations of the impact of traffic-generated localised turbulence on the concentration fields due to emissions from vehicles. There is a discussion on the role of adequate characterisation of vehicle-induced turbulence in making predictions using hybrid models, combining the merits of conventional approaches with information obtained from more detailed modelling. This concludes that, despite advancements in computational techniques, there are crucial knowledge gaps affecting the parameterisations used in current models for individual exposure. This is specifically relevant to the growing impetus on walking and cycling activities on urban roads in the context of current drives for sustainable transport and healthy living. Due to inherently longer travel times involved during such trips, compared to automotive transport, pedestrians and cyclists are subjected to higher levels of exposure to emissions. Current modelling tools seem to under-predict this exposure because of limitations in their design and in the empirical parameters employed.

  4. Air flow and concentration fields at urban road intersections for improved understanding of personal exposure.

    PubMed

    Tiwary, Abhishek; Robins, Alan; Namdeo, Anil; Bell, Margaret

    2011-07-01

    This paper reviews the state of knowledge on modelling air flow and concentration fields at road intersections. The first part covers the available literature from the past two decades on experimental (both field and wind tunnel) and modelling activities in order to provide insight into the physical basis of flow behaviour at a typical cross-street intersection. This is followed by a review of associated investigations of the impact of traffic-generated localised turbulence on the concentration fields due to emissions from vehicles. There is a discussion on the role of adequate characterisation of vehicle-induced turbulence in making predictions using hybrid models, combining the merits of conventional approaches with information obtained from more detailed modelling. This concludes that, despite advancements in computational techniques, there are crucial knowledge gaps affecting the parameterisations used in current models for individual exposure. This is specifically relevant to the growing impetus on walking and cycling activities on urban roads in the context of current drives for sustainable transport and healthy living. Due to inherently longer travel times involved during such trips, compared to automotive transport, pedestrians and cyclists are subjected to higher levels of exposure to emissions. Current modelling tools seem to under-predict this exposure because of limitations in their design and in the empirical parameters employed. PMID:21435722

  5. Upward excursion limits from air saturation at 5 ATA (Atmospheres Absolute)

    NASA Astrophysics Data System (ADS)

    Parker, James W.

    1989-01-01

    Present USN submarine rescue capability makes a prolonged exposure of the submarine crew to hyperbaric air a distinct possibility. The exposure may be to pressures as great as 5 atmospheres absolute (ATA), and for periods of time of up to 72 hours. A series of experimental dives were conducted to establish the safe, upward excursion from 5 ATA (132 FSWG); that is, the maximum, immediate reduction in pressure which these individuals can safely tolerate. This specifies the required pressure in the compartment of a mother submarine to which the rescued personnel would be transferred. In order to minimize the effects of pulmonary oxygen toxicity, the limits first were established using a nitrox equivalent of air at 5 ATA. The upward limit from 4.36 ATA (111 FSWG) was found to be 2.97 ATA (65 FSWG). Once this limit had been set, a series of dives were conducted to test this up limit from standard air at 5 ATA.

  6. Variations of 210Pb concentrations in surface air at Thessaloniki, Greece (40°N)

    NASA Astrophysics Data System (ADS)

    Ioannidou, A.; Kotsopoulou, E.; Karanatsiou, A.; Papastefanou, C.

    2012-04-01

    Atmospheric concentrations of 210Pb were measured over the year 2009 in ground level air at Thessaloniki, Northern Greece (40°62' N, 22°95'E). The mean activity concentrations of 210Pb in surface air have been found to be 671 ± 213 μBq m-3. The highest values of monthly atmospheric concentrations of 210Pb were observed in the autumn and the lowest in the spring period. The higher values of 210Pb during autumn were attributed to frequent inversion conditions of the surface layers, resulting in an enrichment of radon and its decay products in surface air. The lower values during the winter months might be due to the low emanation of radon from the frozen or snow-covered soil. The minima of 210Pb concentrations during spring might reflect on higher washout during this period, which results in less emanation of radon from saturated with water soil, resulting in less production of 210Pb near ground-level air. The relative high values during summer are probably due to the higher 222Rn exhalation from the ground and due to the higher air mixing within the troposphere, which has as a result to carry down to the surface layer 210Pb whose origin is older air masses which entered into the free troposphere.

  7. A Method for Estimating Urban Background Concentrations in Support of Hybrid Air Pollution Modeling for Environmental Health Studies

    PubMed Central

    Arunachalam, Saravanan; Valencia, Alejandro; Akita, Yasuyuki; Serre, Marc L.; Omary, Mohammad; Garcia, Valerie; Isakov, Vlad

    2014-01-01

    Exposure studies rely on detailed characterization of air quality, either from sparsely located routine ambient monitors or from central monitoring sites that may lack spatial representativeness. Alternatively, some studies use models of various complexities to characterize local-scale air quality, but often with poor representation of background concentrations. A hybrid approach that addresses this drawback combines a regional-scale model to provide background concentrations and a local-scale model to assess impacts of local sources. However, this approach may double-count sources in the study regions. To address these limitations, we carefully define the background concentration as the concentration that would be measured if local sources were not present, and to estimate these background concentrations we developed a novel technique that combines space-time ordinary kriging (STOK) of observations with outputs from a detailed chemistry-transport model with local sources zeroed out. We applied this technique to support an exposure study in Detroit, Michigan, for several pollutants (including NOx and PM2.5), and evaluated the estimated hybrid concentrations (calculated by combining the background estimates that addresses this issue of double counting with local-scale dispersion model estimates) using observations. Our results demonstrate the strength of this approach specifically by eliminating the problem of double-counting reported in previous hybrid modeling approaches leading to improved estimates of background concentrations, and further highlight the relative importance of NOx vs. PM2.5 in their relative contributions to total concentrations. While a key limitation of this approach is the requirement for another detailed model simulation to avoid double-counting, STOK improves the overall characterization of background concentrations at very fine spatial scales. PMID:25321872

  8. Historical Occupational Trichloroethylene Air Concentrations Based on Inspection Measurements From Shanghai, China

    PubMed Central

    Friesen, Melissa C.; Locke, Sarah J.; Chen, Yu-Cheng; Coble, Joseph B.; Stewart, Patricia A.; Ji, Bu-Tian; Bassig, Bryan; Lu, Wei; Xue, Shouzheng; Chow, Wong-Ho; Lan, Qing; Purdue, Mark P.; Rothman, Nathaniel; Vermeulen, Roel

    2015-01-01

    Purpose: Trichloroethylene (TCE) is a carcinogen that has been linked to kidney cancer and possibly other cancer sites including non-Hodgkin lymphoma. Its use in China has increased since the early 1990s with China’s growing metal, electronic, and telecommunications industries. We examined historical occupational TCE air concentration patterns in a database of TCE inspection measurements collected in Shanghai, China to identify temporal trends and broad contrasts among occupations and industries. Methods: Using a database of 932 short-term, area TCE air inspection measurements collected in Shanghai worksites from 1968 through 2000 (median year 1986), we developed mixed-effects models to evaluate job-, industry-, and time-specific TCE air concentrations. Results: Models of TCE air concentrations from Shanghai work sites predicted that exposures decreased 5–10% per year between 1968 and 2000. Measurements collected near launderers and dry cleaners had the highest predicted geometric means (GM for 1986 = 150–190mg m−3). The majority (53%) of the measurements were collected in metal treatment jobs. In a model restricted to measurements in metal treatment jobs, predicted GMs for 1986 varied 35-fold across industries, from 11mg m−3 in ‘other metal products/repair’ industries to 390mg m–3 in ‘ships/aircrafts’ industries. Conclusions: TCE workplace air concentrations appeared to have dropped over time in Shanghai, China between 1968 and 2000. Understanding differences in TCE concentrations across time, occupations, and industries may assist future epidemiologic studies in China. PMID:25180291

  9. Indoor air polychlorinated biphenyl concentrations in three communities along the Upper Hudson River, New York.

    PubMed

    Wilson, Lloyd R; Palmer, Patrick M; Belanger, Erin E; Cayo, Michael R; Durocher, Lorie A; Hwang, Syni-An A; Fitzgerald, Edward F

    2011-10-01

    Indoor air polychlorinated biphenyl (PCB) concentrations were measured in upstate New York as part of a nonoccupational exposure investigation. The adjacent study communities contain numerous sites of current and former PCB contamination, including two capacitor-manufacturing facilities. Indoor air PCB concentrations in the study area homes were not significantly different than in the comparison area homes. Total PCB concentrations in the study area homes ranged from 0.3 to 114.3 ng/m(3) (median 7.9). For the comparison area homes, concentrations ranged from 0.3 to 233.3 ng/m(3) (median 6.8). No correlations were found between PCB concentrations in indoor and outdoor air, with indoor concentrations generally 20 times higher than outdoor concentrations. Of the home characteristics cataloged, the presence of fluorescent lights was significantly associated with total PCB concentration in the study area only. The indoor PCB concentrations measured in this study are similar to those in other communities with known PCB-contaminated sites and similar to levels reported in other locations from the northeastern United States. PMID:21136249

  10. Membrane-associated polypeptides induced in Chlamydomonas by limiting CO sub 2 concentrations

    SciTech Connect

    Spalding, M.H.; Jeffrey, M. )

    1989-01-01

    Chlamydomonas reinhardtii and other unicellular green algae have a high apparent affinity for CO{sub 2}, little O{sub 2} inhibition of photosynthesis, and reduced photorespiration. These characteristics result from operation of a CO{sub 2}-concentrating system. The CO{sub 2}-concentrating system involves active inorganic carbon transport and is under environmental control. Cells grown at limiting CO{sub 2} concentrations have inorganic carbon transport activity, but cells grown at 5% CO{sub 2} do not. Four membrane-associated polypeptides (M{sub r}, 19, 21, 35, and 36 kilodaltons) have been identified which either appear or increase in abundance during adaptation to limiting CO{sub 2} concentrations. The appearance of two of the polypeptides occurs over roughly the same time course as the appearance of the CO{sub 2}-concentrating system activity in response to CO{sub 2} limitation.

  11. Temperature Programmed Desorption of Quench-condensed Krypton and Acetone in Air; Selective Concentration of Ultra-trace Gas Components.

    PubMed

    Suzuki, Taku T; Sakaguchi, Isao

    2016-01-01

    Selective concentration of ultra-trace components in air-like gases has an important application in analyzing volatile organic compounds in the gas. In the present study, we examined quench-condensation of the sample gas on a ZnO substrate below 50 K followed by temperature programmed desorption (TPD) (low temperature TPD) as a selective gas concentration technique. We studied two specific gases in the normal air; krypton as an inert gas and acetone as a reactive gas. We evaluated the relationship between the operating condition of low temperature TPD and the lowest detection limit. In the case of krypton, we observed the selective concentration by exposing at 6 K followed by thermal desorption at about 60 K. On the other hand, no selectivity appeared for acetone although trace acetone was successfully concentrated. This is likely due to the solvent effect by a major component in the air, which is suggested to be water. We suggest that pre-condensation to remove the water component may improve the selectivity in the trace acetone analysis by low temperature TPD.

  12. Temperature Programmed Desorption of Quench-condensed Krypton and Acetone in Air; Selective Concentration of Ultra-trace Gas Components.

    PubMed

    Suzuki, Taku T; Sakaguchi, Isao

    2016-01-01

    Selective concentration of ultra-trace components in air-like gases has an important application in analyzing volatile organic compounds in the gas. In the present study, we examined quench-condensation of the sample gas on a ZnO substrate below 50 K followed by temperature programmed desorption (TPD) (low temperature TPD) as a selective gas concentration technique. We studied two specific gases in the normal air; krypton as an inert gas and acetone as a reactive gas. We evaluated the relationship between the operating condition of low temperature TPD and the lowest detection limit. In the case of krypton, we observed the selective concentration by exposing at 6 K followed by thermal desorption at about 60 K. On the other hand, no selectivity appeared for acetone although trace acetone was successfully concentrated. This is likely due to the solvent effect by a major component in the air, which is suggested to be water. We suggest that pre-condensation to remove the water component may improve the selectivity in the trace acetone analysis by low temperature TPD. PMID:27063719

  13. Air-vegetation exchange of SOCs as a control of atmospheric concentrations and residence times

    SciTech Connect

    Hornbuckle, K.C.; Eisenreich, S.J.

    1994-12-31

    Semi-volatile organic compounds (SOCs) such as the polychlorinated biphenyls exhibit seasonal maxima in atmospheric concentrations with highest values in the warm summer. This generally believed to result from the effect of temperature on SOC vapor pressure with direct and important implications to global transport. The authors have conducted a series of field experiments whereby air samples were collected above an ombrotrophic, forested bog in northern MN at a frequency of 6 day{sup {minus}1} during the fall, winter, spring and summer. Samples of Sphagnum moss and other vegetation were also collected on each occasion. All samples were analyzed for PCBs, low MW PAHs, gaseous hydrocarbons and selected pesticides. Meteorological and soils data were collected during all experiments (air and soil temperature, wind direction and velocity, RH). Diurnal concentration data, air-plant and air-soil partition coefficients and probable mechanisms and kinetics of SOC-plant interactions will be presented.

  14. Variability of concentrations of polybrominated diphenyl ethers and polychlorinated biphenyls in air: implications for monitoring, modeling and control

    NASA Astrophysics Data System (ADS)

    Gouin, T.; Harner, T.; Daly, G. L.; Wania, F.; Mackay, D.; Jones, K. C.

    Monitoring data indicate that organic compounds with high octanol-air partition coefficients ( KOA), such as polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) exhibit seasonally variable air concentrations, especially during early spring, shortly after snow melt and before bud-burst when levels are elevated. This variability can complicate the interpretation of monitoring data designed to assess year-to-year changes. It is suggested that relatively simple dynamic multimedia mass balance models can assist interpretation by "factoring out" variability attributable to temperature and other seasonal effects as well as identifying likely contaminant sources. To illustrate this approach, high-volume air samples were collected from January to June, 2002 at a rural location in southern Ontario. Gas-phase concentrations for both ΣPBDE and ΣPCB rose from below the detection limit during the winter to 19 and 110 pg m -3, respectively, in early spring, only to decrease again following bud-burst. Passive air samples (PAS), deployed at seven urban, rural and remote sites for two one-month periods prior and following bud-burst, indicate a strong urban-rural gradient for both the PBDEs and PCBs. Calculated air concentrations from the PAS are shown to agree favorably with the high-volume air sampling data, with concentrations ranging 6-85 pg m -3 and 6-360 pg m -3 for ΣPBDE and ΣPCB, respectively. Concentrations in urban areas are typically 5 times greater than in rural locations. These data were interpreted using simulation results from a fate model including a seasonally variable forest canopy and snow pack, suggesting that the primary source is urban and that the "spring pulse" is the result of several interacting factors. Such contaminants are believed to be efficiently deposited in winter, accumulate in the snow pack and are released to terrestrial surfaces upon snow melt in spring. Warmer temperatures cause volatilization and a rise in air

  15. Modeling the Concentrations of On-Road Air Pollutants in Southern California

    PubMed Central

    Li, Lianfa; Wu, Jun; Hudda, Neelakshi; Sioutas, Constantinos; Fruin, Scott A.; Delfino, Ralph J.

    2014-01-01

    High concentrations of air pollutants on roadways, relative to ambient concentrations, contribute significantly to total personal exposure. Estimation of these exposures requires measurements or prediction of roadway concentrations. Our study develops, compares and evaluates linear regression and non-linear generalized additive models (GAMs) to estimate on-road concentrations of four key air pollutants, particle-bound polycyclic aromatic hydrocarbons (PB-PAH), particle number count (PNC), nitrogen oxides (NOx), and particulate matter with diameter <2.5 μm (PM2.5) using traffic, meteorology, and elevation variables. Critical predictors included wind speed and direction for all the pollutants, traffic-related variables for PB-PAH, PNC, and NOx, and air temperatures and relative humidity for PM2.5. GAMs explained 50%, 55%, 46%, and 71% of the variance for log or square-root transformed concentrations of PB-PAH, PNC, NOx, and PM2.5 respectively, an improvement of 5 to over 15% over the linear models. Accounting for temporal autocorrelation in the GAMs further improved the prediction, explaining 57-89% of the variance. We concluded that traffic and meteorological data are good predictors in estimating on-road traffic-related air pollutant concentrations and GAMs perform better for non-linear variables, such as meteorological parameters. PMID:23859442

  16. Effects of the Deregulation on the Concentration of the Brazilian Air Transportation Industry

    NASA Technical Reports Server (NTRS)

    Guterres, Marcelo Xavier; Muller, Carlos

    2003-01-01

    This paper addresses the effects of the deregulation of the Brazilian air transportation industry in terms of the concentration of the market. We will show some metrics that are commonly used to study the concentration of the industry. This paper uses the Herfindhal- Hirschman Index. This index tends to zero in the competitive scenario, with a large number of small firms, and to one in case of a monopolistic scenario. The paper analyses the dynamics of the concentration of the Brazilian domestic air transportation market, in order to evaluate the effects of deregulation. We conclude that the Brazilian market presents oligopoly characteristics and aspects in its current structure that maintain the market concentrated in spite of the Deregulation measures adopted by the aeronautical authority. Keywords: Herfindhal-Hirschman Index, concentration, Deregulation

  17. Influence of indoor air conditions on radon concentration in a detached house.

    PubMed

    Akbari, Keramatollah; Mahmoudi, Jafar; Ghanbari, Mahdi

    2013-02-01

    Radon is released from soil and building materials and can accumulate in residential buildings. Breathing radon and radon progeny for extended periods hazardous to health and can lead to lung cancer. Indoor air conditions and ventilation systems strongly influence indoor radon concentrations. This paper focuses on effects of air change rate, indoor temperature and relative humidity on indoor radon concentrations in a one family detached house in Stockholm, Sweden. In this study a heat recovery ventilation system unit was used to control the ventilation rate and a continuous radon monitor (CRM) was used to measure radon levels. FLUENT, a computational fluid dynamics (CFD) software package was used to simulate radon entry into the building and air change rate, indoor temperature and relative humidity effects using a numerical approach. The results from analytical solution, measurements and numerical simulations showed that air change rate, indoor temperature and moisture had significant effects on indoor radon concentration. Increasing air change rate reduces radon level and for a specific air change rate (in this work Ach = 0.5) there was a range of temperature and relative humidity that minimized radon levels. In this case study minimum radon levels were obtained at temperatures between 20 and 22 °C and a relative humidity of 50-60%.

  18. Influence of indoor air conditions on radon concentration in a detached house.

    PubMed

    Akbari, Keramatollah; Mahmoudi, Jafar; Ghanbari, Mahdi

    2013-02-01

    Radon is released from soil and building materials and can accumulate in residential buildings. Breathing radon and radon progeny for extended periods hazardous to health and can lead to lung cancer. Indoor air conditions and ventilation systems strongly influence indoor radon concentrations. This paper focuses on effects of air change rate, indoor temperature and relative humidity on indoor radon concentrations in a one family detached house in Stockholm, Sweden. In this study a heat recovery ventilation system unit was used to control the ventilation rate and a continuous radon monitor (CRM) was used to measure radon levels. FLUENT, a computational fluid dynamics (CFD) software package was used to simulate radon entry into the building and air change rate, indoor temperature and relative humidity effects using a numerical approach. The results from analytical solution, measurements and numerical simulations showed that air change rate, indoor temperature and moisture had significant effects on indoor radon concentration. Increasing air change rate reduces radon level and for a specific air change rate (in this work Ach = 0.5) there was a range of temperature and relative humidity that minimized radon levels. In this case study minimum radon levels were obtained at temperatures between 20 and 22 °C and a relative humidity of 50-60%. PMID:23159846

  19. The effects of forced air flow and oxygen concentration on flammability, smoke density, and pyrolytic toxicity

    NASA Technical Reports Server (NTRS)

    Sauers, D. G.

    1976-01-01

    The question is posed whether forced air flow should be incorporated into flammability tests as a relevant variable. A test apparatus is described which permits tests to be conducted on small test specimens in a forced flow which is (continuously) variable over flow velocities from zero to 300 feet per minute (1.52 m/s). The effects of air-flow rate and oxygen concentration on flame propagation rate, maximum smoke density, and pyrolytic product toxicity were measured for a single material and were statistically evaluated. Regression analysis was used to graph the resulting relationships. It is concluded that air velocity is an important variable for laboratory flammability testing.

  20. Preliminary assessment of BTEX concentrations in indoor air of residential buildings and atmospheric ambient air in Ardabil, Iran

    NASA Astrophysics Data System (ADS)

    Hazrati, Sadegh; Rostami, Roohollah; Farjaminezhad, Manoochehr; Fazlzadeh, Mehdi

    2016-05-01

    BTEX concentrations in indoor and outdoor air of 50 homes were studied in Ardabil city and their influencing parameters including; heating system, using gas stove and samovar, tobacco smoking, the floors in which the monitored homes were located, and kitchen plan were considered in the study. Risk assessment analysis was carried out with the obtained concentrations based on EPA IRIS reference doses. BTEX compounds were sampled by charcoal tubes and the samples were analyzed by a GC-FID. Concentrations of benzene (15.18 μg/m3 vs. 8.65 μg/m3), toluene (69.70 μg/m3 vs. 40.56 μg/m3), ethylbenzene (12.07 μg/m3 vs. 4.92 μg/m3) and xylene (48.08 μg/m3 vs. 7.44 μg/m3) in indoor air were significantly (p < 0.05) higher than the levels quantified for outdoor air. The obtained concentrations of benzene were considerably higher than the recommended value of 5 μg/m3 established by Iran environmental protection organization. Among the BTEX compounds, benzene (HQ = 0.51) and xylene (HQ = 0.47) had notable hazard quotient and were the main pollutants responsible for high hazard index in the monitored homes (HI = 1.003). The results showed considerably high cancer risk for lifetime exposure to the indoor (125 × 10-6) and outdoor (71 × 10-6) benzene. Indoor benzene concentrations in homes were significantly influenced by type of heating system, story, and natural gas appliances.

  1. [Estimation of average traffic emission factor based on synchronized incremental traffic flow and air pollutant concentration].

    PubMed

    Li, Run-Kui; Zhao, Tong; Li, Zhi-Peng; Ding, Wen-Jun; Cui, Xiao-Yong; Xu, Qun; Song, Xian-Feng

    2014-04-01

    On-road vehicle emissions have become the main source of urban air pollution and attracted broad attentions. Vehicle emission factor is a basic parameter to reflect the status of vehicle emissions, but the measured emission factor is difficult to obtain, and the simulated emission factor is not localized in China. Based on the synchronized increments of traffic flow and concentration of air pollutants in the morning rush hour period, while meteorological condition and background air pollution concentration retain relatively stable, the relationship between the increase of traffic and the increase of air pollution concentration close to a road is established. Infinite line source Gaussian dispersion model was transformed for the inversion of average vehicle emission factors. A case study was conducted on a main road in Beijing. Traffic flow, meteorological data and carbon monoxide (CO) concentration were collected to estimate average vehicle emission factors of CO. The results were compared with simulated emission factors of COPERT4 model. Results showed that the average emission factors estimated by the proposed approach and COPERT4 in August were 2.0 g x km(-1) and 1.2 g x km(-1), respectively, and in December were 5.5 g x km(-1) and 5.2 g x km(-1), respectively. The emission factors from the proposed approach and COPERT4 showed close values and similar seasonal trends. The proposed method for average emission factor estimation eliminates the disturbance of background concentrations and potentially provides real-time access to vehicle fleet emission factors.

  2. Laser induced fluorescence measurements of dissolved oxygen concentration fields near air bubble surfaces

    NASA Astrophysics Data System (ADS)

    Roy, Sabita; Duke, Steve R.

    2000-09-01

    This article describes a laser-induced fluorescence (LIF) technique for measuring dissolved oxygen concentration gradients in water near the surface of an air bubble. Air bubbles are created at the tip of a needle in a rectangular bubble column filled with water that contains pyrenebutyric acid (PBA). The fluorescence of the PBA is induced by a planar pulse of nitrogen laser light. Oxygen transferring from the air bubble to the deoxygenated water quenches the fluorescence of the PBA. Images of the instantaneous and two-dimensional fluorescence field are obtained by a UV-intensified charge-coupled device (CCD) camera. Quenching of fluorescence intensity is determined at each pixel in the CCD image to measure dissolved oxygen concentration. Two-dimensional concentration fields are presented for a series of measurements of oxygen transfer from 1.6 mm bubbles suspended on the tip of a needle in a quiescent fluid. The images show the spatially varying concentration profiles, gradients, and boundary layer thicknesses at positions around the bubble surfaces. These direct and local measurements of concentration behavior within the mass transfer boundary layer show the potential of this LIF technique for the development of general and mechanistic models for oxygen transport across the air-water interface.

  3. [Concentrations and influencing factors of gaseous polycyclic aromatic hydrocarbons in residential air in Beijing].

    PubMed

    Wei, Zhi-cheng; Chang, Biao; Qiu, Wei-xun; Wang, Yi; Wu, Shi-min; Xing, Bao-shan; Liu, Wen-xin; Tao, Shu

    2007-09-01

    7 gas phase PAHs components in indoor air collected from 38 families were investigated by modified passive air samplers in Beijing areas during the local heating and non-heating seasons, and the influencing factors were discussed as well. The analytical results indicate that the gasous PAHs in local indoor air are dominated by 2 and 3 rings compounds, the mean concentrations for the 7 individual gaseous components range from 1 to 40 ng/m3, and the average concentration of total gaseous PAHs is about 100 ng/m3. There is no significant difference in total gaseous PAHs concentrations between the heating and the non-heating seasons, while some apparent seasonal changes occur in ACY and FLA concentrations. Compared with heating season, contribution of 2 rings compounds decreases while the proportions of 3 and 4 rings species increase during the non-heating season. Based on household activity questionnaires and actual analytical concentrations, the main influencing factors accounted for gaseous PAHs in indoor air, identified by multifactor analysis of variance, include cigarette smoking, use of moth ball, intensity of draft, cuisine frequency and built age.

  4. Comparison of mold concentrations quantified by MSQPCR in indoor and outdoor air sampled simultaneously

    SciTech Connect

    Meklin, Teija; Reponen, Tina; McKinstry, Craig A.; Cho, Seung H.; Grinshpun, Sergey A.; Nevalainen, Aino; Vepsalainen, Asko; Haugland, Richard A.; Lemasters, Grace; Vesper, Sephen J.

    2007-08-15

    Mold specific quantitative PCR (MSQPCR) was used to measure the concentrations of 36 mold species in dust and in indoor and in outdoor air samples that were taken simultaneously in 17 homes in Cincinnati with no-known water damage. The total spore concentrations in the indoor (I) and outdoor (O) air samples were statistically significantly different and the concentrations in the three sample types of many of the individual species were significantly different (p < 0.05 based on the Wilcoxon Signed Rank Test). The I/O ratios of the averages or geometric means of the individual species were generally less than 1; but these I/O ratios were quite variable ranging from 0.03 for A. sydowii to 1.2 for Acremonium strictum. There were no significant correlations for the 36 specific mold concentrations between the dust samples and the indoor or outdoor air samples (based on the Spearman’s Rho test). The indoor and outdoor air concentrations of 32 of the species were not correlated. Only Aspergillus penicillioides, C. cladosporioides types 1 and 2 and C. herbarum had sufficient data to estimate a correlation at rho > 0.5 with signicance (p < 0.05) In six of these homes, a previous dust sample had been collected and analyzed 2 years earlier. The ERMI© values for the dust samples taken in the same home two years apart were not significantly different (p=0.22) based on Wilcoxon Signed Rank Test.

  5. Concentration multiplicity in a draft tube fluidized-bed bioreactor involving two limiting substrates.

    PubMed

    Tong, C C; Fan, L S

    1988-01-01

    Concentration multiplicity in a two-phase or three-phase draft tube fluidized-bed bioreactor containing biofloc particles is studied. The kinetics of biological reactions considered involve two limiting substrates. The necessary and sufficient conditions for concentration multiplicity in both the biofilm and bioreactor are examined in terms of effectiveness factor, inlet and bulk concentration of substrates, and liquid flow rate. Hysteresis behavior in both the biofilm and bioreactor and multiplicity of concentration profiles in the biofilm are also discussed. PMID:18581559

  6. Ambient concentrations and personal exposure to polycyclic aromatic hydrocarbons (PAH) in an urban community with mixed sources of air pollution

    PubMed Central

    ZHU, XIANLEI; FAN, ZHIHUA (TINA); WU, XIANGMEI; JUNG, KYUNG HWA; OHMAN-STRICKLAND, PAMELA; BONANNO, LINDA J.; LIOY, PAUL J.

    2014-01-01

    Assessment of the health risks resulting from exposure to ambient polycyclic aromatic hydrocarbons (PAH) is limited by a lack of environmental exposure data among the general population. This study characterized personal exposure and ambient concentrations of PAH in the Village of Waterfront South (WFS), an urban community with many mixed sources of air toxics in Camden, New Jersey, and CopeWood/Davis Streets (CDS), an urban reference area located ~1 mile east of WFS. A total of 54 and 53 participants were recruited from non-smoking households in WFS and CDS, respectively. In all, 24-h personal and ambient air samples were collected simultaneously in both areas on weekdays and weekends during summer and winter. The ambient PAH concentrations in WFS were either significantly higher than or comparable to those in CDS, indicating the significant impact of local sources on PAH pollution in WFS. Analysis of diagnostic ratios and correlation suggested that diesel truck traffic, municipal waste combustion and industrial combustion were the major sources in WFS. In such an area, ambient air pollution contributed significantly to personal PAH exposure, explaining 44–96% of variability in personal concentrations. This study provides valuable data for examining the impact of local ambient PAH pollution on personal exposure and therefore potential health risks associated with environmental PAH pollution. PMID:21364704

  7. Monitor of the concentration of particles of dense radioactive materials in a stream of air

    DOEpatents

    Yule, Thomas J.

    1979-01-01

    A monitor of the concentration of particles of radioactive materials such as plutonium oxide in diameters as small as 1/2 micron includes in combination a first stage comprising a plurality of virtual impactors, a second stage comprising a further plurality of virtual impactors, a collector for concentrating particulate material, a radiation detector disposed near the collector to respond to radiation from collected material and means for moving a stream of air, possibly containing particulate contaminants, through the apparatus.

  8. Setting limits: Using air pollution thresholds to protect and restore US ecosystems

    USGS Publications Warehouse

    Fenn, Mark E.; Lambert, Kathleen F.; Blett, Tamara F.; Burns, Douglas A.; Pardo, Linda H.; Lovett, Gary M.; Haeuber, Richard A.; Evers, David C.; Driscoll, Charles T.; Jeffries, Dean S.

    2011-01-01

    More than four decades of research provide unequivocal evidence that sulfur, nitrogen, and mercury pollution have altered, and will continue to alter, our nation's lands and waters. The emission and deposition of air pollutants harm native plants and animals, degrade water quality, affect forest productivity, and are damaging to human health. Many air quality policies limit emissions at the source but these control measures do not always consider ecosystem impacts. Air pollution thresholds at which ecological effects are observed, such as critical loads, are effective tools for assessing the impacts of air pollution on essential ecosystem services and for informing public policy. U.S. ecosystems can be more effectively protected and restored by using a combination of emissions-based approaches and science-based thresholds of ecosystem damage.

  9. Application of hybrid coagulation microfiltration with air backflushing to direct sewage concentration for organic matter recovery.

    PubMed

    Jin, Zhengyu; Gong, Hui; Wang, Kaijun

    2015-01-01

    The idea of sewage concentration is gradually being accepted as a promising and sustainable way of wastewater resource recovery. In this study, Hybrid coagulation microfiltration (HCM) with air backflushing (AB) was investigated to effectively concentrate organic matter. Compared to direct sewage microfiltration, the addition of coagulation process improved the filtration performance with less fouling trends and better concentration efficiency. The use of AB exhibited even better performance within the same 7-h preliminary concentration period by reducing to one tenth of the resistance and collecting around four times as much organic matter into the product concentrate as in direct sewage microfiltration. During 93-h lab-scale continuous concentration by HCM with AB, a product concentrate with the COD concentration over 15,000 mg/L was achieved and around 70% of total influent organic matter could be recovered. Compared to Direct Membrane Filtration (DMF) with Chemically Enhanced Backwash (CEB), HCM with AB achieved better concentration efficiency with higher concentration extent and concentration velocity along with less organic matter mineralization and the more concentrated product despite with lower organic matter retention. HCM with AB could be a promising effective sewage organic matter concentration for resource recovery under optimization.

  10. 75 FR 43092 - Airworthiness Directives; Viking Air Limited (Type Certificate Previously Held by Bombardier, Inc...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-23

    ... transport airplanes, including the adequacy of existing regulations, the service history of airplanes... Directives; Viking Air Limited (Type Certificate Previously Held by Bombardier, Inc.) Model DHC-7 Airplanes... may review copies of the referenced service information at the FAA, Transport Airplane...

  11. Analysis of yellow-tip limits in methane-air flames

    SciTech Connect

    Folga, S.M.

    1986-01-01

    Rational design of safe domestic burners requires estimation of yellow-tip limits, which have traditionally indicated limits of safe operation. A bunsen-burner system that allowed for variations in the burner dimensions was constructed to collect overall composition data within yellow-tip limit methane-air flames. Direct measurement of the overall composition at the yellow-tip proved that the yellow-tip corresponds to a particular composition regardless of operating conditions for a given fuel-air system; the value of the characteristic composition for laminar methane-air flames was determined to Phi = 1.29. Composition profiles were determined within two yellow-tip limit methane-air flames. The luminous flame surface is the surface were CH/sub 4/ is consumed completely to form incomplete products of combustion; it is not of constant composition, being nearer to stoichiometric (Phi = 1) near the burner port. The outer cone is associated with the burnout of CO to form CO/sub 2/; like the luminous flame surface, it is not of constant composition. Near the burner port, the outer cone is slightly fuel-lean (Phi = 0.9) with the composition at the counter cone height as Phi = 1.

  12. 76 FR 34011 - Airworthiness Directives; Viking Air Limited (Type Certificate No. A-815 Formerly Held by...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-10

    ... 2011-05-02, Amendment 39-16611 (76 FR 10220, February 24, 2011), for certain Viking Air Limited (Type...-05-02, Amendment 39-16611 (76 FR 10220, February 24, 2011), and adding the following new AD: Viking... a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February...

  13. A Comparison of Statistical Techniques for Combining Modeled and Observed Concentrations to Create High-Resolution Ozone Air Quality Surfaces

    EPA Science Inventory

    Air quality surfaces representing pollutant concentrations across space and time are needed for many applications, including tracking trends and relating air quality to human and ecosystem health. The spatial and temporal characteristics of these surfaces may reveal new informat...

  14. Effect of geocoding errors on traffic-related air pollutant exposure and concentration estimates

    EPA Science Inventory

    Exposure to traffic-related air pollutants is highest very near roads, and thus exposure estimates are sensitive to positional errors. This study evaluates positional and PM2.5 concentration errors that result from the use of automated geocoding methods and from linearized approx...

  15. Performance of the Proposed New Federal Reference Methods for Measuring Ozone Concentrations in Ambient Air

    EPA Science Inventory

    The current Federal Reference Method (FRM) for measuring concentrations of ozone in ambient air, described in EPA regulations at 40 CFR Part 50, Appendix D, is based on the dry, gas-phase, chemiluminescence reaction between ethylene (C2H4) and any ozone (O

  16. Modeling and Impacts of Traffic Emissions on Air Toxics Concentrations near Roadways

    EPA Science Inventory

    The dispersion formulation incorporated in the U.S. Environmental Protection Agency’s AERMOD regulatory dispersion model is used to estimate the contribution of traffic-generated emissions of select VOCs – benzene, 1,3-butadiene, toluene – to ambient air concentrations at downwin...

  17. Evaluation and Comparison of Chemiluminescence and UV Photometric Methods for Measuring Ozone Concentrations in Ambient Air

    EPA Science Inventory

    The current Federal Reference Method (FRM) for measuring concentrations of ozone in ambient air is based on the dry, gas-phase, chemiluminescence reaction between ethylene (C2H4) and any ozone (O3) that may be p...

  18. Ozone concentrations and damage for realistic future European climate and air quality scenarios

    NASA Astrophysics Data System (ADS)

    Hendriks, Carlijn; Forsell, Nicklas; Kiesewetter, Gregor; Schaap, Martijn; Schöpp, Wolfgang

    2016-11-01

    Ground level ozone poses a significant threat to human health from air pollution in the European Union. While anthropogenic emissions of precursor substances (NOx, NMVOC, CH4) are regulated by EU air quality legislation and will decrease further in the future, the emissions of biogenic NMVOC (mainly isoprene) may increase significantly in the coming decades if short-rotation coppice plantations are expanded strongly to meet the increased biofuel demand resulting from the EU decarbonisation targets. This study investigates the competing effects of anticipated trends in land use change, anthropogenic ozone precursor emissions and climate change on European ground level ozone concentrations and related health and environmental impacts until 2050. The work is based on a consistent set of energy consumption scenarios that underlie current EU climate and air quality policy proposals: a current legislation case, and an ambitious decarbonisation case. The Greenhouse Gas-Air Pollution Interactions and Synergies (GAINS) integrated assessment model was used to calculate air pollutant emissions for these scenarios, while land use change because of bioenergy demand was calculated by the Global Biosphere Model (GLOBIOM). These datasets were fed into the chemistry transport model LOTOS-EUROS to calculate the impact on ground level ozone concentrations. Health damage because of high ground level ozone concentrations is projected to decline significantly towards 2030 and 2050 under current climate conditions for both energy scenarios. Damage to plants is also expected to decrease but to a smaller extent. The projected change in anthropogenic ozone precursor emissions is found to have a larger impact on ozone damage than land use change. The increasing effect of a warming climate (+2-5 °C across Europe in summer) on ozone concentrations and associated health damage, however, might be higher than the reduction achieved by cutting back European ozone precursor emissions. Global

  19. Implications of limiting CO2 concentrations for land use and energy.

    PubMed

    Wise, Marshall; Calvin, Katherine; Thomson, Allison; Clarke, Leon; Bond-Lamberty, Benjamin; Sands, Ronald; Smith, Steven J; Janetos, Anthony; Edmonds, James

    2009-05-29

    Limiting atmospheric carbon dioxide (CO2) concentrations to low levels requires strategies to manage anthropogenic carbon emissions from terrestrial systems as well as fossil fuel and industrial sources. We explore the implications of fully integrating terrestrial systems and the energy system into a comprehensive mitigation regime that limits atmospheric CO2 concentrations. We find that this comprehensive approach lowers the cost of meeting environmental goals but also carries with it profound implications for agriculture: Unmanaged ecosystems and forests expand, and food crop and livestock prices rise. Finally, we find that future improvement in food crop productivity directly affects land-use change emissions, making the technology for growing crops potentially important for limiting atmospheric CO2 concentrations.

  20. Autism spectrum disorder prevalence and associations with air concentrations of lead, mercury, and arsenic.

    PubMed

    Dickerson, Aisha S; Rahbar, Mohammad H; Bakian, Amanda V; Bilder, Deborah A; Harrington, Rebecca A; Pettygrove, Sydney; Kirby, Russell S; Durkin, Maureen S; Han, Inkyu; Moyé, Lemuel A; Pearson, Deborah A; Wingate, Martha Slay; Zahorodny, Walter M

    2016-07-01

    Lead, mercury, and arsenic are neurotoxicants with known effects on neurodevelopment. Autism spectrum disorder (ASD) is a neurodevelopmental disorder apparent by early childhood. Using data on 4486 children with ASD residing in 2489 census tracts in five sites of the Centers for Disease Control and Prevention's Autism and Developmental Disabilities Monitoring (ADDM) Network, we used multi-level negative binomial models to investigate if ambient lead, mercury, and arsenic concentrations, as measured by the US Environmental Protection Agency National-Scale Air Toxics Assessment (EPA-NATA), were associated with ASD prevalence. In unadjusted analyses, ambient metal concentrations were negatively associated with ASD prevalence. After adjusting for confounding factors, tracts with air concentrations of lead in the highest quartile had significantly higher ASD prevalence than tracts with lead concentrations in the lowest quartile (prevalence ratio (PR) = 1.36; 95 '% CI: 1.18, 1.57). In addition, tracts with mercury concentrations above the 75th percentile (>1.7 ng/m(3)) and arsenic concentrations below the 75th percentile (≤0.13 ng/m(3)) had a significantly higher ASD prevalence (adjusted RR = 1.20; 95 % CI: 1.03, 1.40) compared to tracts with arsenic, lead, and mercury concentrations below the 75th percentile. Our results suggest a possible association between ambient lead concentrations and ASD prevalence and demonstrate that exposure to multiple metals may have synergistic effects on ASD prevalence.

  1. Total internal reflection-based planar waveguide solar concentrator with symmetric air prisms as couplers.

    PubMed

    Xie, Peng; Lin, Huichuan; Liu, Yong; Li, Baojun

    2014-10-20

    We present a waveguide coupling approach for planar waveguide solar concentrator. In this approach, total internal reflection (TIR)-based symmetric air prisms are used as couplers to increase the coupler reflectivity and to maximize the optical efficiency. The proposed concentrator consists of a line focusing cylindrical lens array over a planar waveguide. The TIR-based couplers are located at the focal line of each lens to couple the focused sunlight into the waveguide. The optical system was modeled and simulated with a commercial ray tracing software (Zemax). Results show that the system used with optimized TIR-based couplers can achieve 70% optical efficiency at 50 × geometrical concentration ratio, resulting in a flux concentration ratio of 35 without additional secondary concentrator. An acceptance angle of ± 7.5° is achieved in the x-z plane due to the use of cylindrical lens array as the primary concentrator.

  2. Limiting concentrations of activated mononucleotides necessary for poly(C)-directed elongation of oligoguanylates

    NASA Technical Reports Server (NTRS)

    Kanavarioti, A.; Chang, S.; Alberas, D. J.

    1990-01-01

    Selected imidazolide-activated nucleotides have been subjected to hydrolysis under conditions similar to those that favor their template-directed oligomerization. Rate constants of hydrolysis of the P-N bond in guanosine 5'-monophosphate 2-methylimidazolide (2-MeImpG) and in guanosine 5'-monophosphate imidazolide (ImpG), kh, have been determined in the presence/absence of magnesium ion as a function of temperature and polycytidylate [poly(C)] concentration. Using the rate constant of hydrolysis of 2-MeImpG and the rate constant of elongation, i.e., the reaction of an oligoguanylate with 2-MeImpG in the presence of poly(C) acting as template, the limiting concentration of 2-MeImpG necessary for oligonucleotide elongation to compete with hydrolysis can be calculated. The limiting concentration is defined as the initial concentration of monomer that results in its equal consumption by hydrolysis and by elongation. These limiting concentrations of 2-MeImpG are found to be 1.7 mM at 37 degrees C and 0.36 mM at 1 degrees C. Boundary conditions in the form of limiting concentration of activated nucleotide may be used to evaluate a prebiotic model for chemical synthesis of biopolymers. For instance, the limiting concentration of monomer can be used as a basis of comparison among catalytic, but nonenzymatic, RNA-type systems. We also determined the rate constant of dimerization of 2-MeImpG, k2 = 0.45 +/- 0.06 M-1 h-1 in the absence of poly(C), and 0.45 +/- 0.06 less than or equal to k2 less than or equal to 0.97 +/- 0.13 M-1 h-1 in its presence at 37 degrees C and pH 7.95.(ABSTRACT TRUNCATED AT 250 WORDS).

  3. Deposition and air concentrations of permethrin and naled used for adult mosquito management.

    PubMed

    Schleier, Jerome J; Peterson, Robert K D

    2010-01-01

    One of the most effective ways of managing adult mosquitoes that vector human and animal pathogens is the use of ultra-low-volume (ULV) insecticides. Because of the lack of environmental fate studies and concerns about the safety of the insecticides used for the management of adult mosquitoes, we conducted an environmental fate study after truck-mounted applications of permethrin and naled. One hour after application, concentrations of permethrin on cotton dosimeters placed at ground level 25, 50, and 75 m from the spray source were 2, 4, and 1 ng/cm2 in 2007 and 5, 2, and 0.9 ng/cm2 in 2008, respectively. One hour after application, concentrations of naled 25, 50, and 75 m were 47, 66, and 67 ng/cm2 in 2007 and 15, 6.1, and 0 (nondetectable) ng/cm2 in 2008, respectively. Deposition concentrations 12 h after application were not significantly different than 1 h after application for permethrin and naled either year. During 2007 and 2008 permethrin applications, two quantifiable air concentrations of 375 and 397 ng/m3 were observed 1 h after application. In 2007 and 2008, naled air concentrations ranged from 2300 to 4000 ng/m3 1 h after application. There were no quantifiable air concentrations between 1 and 12 h after application in either 2007 or 2008 for both naled and permethrin. Environmental concentrations observed in this study demonstrate that models used in previous risk assessments were sufficiently conservative (i.e., the models overestimated environmental concentrations). However, we also demonstrate inadequacies of models such as AgDrift and AGDISP, which currently are used by the US Environmental Protection Agency to estimate environmental concentrations of ULV insecticides. PMID:19536586

  4. Soil air carbon dioxide and nitrous oxide concentrations in profiles under tallgrass prairie and cultivation

    SciTech Connect

    Sotomayor, D.; Rice, C.W.

    1999-05-01

    Assessing the dynamics of gaseous production in soils is of interest because they are important sources and sinks of greenhouse gases. Changes in soil air carbon dioxide (CO{sub 2}) and nitrous oxide (N{sub 2}O) concentrations were studied in a Reading silt loam under prairie and cultivation. Concentrations were measured in situ over a 17-mo period to a depth of 3 m. Multilevel samples permitted collection of gases with subsequent measurement by gas chromatography in the laboratory. Soil air N{sub 2}O concentrations were near atmospheric levels for a majority of the study period in the prairie site but were significantly higher in the cultivated site. Annual mean N{sub 2}O concentrations were 0.403 and 1.09 {micro}L L{sup {minus}1} in the prairie and cultivated sites, respectively. Soil air CO{sub 2} annual mean concentrations were 1.56 {times} 10{sup 4} and 1.10 {times} 10{sup 4} {micro}L L{sup {minus}1} and ranged from 0.096 {times} 10{sup 4} to 6.45 {times} 10{sup 4} {micro}L L{sup {minus}1} and 0.087 {times} 10{sup 4} to 3.59 {times} 10{sup 4} {micro}L L{sup {minus}1} in the prairie and cultivated sites, respectively. Concentrations generally increased with depth, with maximum soil air N{sub 2}O and CO{sub 2} concentrations at 1.0 m in the prairie site and 0.5 m in the cultivated site. Nitrous oxide in the cultivated site and CO{sub 2} at both sites did not change markedly over winter months, but CO{sub 2} and N{sub 2}O concentrations reached maximums during the summer months and decreased as the year progressed. Although soil air concentrations peaked and decreased faster at shallower depths, deeper depths exhibited relative maximum concentrations for longer time periods.

  5. Radiation extinction limit of counterflow premixed lean methane-air flames

    SciTech Connect

    Guo, H.; Ju, Y.; Maruta, Kaoru; Niioka, Takashi; Liu, F.

    1997-06-01

    The application of the laminar flamelet concept to turbulent flame modeling requires a detailed understanding of stretched laminar flames. In this study, the authors used numerical methods, including arc-length continuation, to simulate the extinction characteristics of counterflow premixed fuel-lean, methane-air flames. Attention was primarily paid to the effect of radiative heat loss on the extinction characteristics of these flames. The results show that at medium to low values of the stretch rate, the radiative heat loss has a particularly strong impact on the counterflow premixed fuel-lean, methane-air flames. It was also found that, in addition to the stretch extinction limit at a high stretch rate, there exists a radiation extinction limit at a low stretch rate. Furthermore, the relationship between these two extinction limits and the equivalence ratio is obtained.

  6. Extinction of Lean Near-Limit Methane/Air Flames at Elevated Pressures under Normal- and Micro-Gravity

    SciTech Connect

    Zhang, H.; Fan, R.; Wang, S.; Tian, X.; Xu, K.; Wan, S.; Egolfopoulos, Fokion N.

    2011-01-01

    The extinction limits of lean, near-limit, counterflowing, CH{sub 4}/air twin premixed flames were studied experimentally at evaluated pressures and under normal- and micro-gravity conditions utilizing the 3.5 s drop tower of the National Microgravity Laboratory of China. The results showed that under micro-gravity conditions the natural convection is minimized and the flames become more planar and symmetric compared to normal gravity. In both normal- and micro-gravity experiments and for a given strain rate and fuel concentration, the flame luminosity was found to enhance as the pressure increases. On the other hand, at a given pressure, the flame luminosity was determined to weaken as the strain rate decreases. At a given strain rate, the fuel concentration at extinction was found to vary non-monotonically with pressure, namely it first increases and subsequently decreases with pressure. The limit fuel concentration peaks around 3 and 4 atm under normal- and micro-gravity, respectively. The extinction limits measured at micro-gravity were in good agreement with predictions obtained through detailed numerical simulations but they are notably lower compared to the data obtained under normal gravity. The simulations confirmed the non-monotonic variation of flammability limits with pressure, in agreement with previous studies. Sensitivity analysis showed that for pressures between one and 5 atm, the near-limit flame response is dominated by the competition between the main branching, H + O{sub 2} → OH + O, and the pressure sensitive termination, H + O{sub 2} + M → HO{sub 2} + M, reaction. However, for pressures greater than 5 atm it was determined that the HO{sub 2} kinetics result in further chain branching in a way that is analogous to the third explosion limit of H{sub 2}/O{sub 2} mixtures.

  7. Ozone concentration in leaf intercellular air spaces is close to zero

    SciTech Connect

    Laisk, A.; Moldau, H. ); Kull, O. )

    1989-07-01

    Transpiration and ozone uptake rates were measured simultaneously in sunflower leaves at different stomatal openings and various ozone concentrations. Ozone uptake rates were proportional to the ozone concentration up to 1500 nanoliters per liter. The leaf gas phase diffusion resistance (stomatal plus boundary layer) to water vapor was calculated and converted to the resistance to ozone multiplying it by the theoretical ratio of diffusion coefficients for water vapor and ozone in air (1.67). The ozone concentration in intercellular air spaces calculated from the ozone uptake rate and diffusion resistance to ozone scattered around zero. The ozone concentration in intercellular air spaces was measured directly bu supplying ozone to the leaf from one side and measuring the equilibrium concentration above the other side, and it was found to be zero. The total leaf resistance to ozone was proportional to the gas phase resistance to water vapor with a coefficient of 1.68. It is concluded that ozone enters the leaf by diffusion through the stomata, and is rapidly decomposed in cell walls and plasmalemma.

  8. Ozone concentration in leaf intercellular air spaces is close to zero.

    PubMed

    Laisk, A; Kull, O; Moldau, H

    1989-07-01

    Transpiration and ozone uptake rates were measured simultaneously in sunflower leaves at different stomatal openings and various ozone concentrations. Ozone uptake rates were proportional to the ozone concentration up to 1500 nanoliters per liter. The leaf gas phase diffusion resistance (stomatal plus boundary layer) to water vapor was calculated and converted to the resistance to ozone multiplying it by the theoretical ratio of diffusion coefficients for water vapor and ozone in air (1.67). The ozone concentration in intercellular air spaces calculated from the ozone uptake rate and diffusion resistance to ozone scattered around zero. The ozone concentration in intercellular air spaces was measured directly by supplying ozone to the leaf from one side and measuring the equilibrium concentration above the other side, and it was found to be zero. The total leaf resistance to ozone was proportional to the gas phase resistance to water vapor with a coefficient of 1.68. It is concluded that ozone enters the leaf by diffusion through the stomata, and is rapidly decomposed in cell walls and plasmalemma.

  9. Study of a cave's air exchange pattern based on radon concentration and the time dependence of radon concentration in Pál-völgy Cave (Budapest, Hungary)

    NASA Astrophysics Data System (ADS)

    Nagy, H. E.; Horvath, A.; Jordan, Gy.; Szabo, Cs.; Kiss, A.

    2012-04-01

    A long-term (one year and a half), high resolution, with an integration time of one hour, radon concentration monitoring was carried out in Pál-völgy Cave (Budapest, Hungary). Our major goal was to determine the time dependence of radon concentration in the cave and to understand the exchange pattern of the cave air with the outdoor air based on radon concentrations, and to determine the factors that affect the radon concentration in the cave air. Pál-völgy Cave is situated in the Buda Hills, which is the NE part of the Transdanubian Central Range. The wall rock of the cave is dominantly Eocene Szépvölgy Limestone Formation. Above the limestone Eocene Buda Marl and Oligocene Tard Clay are deposited. A huge multiphase hydrothermal cave system developed in the Szépvölgy Limestone and partially in the Buda Marl resulted in a long-term complex paleokarstic evolution from the Late Eocene to the Quaternary. The radon concentration in the cave air was measured continuously by an AlphaGuard radon monitor, and meteorological parameters outside the cave were also collected simultaneously. The arithmetic mean of the annual radon concentration was 1.9 kBq/m3 and the radon concentration varied between 104-7,776 Bq/m3. In addition, the results indicate a clear seasonal variability of radon concentration in the cave air: in winter the radon concentration fluctuates around a low mean value of 253 Bq/m3, in summer it oscillates around a high mean value of 5,504 Bq/m3, whereas in spring and autumn the radon level varies between the winter and summer values. The summer to winter radon concentration ratio (radon concentration in summer/radon concentration in winter) was high, 21.8. The outside air temperature showed the strongest correlation with the radon concentration in the cave, Pierson's linear correlation coefficient is 0.76. If the outdoor air temperature is lower than the cave air temperature (12 °C), especially in autumn and winter the air flows from outside into the

  10. Chlorinated paraffins in indoor air and dust: concentrations, congener patterns, and human exposure.

    PubMed

    Fridén, Ulrika E; McLachlan, Michael S; Berger, Urs

    2011-10-01

    Chlorinated paraffins (CPs) are large production volume chemicals used in a wide variety of commercial applications. They are ubiquitous in the environment and humans. Human exposure via the indoor environment has, however, been barely investigated. In the present study 44 indoor air and six dust samples from apartments in Stockholm, Sweden, were analyzed for CPs, and indoor air concentrations are reported for the first time. The sumCP concentration (short chain CPs (SCCPs) and medium chain CPs (MCCPs)) in air ranged from <5-210 ng m(-3) as quantified by gas chromatography coupled to electron ionization tandem mass spectrometry (GC/EI-MS/MS). Congener group patterns were studied using GC with electron capture negative ionization MS (GC/ECNI-MS). The air samples were dominated by the more volatile SCCPs compared to MCCPs. SumCPs were quantified by GC/EI-MS/MS in the dust samples at low μg g(-1) levels, with a chromatographic pattern suggesting the prevalence of longer chain CPs compared to air. The median exposure to sumCPs via the indoor environment was estimated to be ~1 μg day(-1) for both adults and toddlers. Adult exposure was dominated by inhalation, while dust ingestion was suggested to be more important for toddlers. Comparing these results to literature data on dietary intake indicates that human exposure to CPs from the indoor environment is not negligible. PMID:21612825

  11. Fungal spore concentrations in two haematopoietic stem cell transplantation (HSCT) units containing distinct air control systems.

    PubMed

    Brun, C P; Miron, D; Silla, L M R; Pasqualotto, A C

    2013-04-01

    Invasive fungal diseases have emerged as important causes of morbidity and mortality in haematological patients. In this study air samples were collected in two haematopoietic stem cell transplantation (HSCT) units, in which distinct air-control systems were in place. In hospital 1 no high-efficiency particulate air (HEPA) filter was available whereas in hospital 2 HSCT rooms were equipped with HEPA filters, with positive air pressure in relation to the corridor. A total of 117 samples from rooms, toilets and corridors were obtained during December 2009 to January 2011, using a six-stage Andersen sampler. In both hospitals, the concentration of potentially pathogenic fungi in the air was reduced in patients' rooms compared to corridors (P < 0·0001). Despite the presence of a HEPA filter in hospital 2, rooms in both hospitals showed similar concentrations of potentially pathogenic fungi (P = 0·714). These findings may be explained by the implementation of additional protective measures in hospital 1, emphasizing the importance of such measures in protected environments. PMID:22691688

  12. Investigation of air pollution concentration in Kathmandu valley during winter season.

    PubMed

    Kondo, Akir; Kaga, Akikazu; Imamura, Kiyoshi; Inoue, Yoshio; Sugisawa, Masahiko; Shrestha, Manohar Lal; Sapkota, Balkrishan

    2005-01-01

    The monthly concentrations of NO2, NOx, SO2 and O3 measured by a passive sampler from February 2003 to January 2004 showed that the air pollution during the winter season in Kathmandu valley was higher than the summer season. The O3 level was found the highest during April, May and June due to strong radiation. The hourly concentrations of NO2, NOx, O3 and suspended particulate matter (SPM) were also measured by automatic instruments on December 2003. Temperature at the height of 60 m and 400 m at Raniban Mountain in the northwest of Kathmandu valley was measured on February 2001 in the winter season and the average potential temperature gradient was estimated from observed temperature. Wind speed was also measured at the department of hydrology, airport section, from 18 February to 6 March 2001. It was found that the stable layer and the calm condition in the atmosphere strongly affected the appearance of the maximum concentrations of NO2 and SPM in the morning, and that the unstable layer and the windy condition in the atmosphere was considerably relevant to the decrease of air pollution concentrations at daytime. The emission amounts of NOx, HCs and total suspended particle(TSP) from transport sector in 2003 were estimated from the increasing rate of vehicles on the basis of the emission amounts in 1993 to be 3751 t/a, 30570 t/a and 1317 t/a, respectively. The diurnal concentrations in 2003 calculated by the two-layers box model reproduced the characteristics of air pollution in Kathmandu valley such as the maximum value of O3 and its time, the maximum value of NO in the morning, and the decrease of NO and NO2 at daytime. The comparison with the concentrations in 1993 calculated suggested that the main cause of air pollution was the emission from transport sector.

  13. Air toxics concentrations, source identification, and health risks: An air pollution hot spot in southwest Memphis, TN

    NASA Astrophysics Data System (ADS)

    Jia, Chunrong; Foran, Jeffery

    2013-12-01

    Southwest Memphis is a residential region surrounded by fossil fuel burning, steel, refining, and food processing industries, and considerable mobile sources whose emissions may pose adverse health risks to local residents. This study characterizes cancer and non-cancer risks resulting from exposure to ambient air toxics in southwest Memphis. Air toxics samples were collected at a central location every 6 days from June 5, 2008 to January 8, 2010. Volatile organic compounds (VOCs) were collected in evacuated stainless-steel canisters and aldehydes by DNPH cartridges, and samples were analyzed for 73 target compounds. A total of 60 compounds were detected and 39 were found in over 86% of the samples. Mean concentrations of many compounds were higher than those measured in many industrial communities throughout the U.S. The cumulative cancer risk associated with exposure to 13 carcinogens found in southwest Memphis air was 2.3 × 10-4, four times higher than the national average of 5.0 × 10-5. Three risk drivers were identified: benzene, formaldehyde, and acrylonitrile, which contributed 43%, 19%, and 14% to the cumulative risk, respectively. This is the first field study to confirm acrylonitrile as a potential risk driver. Mobile, secondary, industrial, and background sources contributed 57%, 24%, 14%, and 5% of the risk, respectively. The results of this study indicate that southwest Memphis, a region of significant income, racial, and social disparities, is also a region under significant environmental stress compared with surrounding areas and communities.

  14. Biomimetic air sampling for detection of low concentrations of molecules and bioagents : LDRD 52744 final report.

    SciTech Connect

    Hughes, Robert Clark

    2003-12-01

    Present methods of air sampling for low concentrations of chemicals like explosives and bioagents involve noisy and power hungry collectors with mechanical parts for moving large volumes of air. However there are biological systems that are capable of detecting very low concentrations of molecules with no mechanical moving parts. An example is the silkworm moth antenna which is a highly branched structure where each of 100 branches contains about 200 sensory 'hairs' which have dimensions of 2 microns wide by 100 microns long. The hairs contain about 3000 pores which is where the gas phase molecules enter the aqueous (lymph) phase for detection. Simulations of diffusion of molecules indicate that this 'forest' of hairs is 'designed' to maximize the extraction of the vapor phase molecules. Since typical molecules lose about 4 decades in diffusion constant upon entering the liquid phase, it is important to allow air diffusion to bring the molecule as close to the 'sensor' as possible. The moth acts on concentrations as low as 1000 molecules per cubic cm. (one part in 1e16). A 3-D collection system of these dimensions could be fabricated by micromachining techniques available at Sandia. This LDRD addresses the issues involved with extracting molecules from air onto micromachined structures and then delivering those molecules to microsensors for detection.

  15. Air conditioning impact on the dynamics of radon and its daughters concentration.

    PubMed

    Kozak, Krzysztof; Grządziel, Dominik; Połednik, Bernard; Mazur, Jadwiga; Dudzińska, Marzenna R; Mroczek, Mariusz

    2014-12-01

    Radon and its decay products are harmful pollutants present in indoor air and are responsible for the majority of the effective dose due to ionising radiation that people are naturally exposed to. The paper presents the results of the series of measurements of radon and its progeny (in unattached and attached fractions) as well as indoor air parameters: temperature, relative humidity, number and mass concentrations of fine aerosol particles. The measurements were carried out in the auditorium (lecture hall), which is an indoor air quality laboratory, in controlled conditions during two periods of time: when air conditioning (AC) was switched off (unoccupied auditorium) and when it was switched on (auditorium in normal use). The significant influence of AC and of students' presence on the dynamics of radon and its progeny was confirmed. A decrease in the mean value of radon and its attached progeny was found when AC was working. The mean value of radon equilibrium factor F was also lower when AC was working (0.49) than when it was off (0.61). The linear correlations were found between attached radon progeny concentration and particle number and mass concentration only when the AC was switched off. This research is being conducted with the aim to study the variability of radon equilibrium factor F which is essential to determine the effective dose due to radon and its progeny inhalation.

  16. Air conditioning impact on the dynamics of radon and its daughters concentration.

    PubMed

    Kozak, Krzysztof; Grządziel, Dominik; Połednik, Bernard; Mazur, Jadwiga; Dudzińska, Marzenna R; Mroczek, Mariusz

    2014-12-01

    Radon and its decay products are harmful pollutants present in indoor air and are responsible for the majority of the effective dose due to ionising radiation that people are naturally exposed to. The paper presents the results of the series of measurements of radon and its progeny (in unattached and attached fractions) as well as indoor air parameters: temperature, relative humidity, number and mass concentrations of fine aerosol particles. The measurements were carried out in the auditorium (lecture hall), which is an indoor air quality laboratory, in controlled conditions during two periods of time: when air conditioning (AC) was switched off (unoccupied auditorium) and when it was switched on (auditorium in normal use). The significant influence of AC and of students' presence on the dynamics of radon and its progeny was confirmed. A decrease in the mean value of radon and its attached progeny was found when AC was working. The mean value of radon equilibrium factor F was also lower when AC was working (0.49) than when it was off (0.61). The linear correlations were found between attached radon progeny concentration and particle number and mass concentration only when the AC was switched off. This research is being conducted with the aim to study the variability of radon equilibrium factor F which is essential to determine the effective dose due to radon and its progeny inhalation. PMID:24375376

  17. The Impact of Future Emissions Changes on Air Pollution Concentrations and Related Human Health Effects

    NASA Astrophysics Data System (ADS)

    Mikolajczyk, U.; Suppan, P.; Williams, M.

    2015-12-01

    Quantification of potential health benefits of reductions in air pollution on the local scale is becoming increasingly important. The aim of this study is to conduct health impact assessment (HIA) by utilizing regionally and spatially specific data in order to assess the influence of future emission scenarios on human health. In the first stage of this investigation, a modeling study was carried out using the Weather Research and Forecasting (WRF) model coupled with Chemistry to estimate ambient concentrations of air pollutants for the baseline year 2009, and for the future emission scenarios in southern Germany. Anthropogenic emissions for the baseline year 2009 are derived from the emission inventory provided by the Netherlands Organization of Applied Scientific Research (TNO) (Denier van der Gon et al., 2010). For Germany, the TNO emissions were replaced by gridded emission data with a high spatial resolution of 1/64 x 1/64 degrees. Future air quality simulations are carried out under different emission scenarios, which reflect possible energy and climate measures in year 2030. The model set-up included a nesting approach, where three domains with horizontal resolution of 18 km, 6 km and 2 km were defined. The simulation results for the baseline year 2009 are used to quantify present-day health burdens. Concentration-response functions (CRFs) for PM2.5 and NO2 from the WHO Health risks of air Pollution in Europe (HRAPIE) project were applied to population-weighted mean concentrations to estimate relative risks and hence to determine numbers of attributable deaths and associated life-years lost. In the next step, future health impacts of projected concentrations were calculated taking into account different emissions scenarios. The health benefits that we assume with air pollution reductions can be used to provide options for future policy decisions to protect public health.

  18. Occupational dimethylformamide exposure. 1. Diffusive sampling of dimethylformamide vapor for determination of time-weighted average concentration in air.

    PubMed

    Yasugi, T; Kawai, T; Mizunuma, K; Horiguchi, S; Iguchi, H; Ikeda, M

    1992-01-01

    A diffusive sampling method with water as absorbent was examined in comparison with 3 conventional methods of diffusive sampling with carbon cloth as absorbent, pumping through National Institute of Occupational Safety and Health (NIOSH) charcoal tubes, and pumping through NIOSH silica gel tubes to measure time-weighted average concentration of dimethylformamide (DMF). DMF vapors of constant concentrations at 3-110 ppm were generated by bubbling air at constant velocities through liquid DMF followed by dilution with fresh air. Both types of diffusive samplers could either absorb or adsorb DMF in proportion to time (0.25-8 h) and concentration (3-58 ppm), except that the DMF adsorbed was below the measurable amount when carbon cloth samplers were exposed at 3 ppm for less than 1 h. When both diffusive samplers were loaded with DMF and kept in fresh air, the DMF in water samplers stayed unchanged for at least for 12 h. The DMF in carbon cloth samplers showed a decay with a half-time of 14.3 h. When the carbon cloth was taken out immediately after termination of DMF exposure, wrapped in aluminum foil, and kept refrigerated, however, there was no measurable decrease in DMF for at least 3 weeks. When the air was drawn at 0.2 l/min, a breakthrough of the silica gel tube took place at about 4,000 ppm.min (as the lower 95% confidence limit), whereas charcoal tubes could tolerate even heavier exposures, suggesting that both tubes are fit to measure the 8-h time-weighted average of DMF at 10 ppm. PMID:1577523

  19. Detonation propagation in hydrogen-air mixtures with transverse concentration gradients

    NASA Astrophysics Data System (ADS)

    Boeck, L. R.; Berger, F. M.; Hasslberger, J.; Sattelmayer, T.

    2016-03-01

    The influence of transverse concentration gradients on detonation propagation in H_2-air mixtures is investigated experimentally in a wide parameter range. Detonation fronts are characterized by means of high-speed shadowgraphy, OH* imaging, pressure measurements, and soot foils. Steep concentration gradients at low average H_2 concentrations lead to single-headed detonations. A maximum velocity deficit compared to the Chapman-Jouguet velocity of 9 % is observed. Significant amounts of mixture seem to be consumed by turbulent deflagration behind the leading detonation. Wall pressure measurements show high local pressure peaks due to strong transverse waves caused by the concentration gradients. Higher average H_2 concentrations or weaker gradients allow for multi-headed detonation propagation.

  20. Concentrations of antibiotics predicted to select for resistant bacteria: Proposed limits for environmental regulation.

    PubMed

    Bengtsson-Palme, Johan; Larsson, D G Joakim

    2016-01-01

    There are concerns that selection pressure from antibiotics in the environment may accelerate the evolution and dissemination of antibiotic-resistant pathogens. Nevertheless, there is currently no regulatory system that takes such risks into account. In part, this is due to limited knowledge of environmental concentrations that might exert selection for resistant bacteria. To experimentally determine minimal selective concentrations in complex microbial ecosystems for all antibiotics would involve considerable effort. In this work, our aim was to estimate upper boundaries for selective concentrations for all common antibiotics, based on the assumption that selective concentrations a priori need to be lower than those completely inhibiting growth. Data on Minimal Inhibitory Concentrations (MICs) were obtained for 111 antibiotics from the public EUCAST database. The 1% lowest observed MICs were identified, and to compensate for limited species coverage, predicted lowest MICs adjusted for the number of tested species were extrapolated through modeling. Predicted No Effect Concentrations (PNECs) for resistance selection were then assessed using an assessment factor of 10 to account for differences between MICs and minimal selective concentrations. The resulting PNECs ranged from 8 ng/L to 64 μg/L. Furthermore, the link between taxonomic similarity between species and lowest MIC was weak. This work provides estimated upper boundaries for selective concentrations (lowest MICs) and PNECs for resistance selection for all common antibiotics. In most cases, PNECs for selection of resistance were below available PNECs for ecotoxicological effects. The generated PNECs can guide implementation of compound-specific emission limits that take into account risks for resistance promotion.

  1. Concentrations and patterns of polychlorinated naphthalenes in urban air in Beijing, China.

    PubMed

    Xue, Lingnan; Zhang, Lifei; Yan, Yan; Dong, Liang; Huang, Yeru; Li, Xiaoxiu

    2016-11-01

    Air samples were collected, using a high-volume air sampler, at an urban site in Beijing from April 2014 to March 2015. The polychlorinated naphthalene (PCN) concentration in the atmosphere in each season was determined. The total PCN (total target tri- to octachloronaphthalene congeners) concentrations were 1.99-19.0 pg/m(3), and the mean was 7.20 pg/m(3). The PCN concentrations were higher in fall than summer, indicating that the concentrations varied significantly over time. The trichloronaphthalene homolog was the predominant PCN homolog in all four seasons. The PCN toxic equivalent (TEQ) concentrations were 0.42-6.89 fg/m(3), and the mean was 1.74 fg/m(3). The CN-66/67 and CN-73 congeners were the predominant contributors to the TEQ concentrations. The mean seasonal TEQ concentration decreased in the order fall (3.18 fg/m(3)) > winter (1.41 fg/m(3)) > summer (1.11 fg/m(3)) > spring (1.03 fg/m(3)). The TEQ concentrations and the PCN concentrations did not follow the same seasonal trends, but the highest TEQ and PCN concentrations were both found in fall. Correlation analysis, ratio analysis, and principal component analysis were used to investigate the sources of PCNs to the Beijing atmosphere. The results suggested that combustion processes may be the main sources of PCNs to the Beijing atmosphere.

  2. Concentrations and patterns of polychlorinated naphthalenes in urban air in Beijing, China.

    PubMed

    Xue, Lingnan; Zhang, Lifei; Yan, Yan; Dong, Liang; Huang, Yeru; Li, Xiaoxiu

    2016-11-01

    Air samples were collected, using a high-volume air sampler, at an urban site in Beijing from April 2014 to March 2015. The polychlorinated naphthalene (PCN) concentration in the atmosphere in each season was determined. The total PCN (total target tri- to octachloronaphthalene congeners) concentrations were 1.99-19.0 pg/m(3), and the mean was 7.20 pg/m(3). The PCN concentrations were higher in fall than summer, indicating that the concentrations varied significantly over time. The trichloronaphthalene homolog was the predominant PCN homolog in all four seasons. The PCN toxic equivalent (TEQ) concentrations were 0.42-6.89 fg/m(3), and the mean was 1.74 fg/m(3). The CN-66/67 and CN-73 congeners were the predominant contributors to the TEQ concentrations. The mean seasonal TEQ concentration decreased in the order fall (3.18 fg/m(3)) > winter (1.41 fg/m(3)) > summer (1.11 fg/m(3)) > spring (1.03 fg/m(3)). The TEQ concentrations and the PCN concentrations did not follow the same seasonal trends, but the highest TEQ and PCN concentrations were both found in fall. Correlation analysis, ratio analysis, and principal component analysis were used to investigate the sources of PCNs to the Beijing atmosphere. The results suggested that combustion processes may be the main sources of PCNs to the Beijing atmosphere. PMID:27497350

  3. Seasonal change of persistent organic pollutant concentrations in air at Niigata area, Japan.

    PubMed

    Murayama, Hitoshi; Takase, Yuuya; Mitobe, Hideko; Mukai, Hiroyuki; Ohzeki, Toshiharu; Shimizu, Ken-ichi; Kitayama, Yoshie

    2003-07-01

    The concentrations of persistent organic pollutants (POPs), such as HCB, alpha-, beta-, gamma- and delta-HCH, trans- and cis-chlordane (t-CHL, c-CHL), DDE, DDD and DDT, in ambient air have been measured at five sampling points in Niigata area, Japan (Niigata, Maki, Tsubame, Jouzo and Yahiko) during the period from September 1999 to November 2001. HCB, alpha-HCH, t-CHL and c-CHL showed higher concentrations than the other chemicals in all locations. All the POPs except t-CHL and c-CHL collected at urban sites of the Niigata Plain was almost the same in their concentration levels. Higher concentrations of t-CHL and c-CHL in residential areas should be attributed to the past usage of the chemical as a termiticide. At Yahiko (remote site), most of the POPs showed lower concentrations than those measured at the other sampling sites, although alpha-HCH and gamma-HCH were comparable with the concentrations found at the other sampling sites. All POPs except alpha-HCH and gamma-HCH tend to decrease 41-80% in their concentrations from 2000 to 2001. The lower POPs concentrations in winter and the higher POPs concentrations in summer at every sampling point can be partly explained by temperature differences. Applying the equation of the logarithm of the POP partial pressure in air versus reciprocal temperature (lnPa=m/T+b) to our data, linear relations were observed. HCB gave a poor linearity and the smallest slope, while beta-HCH, t-CHL and c-CHL gave good linearities and large slopes in the equation. The results suggest that HCB level is influenced by not only the emission from terrestrial sources but the global-scale background pollution. A peculiar observation is that beta-HCH concentration measured in our study showed large temperature dependence, indicating there could be a source of contamination in the surrounding areas. PMID:12738282

  4. Assessment of regional air quality by a concentration-dependent Pollution Permeation Index

    NASA Astrophysics Data System (ADS)

    Liang, Chun-Sheng; Liu, Huan; He, Ke-Bin; Ma, Yong-Liang

    2016-10-01

    Although air quality monitoring networks have been greatly improved, interpreting their expanding data in both simple and efficient ways remains challenging. Therefore, needed are new analytical methods. We developed such a method based on the comparison of pollutant concentrations between target and circum areas (circum comparison for short), and tested its applications by assessing the air pollution in Jing-Jin-Ji, Yangtze River Delta, Pearl River Delta and Cheng-Yu, China during 2015. We found the circum comparison can instantly judge whether a city is a pollution permeation donor or a pollution permeation receptor by a Pollution Permeation Index (PPI). Furthermore, a PPI-related estimated concentration (original concentration plus halved average concentration difference) can be used to identify some overestimations and underestimations. Besides, it can help explain pollution process (e.g., Beijing’s PM2.5 maybe largely promoted by non-local SO2) though not aiming at it. Moreover, it is applicable to any region, easy-to-handle, and able to boost more new analytical methods. These advantages, despite its disadvantages in considering the whole process jointly influenced by complex physical and chemical factors, demonstrate that the PPI based circum comparison can be efficiently used in assessing air pollution by yielding instructive results, without the absolute need for complex operations.

  5. Quantile regression of indoor air concentrations of volatile organic compounds (VOC).

    PubMed

    Schlink, Uwe; Thiem, Alexander; Kohajda, Tibor; Richter, Matthias; Strebel, Kathrin

    2010-08-15

    There are many factors determining the concentration of volatile organic compounds (VOCs) in indoor air. On the basis of 601 population-based measurements we develop an explicit exposure model that includes factors, such as renovation, furniture, flat size, smoking, and education level of the occupants. As a novel method for the evaluation of concentrations of indoor air pollutants we use quantile regression, which has the advantages of robustness against non-Gaussian distributions (and outliers) and can adjust for unbalanced frequencies of observations. The applied bi- and multivariate quantile regressions provide (1) the VOC burden that is representative for the population of Leipzig, Germany, and (2) an inter-comparison of the effects of the studied factors and their levels. As a result, we find strong evidence for factors of general impact on most VOC components, such as the season, flooring, the type of the room, and the size of the apartment. Other impact factors are very specific to the VOC components. For example, wooden flooring (parquet) and new furniture increase the concentration of terpenes as well as the modifying factors high education and sampling in the child's room. Smokers ventilate their flats in an extent that in general reduces the VOC concentrations, except for benzene (contained in tobacco smoke), which is still higher in smoking than in non-smoking flats. Very often dampness is associated with an increased VOC burden in indoor air. An investigation of mixtures emphasises a high burden of co-occurring terpenes in very small and very large apartments.

  6. Volatile organic compound concentrations in ambient air of Kaohsiung petroleum refinery in Taiwan

    NASA Astrophysics Data System (ADS)

    Lin, Tsai-Yin; Sree, Usha; Tseng, Sen-Hong; Chiu, Kong Hwa; Wu, Chien-Hou; Lo, Jiunn-Guang

    The air quality assessment for volatile organic compounds (VOC) was conducted in and around Chinese petroleum corporation (CPC) refinery at Kaohsiung, located in southern Taiwan, during 2001 by collecting air samples at 26 sites. Benzene and toluene were detected as the most abundant VOC by both gas chromatography and ultra-violet differential optical absorption spectroscopy (UV-DOAS) techniques. BTXE concentrations showed day and night variations at some of the sampling site. The highest among the 26 sites for total concentration of VOC at CPC was 2506 ppbv near waste burning stack. High concentrations of VOC were also detected at the wastewater management area and the east gate of the plant. The values were 10-18 times higher than those probed in Kaohsiung city. The meteorological parameters such as wind speed and direction played vital roles in the distribution of ambient air VOC concentrations and affected the petrochemical complex emissions. The application of UV-DOAS for online monitoring of criteria pollutants appears feasible though the accuracy of the technique is not fully controlled.

  7. Assessment of regional air quality by a concentration-dependent Pollution Permeation Index

    PubMed Central

    Liang, Chun-Sheng; Liu, Huan; He, Ke-Bin; Ma, Yong-Liang

    2016-01-01

    Although air quality monitoring networks have been greatly improved, interpreting their expanding data in both simple and efficient ways remains challenging. Therefore, needed are new analytical methods. We developed such a method based on the comparison of pollutant concentrations between target and circum areas (circum comparison for short), and tested its applications by assessing the air pollution in Jing-Jin-Ji, Yangtze River Delta, Pearl River Delta and Cheng-Yu, China during 2015. We found the circum comparison can instantly judge whether a city is a pollution permeation donor or a pollution permeation receptor by a Pollution Permeation Index (PPI). Furthermore, a PPI-related estimated concentration (original concentration plus halved average concentration difference) can be used to identify some overestimations and underestimations. Besides, it can help explain pollution process (e.g., Beijing’s PM2.5 maybe largely promoted by non-local SO2) though not aiming at it. Moreover, it is applicable to any region, easy-to-handle, and able to boost more new analytical methods. These advantages, despite its disadvantages in considering the whole process jointly influenced by complex physical and chemical factors, demonstrate that the PPI based circum comparison can be efficiently used in assessing air pollution by yielding instructive results, without the absolute need for complex operations. PMID:27731344

  8. Ambient concentrations of aldehydes in relation to Beijing Olympic air pollution control measures

    NASA Astrophysics Data System (ADS)

    Gong, J. C.; Zhu, T.; Hu, M.; Zhang, L. W.; Cheng, H.; Zhang, L.; Tong, J.; Zhang, J.

    2010-08-01

    Aldehydes are ubiquitous constituents of the atmosphere. Their concentrations are elevated in polluted urban atmospheres. The present study was carried out to characterize three aldehydes of most health concern (formaldehyde, acetaldehyde, and acrolein) in a central Beijing site in the summer and early fall of 2008 (from June to October). Measurements were made before, during, and after the Beijing Olympics to examine whether the air pollution control measures implemented to improve Beijing's air quality during the Olympics had any impact on concentrations of the three aldehydes. Average concentrations of formaldehyde, acetaldehyde and acrolein were 29.34 ± 15.12 μg/m3, 27.09 ± 15.74 μg/m3 and 2.32 ± 0.95 μg/m3, respectively, for the entire period of measurements, all being the highest among the levels measured in cities around the world in photochemical smog seasons. Among the three measured aldehydes, only acetaldehyde had a substantially reduced mean concentration during the Olympic air pollution control period compared to the pre-Olympic period. Formaldehyde and acrolein followed the changing pattern of temperature and were each significantly correlated with ozone (a secondary product of photochemical reactions). In contrast, acetaldehyde was significantly correlated with several pollutants emitted mainly from local emission sources (e.g., NO2, CO, and PM2.5). These findings suggest that local direct emissions had a larger impact on acetaldehyde than formaldehyde and acrolein.

  9. Persistence analysis of extreme CO, NO2 and O3 concentrations in ambient air of Delhi

    NASA Astrophysics Data System (ADS)

    Chelani, Asha B.

    2012-05-01

    Persistence analysis of air pollutant concentration and corresponding exceedance time series is carried out to examine for temporal evolution. For this purpose, air pollutant concentrations, namely, CO, NO2 and O3 observed during 2000-2009 at a traffic site in Delhi are analyzed using detrended fluctuation analysis. Two types of extreme values are analyzed; exceeded concentrations to a threshold provided by national pollution controlling agency and time interval between two exceedances. The time series of three pollutants is observed to possess persistence property whereas the extreme value time series of only primary pollutant concentrations is found to be persistent. Two time scaling regions are observed to be significant in extreme time series of CO and NO2, mainly attributed to implementation of CNG in vehicles. The presence of persistence in three pollutant concentration time series is linked to the property of self-organized criticality. The observed persistence in the time interval between two exceeded levels is a matter of concern as persistent high concentrations can trigger health problems.

  10. 40 CFR 60.1445 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Air Curtain Incinerators That Burn 100 Percent Yard Waste § 60.1445 What are the emission limits for air curtain incinerators that burn 100 percent yard waste? If your air curtain incinerator combusts... curtain incinerators that burn 100 percent yard waste? 60.1445 Section 60.1445 Protection of...

  11. 40 CFR 60.1445 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... curtain incinerators that burn 100 percent yard waste? 60.1445 Section 60.1445 Protection of Environment... Air Curtain Incinerators That Burn 100 Percent Yard Waste § 60.1445 What are the emission limits for air curtain incinerators that burn 100 percent yard waste? If your air curtain incinerator...

  12. 40 CFR 62.14815 - What are the emission limitations for air curtain incinerators that burn 100 percent wood wastes...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... air curtain incinerators that burn 100 percent wood wastes, clean lumber and/or yard waste? 62.14815... Before November 30, 1999 Air Curtain Incinerators That Burn 100 Percent Wood Wastes, Clean Lumber And/or Yard Waste § 62.14815 What are the emission limitations for air curtain incinerators that burn...

  13. 40 CFR 60.1445 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... curtain incinerators that burn 100 percent yard waste? 60.1445 Section 60.1445 Protection of Environment... Air Curtain Incinerators That Burn 100 Percent Yard Waste § 60.1445 What are the emission limits for air curtain incinerators that burn 100 percent yard waste? If your air curtain incinerator...

  14. 40 CFR 60.1445 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... curtain incinerators that burn 100 percent yard waste? 60.1445 Section 60.1445 Protection of Environment... Air Curtain Incinerators That Burn 100 Percent Yard Waste § 60.1445 What are the emission limits for air curtain incinerators that burn 100 percent yard waste? If your air curtain incinerator...

  15. 40 CFR 60.1445 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... curtain incinerators that burn 100 percent yard waste? 60.1445 Section 60.1445 Protection of Environment... Air Curtain Incinerators That Burn 100 Percent Yard Waste § 60.1445 What are the emission limits for air curtain incinerators that burn 100 percent yard waste? If your air curtain incinerator...

  16. MODELING AIR TOXICS AND PM 2.5 CONCENTRATION FIELDS AS A MEANS FOR FACILITATING HUMAN EXPOSURE ASSESSMENTS

    EPA Science Inventory

    The capability of the US EPA Models-3/Community Multiscale Air Quality (CMAQ) modeling system is extended to provide gridded ambient air quality concentration fields at fine scales. These fields will drive human exposure to air toxics and fine particulate matter (PM2.5) models...

  17. How low can you go? Assessing minimum concentrations of NSC in carbon limited tree saplings

    NASA Astrophysics Data System (ADS)

    Hoch, Guenter; Hartmann, Henrik; Schwendener, Andrea

    2016-04-01

    Tissue concentrations of non-structural carbohydrates (NSC) are frequently used to determine the carbon balance of plants. Over the last years, an increasing number of studies have inferred carbon starvation in trees under environmental stress like drought from low tissue NSC concentrations. However, such inferences are limited by the fact that minimum concentrations of NSC required for survival are not known. So far, it was hypothesized that even under lethal carbon starvation, starch and low molecular sugar concentrations cannot be completely depleted and that minimum NSC concentrations at death vary across tissues and species. Here we present results of an experiment that aimed to determine minimum NSC concentrations in different tissues of saplings of two broad-leaved tree species (Acer pseudoplatanus and Quercus petratea) exposed to lethal carbon starvation via continuous darkening. In addition, we investigated recovery rates of NSC concentrations in saplings that had been darkened for different periods of time and were then re-exposed to light. Both species survived continuous darkening for about 12 weeks (confirmed by testing the ability to re-sprout after darkness). In all investigated tissues, starch concentrations declined close to zero within three to six weeks of darkness. Low molecular sugars also decreased strongly within the first weeks of darkness, but seemed to stabilize at low concentrations of 0.5 to 2 % dry matter (depending on tissue and species) almost until death. NSC concentrations recovered surprisingly fast in saplings that were re-exposed to light. After 3 weeks of continuous darkness, tissue NSC concentrations recovered within 6 weeks to levels of unshaded control saplings in all tissues and in both species. To our knowledge, this study represents the first experimental attempt to quantify minimum tissue NSC concentrations at lethal carbon starvation. Most importantly, our results suggest that carbon-starved tree saplings are able to

  18. Development and application of a sensitive method to determine concentrations of acrolein and other carbonyls in ambient air.

    PubMed

    Cahill, Thomas M; Charles, M Judith; Seaman, Vincent Y

    2010-05-01

    Acrolein, an unsaturated aldehyde, has been identified as one of the most important toxic air pollutants in recent assessments of ambient air quality. Current methods for determining acrolein concentrations, however, suffer from poor sensitivity, selectivity, and reproducibility. The collection and analysis of unsaturated carbonyls, and acrolein in particular, is complicated by unstable derivatives, coelution of similar compounds, and ozone interference. The primary objective of this research was to develop an analytical method to measure acrolein and other volatile carbonyls present in low part-per-trillion concentrations in ambient air samples obtained over short sampling periods. The method we devised uses a mist chamber in which carbonyls from air samples form water-soluble adducts with bisulfite in the chamber solution, effectively trapping the carbonyls in the solution. The mist chamber methodology proved effective, with collection efficiency for acrolein of at least 70% for each mist chamber at a flow rate of approximately 17 L/min. After the sample collection, the carbonyls are liberated from the bisulfite adducts through the addition of hydrogen peroxide, which converts the bisulfite to sulfate, reversing the bisulfite addition reaction. The free carbonyls are then derivatized by o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA*), which stabilizes the analytes and makes them easier to detect by electron-capture negative ionization mass spectrometry (ECNI-MS). The derivatives are then extracted and analyzed by gas chromatography-mass spectrometry (GC-MS). The mist chamber method was applied in a field test to determine the extent of acrolein in ambient air near the Peace Bridge plaza in Buffalo, New York, an area of heavy traffic near a major border crossing between the United States and Canada. In addition, XAD-2 adsorbent cartridges coated with 2-(hydroxymethyl)piperidine (2-HMP) according to Occupational Safety and Health Administration (OSHA) Method

  19. Development and application of a sensitive method to determine concentrations of acrolein and other carbonyls in ambient air.

    PubMed

    Cahill, Thomas M; Charles, M Judith; Seaman, Vincent Y

    2010-05-01

    Acrolein, an unsaturated aldehyde, has been identified as one of the most important toxic air pollutants in recent assessments of ambient air quality. Current methods for determining acrolein concentrations, however, suffer from poor sensitivity, selectivity, and reproducibility. The collection and analysis of unsaturated carbonyls, and acrolein in particular, is complicated by unstable derivatives, coelution of similar compounds, and ozone interference. The primary objective of this research was to develop an analytical method to measure acrolein and other volatile carbonyls present in low part-per-trillion concentrations in ambient air samples obtained over short sampling periods. The method we devised uses a mist chamber in which carbonyls from air samples form water-soluble adducts with bisulfite in the chamber solution, effectively trapping the carbonyls in the solution. The mist chamber methodology proved effective, with collection efficiency for acrolein of at least 70% for each mist chamber at a flow rate of approximately 17 L/min. After the sample collection, the carbonyls are liberated from the bisulfite adducts through the addition of hydrogen peroxide, which converts the bisulfite to sulfate, reversing the bisulfite addition reaction. The free carbonyls are then derivatized by o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA*), which stabilizes the analytes and makes them easier to detect by electron-capture negative ionization mass spectrometry (ECNI-MS). The derivatives are then extracted and analyzed by gas chromatography-mass spectrometry (GC-MS). The mist chamber method was applied in a field test to determine the extent of acrolein in ambient air near the Peace Bridge plaza in Buffalo, New York, an area of heavy traffic near a major border crossing between the United States and Canada. In addition, XAD-2 adsorbent cartridges coated with 2-(hydroxymethyl)piperidine (2-HMP) according to Occupational Safety and Health Administration (OSHA) Method

  20. Particulate matter concentrations in residences: an intervention study evaluating stand-alone filters and air conditioners

    PubMed Central

    Batterman, S.; Du, L.; Mentz, G.; Mukherjee, B.; Parker, E.; Godwin, C.; Chin, J.-Y.; O'Toole, A.; Robins, T.; Rowe, Z.; Lewis, T.

    2014-01-01

    This study, a randomized controlled trial, evaluated the effectiveness of free-standing air filters and window air conditioners (ACs) in 126 low-income households of children with asthma. Households were randomized into a control group, a group receiving a free-standing HEPA filter placed in the child's sleeping area, and a group receiving the filter and a window-mounted AC. Indoor air quality (IAQ) was monitored for week-long periods over three to four seasons. High concentrations of particulate matter (PM) and carbon dioxide were frequently seen. When IAQ was monitored, filters reduced PM levels in the child's bedroom by an average of 50%. Filter use varied greatly among households and declined over time, for example, during weeks when pollutants were monitored, filter use was initially high, averaging 84 ± 27%, but dropped to 63 ± 33% in subsequent seasons. In months when households were not visited, use averaged only 34 ± 30%. Filter effectiveness did not vary in homes with central or room ACs. The study shows that measurements over multiple seasons are needed to characterize air quality and filter performance. The effectiveness of interventions using free-standing air filters depends on occupant behavior, and strategies to ensure filter use should be an integral part of interventions. PMID:22145709

  1. Natural ³⁷Ar concentrations in soil air: implications for monitoring underground nuclear explosions.

    PubMed

    Riedmann, Robin A; Purtschert, Roland

    2011-10-15

    For on-site inspections (OSI) under the Comprehensive Nuclear-Test-Ban Treaty (CTBT) measurement of the noble gas ³⁷Ar is considered an important technique. ³⁷Ar is produced underground by neutron activation of Calcium by the reaction ⁴⁰Ca(n,α)³⁷Ar. The naturally occurring equilibrium ³⁷Ar concentration balance in soil air is a function of an exponentially decreasing production rate from cosmic ray neutrons with increasing soil depth, diffusive transport in the soil air, and radioactive decay (T(1/2): 35 days). In this paper for the first time, measurements of natural ³⁷Ar activities in soil air are presented. The highest activities of ~100 mBq m⁻³ air are 2 orders of magnitude larger than in the atmosphere and are found in 1.5-2.5 m depth. At depths > 8 m ³⁷Ar activities are < 20 mBq m⁻³ air. After identifying the main ³⁷Ar production and gas transport factors the expected global activity range distribution of ³⁷Ar in shallow subsoil (0.7 m below the surface) was estimated. In high altitude soils, with large amounts of Calcium and with low gas permeability, ³⁷Ar activities may reach values up to 1 Bq m⁻³.

  2. Threshold scaling limits of RO concentrates flowing in a long waste disposal pipeline.

    PubMed

    Semiat, R; Hasson, D; Zelmanov, G; Hemo, I

    2004-01-01

    Disposal of RO concentrates emanating from inland brackish water desalination plants presents a difficult environmental problem. The solution adopted by Mekorot--the National Water Company of Israel--is to construct a 30 km waste disposal pipeline for collecting concentrates emanating from several RO desalination plants and discharging them into the sea. The discharged concentrates are highly supersaturated with respect to CaCO3. Scale precipitation during concentrate flow through the RO module is inhibited by the presence of anti-scalants. The retention time of the concentrate solution in the discharge pipe will exceed 100 hours. This raises the issue of the risk of scale precipitation in the discharge pipe that could impair its proper functioning. The aim of the present study was to provide data for guiding the design and operation of the disposal pipeline. The extent of the induction period prior to the onset of precipitation was measured in a pilot plant simulating flow of concentrate solutions dosed with anti-scalants. The parameters investigated were the scaling potential, the anti-scalant concentration and the presence of a mixture of several anti-scalants. The results of this study provide threshold scaling limits under various conditions.

  3. 40 CFR 60.1920 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ....1920 What are the emission limits for air curtain incinerators that burn 100 percent yard waste? If your air curtain incinerator combusts 100 percent yard waste, you must only meet the emission limits in... curtain incinerators that burn 100 percent yard waste? 60.1920 Section 60.1920 Protection of...

  4. 10 CFR Appendix A to Part 835 - Derived Air Concentrations (DAC) for Controlling Radiation Exposure to Workers at DOE Facilities

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Derived Air Concentrations (DAC) for Controlling Radiation... RADIATION PROTECTION Pt. 835, App. A Appendix A to Part 835—Derived Air Concentrations (DAC) for Controlling Radiation Exposure to Workers at DOE Facilities The data presented in appendix A are to be used...

  5. Detecting terrestrial nutrient limitation: a global meta-analysis of foliar nutrient concentrations after fertilization

    NASA Astrophysics Data System (ADS)

    Ostertag, Rebecca; DiManno, Nicole

    2016-03-01

    Examining foliar nutrient concentrations after fertilization provides an alternative method for detecting nutrient limitation of ecosystems, which is logistically simpler to measure than biomass change. We present a meta-analysis of response ratios of foliar nitrogen and phosphorus (RRN, RRP) after addition of fertilizer of nitrogen (N), phosphorus (P), or the two elements in combination, in relation to climate, ecosystem type, life form, family, and methodological factors. Results support other meta-analyses using biomass, and demonstrate there is strong evidence for nutrient limitation in natural communities. However, because N fertilization experiments greatly outnumber P fertilization trials, it is difficult to discern the absolute importance of N vs. P vs. co-limitation across ecosystems. Despite these caveats, it is striking that results did not follow "conventional wisdom" that temperate ecosystems are N-limited and tropical ones are P-limited. In addition, the use of ratios of N-to-P rather than response ratios also are a useful index of nutrient limitation, but due to large overlap in values, there are unlikely to be universal cutoff values for delimiting N vs. P limitation. Differences in RRN and RRP were most significant across ecosystem types, plant families, life forms, and between competitive environments, but not across climatic variables.

  6. Air quality in postunification Erfurt, East Germany: associating changes in pollutant concentrations with changes in emissions.

    PubMed Central

    Ebelt, S; Brauer, M; Cyrys, J; Tuch, T; Kreyling, W G; Wichmann, H E; Heinrich, J

    2001-01-01

    The unification of East and West Germany in 1990 resulted in sharp decreases in emissions of major air pollutants. This change in air quality has provided an opportunity for a natural experiment to evaluate the health impacts of air pollution. We evaluated airborne particle size distribution and gaseous co-pollutant data collected in Erfurt, Germany, throughout the 1990s and assessed the extent to which the observed changes are associated with changes in the two major emission sources: coal burning for power production and residential heating, and motor vehicles. Continuous data for sulfur dioxide, total suspended particulates (TSP), nitric oxide, carbon monoxide, and meteorologic parameters were available for 1990-1999, and size-selective particle number and mass concentration measurements were made during winters of 1991 and 1998. We used hourly profiles of pollutants and linear regression analyses, stratified by year, weekday/weekend, and hour, using NO and SO(2) as markers of traffic- and heating-related combustion sources, respectively, to study the patterns of various particle size fractions. Supplementary data on traffic and heating-related sources were gathered to support hypotheses linking these sources with observed changes in ambient air pollution levels. Substantially decreased (19-91%) concentrations were observed for all pollutants, with the exception of particles in the 0.01-0.03 microm size range (representing the smallest ultrafine particles that were measured). The number concentration for these particles increased by 115% between 1991 and 1998. The ratio of these ultrafine particles to TSP also increased by more than 500%, indicating a dramatic change in the size distribution of airborne particles. Analysis of hourly concentration patterns indicated that in 1991, concentrations of SO(2) and larger particle sizes were related to residential heating with coal. These peaks were no longer evident in 1998 due to decreases in coal consumption and

  7. Variation and balance of positive air ion concentrations in a boreal forest

    NASA Astrophysics Data System (ADS)

    Hõrrak, U.; Aalto, P. P.; Salm, J.; Komsaare, K.; Tammet, H.; Mäkelä, J. M.; Laakso, L.; Kulmala, M.

    2008-02-01

    Air ions are characterized on the basis of measurements carried out in a boreal forest at the Hyytiälä SMEAR station, Finland, during the BIOFOR III campaign in spring 1999. The air ions were discriminated as small ions (charged molecular aggregates of the diameter of less than 2.5 nm), intermediate ions (charged aerosol particles of the diameter of 2.5-8 nm), and large ions (charged aerosol particles of the diameter of 8-20 nm). Statistical characteristics of the ion concentrations and the parameters of ion balance in the atmosphere are presented separately for the nucleation event days and non-event days. In the steady state, the ionization rate is balanced with the loss of small ions, which is expressed as the product of the small ion concentration and the ion sink rate. The widely known sinks of small ions are the recombination with small ions of opposite polarity and attachment to aerosol particles. The dependence of small ion concentration on the concentration of aerosol particles was investigated applying a model of the bipolar diffusion charging of particles by small ions. When the periods of relative humidity above 95% and wind speed less than 0.6 m s-1 were excluded, then the small ion concentration and the theoretically calculated small ion sink rate were closely negatively correlated (correlation coefficient -87%). However, an extra ion loss term of the same magnitude as the ion loss onto aerosol particles is needed for a quantitative explanation of the observations. This term is presumably due to the small ion deposition on coniferous forest. The hygroscopic growth correction of the measured aerosol particle size distributions was also found to be necessary for the proper estimation of the ion sink rate. In the case of nucleation burst events, the concentration of small positive ions followed the general balance equation, no extra ion loss in addition to the deposition on coniferous forest was detected, and the hypothesis of the conversion of ions

  8. Spatial and temporal distribution of pesticide air concentrations in Canadian agricultural regions

    NASA Astrophysics Data System (ADS)

    Yao, Yuan; Tuduri, Ludovic; Harner, Tom; Blanchard, Pierrette; Waite, Don; Poissant, Laurier; Murphy, Clair; Belzer, Wayne; Aulagnier, Fabien; Li, Yi-Fan; Sverko, Ed

    The Canadian Pesticide Air Sampling Campaign was initiated in 2003 to assess atmospheric levels of pesticides, especially currently used pesticides (CUPs) in agricultural regions across Canada. In the first campaign during the spring to summer of 2003, over 40 pesticides were detected. The spatial and temporal distribution of pesticides in the Canadian atmosphere was shown to reflect the pesticide usage in each region. Several herbicides including triallate, bromoxynil, MCPA, 2,4-D, dicamba, trifluralin and ethalfluralin were detected at highest levels at Bratt's Lake, SK in the prairie region. Strong relationships between air concentrations and dry depositions were observed at this site. Although no application occurred in the Canadian Prairies in 2003, high air concentrations of lindane ( γ-hexachlorocyclohexane) were still observed at Bratt's Lake and Hafford, SK. Two fungicides (chlorothalonil and metalaxyl) and two insecticides (endosulfan and carbofuran) were measured at highest levels at Kensington, PEI. Maximum concentrations of chlorpyrifos and metolachlor were found at St. Anicet, QC. The southern Ontario site, Egbert showed highest concentration of alachlor. Malathion was detected at the highest level at the west coast site, Abbotsford, BC. In case of legacy chlorinated insecticides, high concentrations of DDT, DDE and dieldrin were detected in British Columbia while α-HCH and HCB were found to be fairly uniform across the country. Chlordane was detected in Ontario, Québec and Prince Edward Island. This study demonstrates that the sources for the observed atmospheric occurrence of pesticides include local current pesticide application, volatilization of pesticide residues from soil and atmospheric transport. In many instances, these data represent the first measurements for certain pesticides in a given part of Canada.

  9. Fibrinogen concentrate improves survival during limited resuscitation of uncontrolled hemorrhagic shock in a Swine model.

    PubMed

    White, Nathan J; Wang, Xu; Liles, Conrad; Stern, Susan

    2014-11-01

    The purpose of this study was to evaluate the effect of fibrinogen concentrate, as a hemostatic agent, on limited resuscitation of uncontrolled hemorrhagic shock. We use a swine model of hemorrhagic shock with free bleeding from a 4-mm aortic tear to test the effect of adding a one-time dose of fibrinogen concentrate given at the onset of limited fluid resuscitation. Immature female swine were anesthetized and subjected to catheter hemorrhage and aortic tear to induce uniform hemorrhagic shock. Animals (n = 7 per group) were then randomized to receive (i) no fluid resuscitation (neg control) or (ii) limited resuscitation in the form of two boluses of 10 mL/kg of 6% hydroxyethyl starch solution given 30 min apart (HEX group), or (iii) the same fluid regimen with one dose of 120-mg/kg fibrinogen concentrate given with the first hydroxyethyl starch bolus (FBG). Animals were then observed for a total of 6 h with aortic repair and aggressive resuscitation with shed blood taking place at 3 h. Survival to 6 h was significantly increased with FBG (7/8, 86%) versus HEX (2/7, 29%) and neg control (0/7, 0%) (FBG vs. HEX, Kaplan-Meier log-rank P = 0.035). Intraperitoneal blood loss adjusted for survival time was increased in HEX (0.4 mL/kg per minute) when compared with FBG (0.1 mg/kg per minute, P = 0.047) and neg control (0.1 mL/kg per minute, P = 0.041). Systemic and cerebral hemodynamics also showed improvement with FBG versus HEX. Fibrinogen concentrate may be a useful adjunct to decrease blood loss, improve hemodynamics, and prolong survival during limited resuscitation of uncontrolled hemorrhagic shock.

  10. Inhalation of concentrated ambient air particles exacerbates myocardial ischemia in conscious dogs.

    PubMed Central

    Wellenius, Gregory A; Coull, Brent A; Godleski, John J; Koutrakis, Petros; Okabe, Kazunori; Savage, Sara T; Lawrence, Joy E; Murthy, G G Krishna; Verrier, Richard L

    2003-01-01

    Short-term increases in ambient air pollution have been associated with an increased incidence of acute cardiac events. We assessed the effect of inhalation exposure to concentrated ambient particles (CAPs) on myocardial ischemia in a canine model of coronary artery occlusion. Six mongrel dogs underwent thoracotomy for implantation of a vascular occluder around the left anterior descending coronary artery and tracheostomy to facilitate particulate exposure. After recovery (5-13 weeks), pairs of subjects were exposed for 6 hr/day on 3 or 4 consecutive days. Within each pair, one subject was randomly assigned to breathe CAPs on the second exposure day and filtered air at other times. The second subject breathed CAPs on the third exposure day and filtered air at other times. Immediately after each exposure, subjects underwent 5-min coronary artery occlusion. We determined ST-segment elevation, a measure of myocardial ischemia heart rate, and arrhythmia incidence during occlusion from continuous electrocardiograms. Exposure to CAPs (median, 285.7; range, 161.3-957.3 microg/m3) significantly (p = 0.007) enhanced occlusion-induced peak ST-segment elevation in precordial leads V4 (9.4 +/- 1.7 vs. 6.2 +/- 0.9 mm, CAPs vs. filtered air, respectively) and V5 (9.2 +/- 1.3 vs. 7.5 +/- 0.9 mm). ST-segment elevation was significantly correlated with the silicon concentration of the particles and other crustal elements possibly associated with urban street dust (p = 0.003 for Si). No associations were found with CAPs mass or number concentrations. Heart rate was not affected by CAPs exposure. These results suggest that exacerbation of myocardial ischemia during coronary artery occlusion may be an important mechanism of environmentally related acute cardiac events. PMID:12676590

  11. Predictive model for diffusion-limited aggregation kinetics of nanocolloids under high concentration.

    PubMed

    Lattuada, Marco

    2012-01-12

    Smoluchowski's equation for the rate of aggregation of colloidal particles under diffusion-limited conditions has set the basis for the interpretation of kinetics of aggregation phenomena. Nevertheless, its use is limited to sufficiently dilute conditions. In this work we propose a correction to Smoluchowski's equation by using a result derived by Richards ( J. Phys. Chem. 1986 , 85 , 3520 ) within the framework of trapping theory. This corrected aggregation kernel, which accounts for concentration dependence effects, has been implemented in a population-balance equations scheme and used to model the aggregation kinetics of colloidal particles undergoing diffusion-limited aggregation under concentrated conditions (up to a particle volume fraction of 30%). The predictions of population balance calculations have been validated by means of Brownian dynamic simulations. It was found that the corrected kernel can very well reproduce the results from Brownian dynamic simulations for all concentration values investigated, and is also able to accurately predict the time required by a suspension to reach the gel point. On the other hand, classical Smoluchowski's theory substantially underpredicts the rate of aggregation as well as the onset of gelation, with deviations becoming progressively more severe as the particle volume fraction increases. PMID:22148884

  12. [Airborne Fungal Aerosol Concentration and Distribution Characteristics in Air- Conditioned Wards].

    PubMed

    Zhang, Hua-ling; Feng, He-hua; Fang, Zi-liang; Wang, Ben-dong; Li, Dan

    2015-04-01

    The effects of airborne fungus on human health in the hospital environment are related to not only their genera and concentrations, but also their particle sizes and distribution characteristics. Moreover, the mechanisms of aerosols with different particle sizes on human health are different. Fungal samples were obtained in medicine wards of Chongqing using a six-stage sampler. The airborne fungal concentrations, genera and size distributions of all the sampling wards were investigated and identified in detail. Results showed that airborne fungal concentrations were not correlated to the diseases or personnel density, but were related to seasons, temperature, and relative humidity. The size distribution rule had roughly the same for testing wards in winter and summer. The size distributions were not related with diseases and seasons, the percentage of airborne fungal concentrations increased gradually from stage I to stage III, and then decreased dramatically from stage V to stage VI, in general, the size of airborne fungi was a normal distribution. There was no markedly difference for median diameter of airborne fungi which was less 3.19 μm in these wards. There were similar dominant genera in all wards. They were Aspergillus spp, Penicillium spp and Alternaria spp. Therefore, attention should be paid to improve the filtration efficiency of particle size of 1.1-4.7 μm for air conditioning system of wards. It also should be targeted to choose appropriate antibacterial methods and equipment for daily hygiene and air conditioning system operation management.

  13. Seasonal variation in vertical volatile compounds air concentrations within a remote hemiboreal mixed forest

    NASA Astrophysics Data System (ADS)

    Noe, S. M.; Hüve, K.; Niinemets, Ü.; Copolovici, L.

    2011-05-01

    The vertical distribution of ambient biogenic volatile organic compounds (BVOC) concentrations within a hemiboreal forest canopy was investigated over a period of one year. Variability in temporal and spatial isoprene concentrations can be mainly explained by biogenic emissions from deciduous trees, ranging from 0.1 to 7.5 μg m-3. Monoterpene concentrations exceeded isoprene largely and ranged from 0.01 to 140 μg m-3 and during winter time anthropogenic contributions are likely. Variation in monoterpene concentrations found to be largest right above the ground and the vertical profile suggest a weak mixing leading to terpene accumulation in the lower canopy. Exceptionally high values were recorded during a heat wave in July 2010 with very high midday temperatures above 30 °C for several weeks. During summer months, monoterpene exceeded isoprene concentrations 6-fold and during winter 12-fold. The relative contribution of diverse monoterpene species to the ambient concentrations revealed a dominance of α-pinene in the lower and of limonene in the upper part of the canopy, both accounting for up to 70 % of the total monoterpene concentration during summer months. The main contributing monoterpene during wintertime was Δ3-carene accounting for 60 % of total monoterpene concentration in January. Possible biogenic monoterpene sources beside the foliage are the leaf litter, the soil and also resins exuding from stems. In comparison, the hemiboreal mixed forest canopy showed similar isoprene but higher monoterpene concentrations than the boreal forest and lower isoprene but substantially higher monoterpene concentrations than the temperate mixed forest canopies. These results have major implications for simulating air chemistry and secondary organic aerosol formation within and above hemiboreal forest canopies.

  14. Study of boron detection limit using the in-air PIGE set-up at LAMFI-USP

    NASA Astrophysics Data System (ADS)

    Moro, M. V.; Silva, T. F.; Trindade, G. F.; Added, N.; Tabacniks, M. H.

    2014-11-01

    The quantification of small amounts of boron in materials is of extreme importance in different areas of materials science. Boron is an important contaminant and also a silicon dopant in the semiconductor industry. Boron is also extensively used in nuclear power plants, either for neutron shielding or for safety control and boron is an essential nutrient for life, either vegetable or animal. The production of silicon solar cells, by refining metallurgical-grade silicon (MG-Si) requires the control and reduction of several silicon contaminants to very low concentration levels. Boron is one of the contaminants of solar-grade silicon (SG-Si) that must be controlled and quantified at sub-ppm levels. In the metallurgical purification, boron quantification is usually made by Inductive Coupled Plasma Mass Spectrometry, (ICP-MS) but the results need to be verified by an independent analytical method. In this work we present the results of the analysis of silicon samples by Particle Induced Gamma-Ray Emission (PIGE) aiming the quantification of low concentrations of boron. PIGE analysis was carried out using the in-air external beam line of the Laboratory for Materials Analysis with Ion Beans (LAMFI-USP) by the 10B ( p ,αγ(7Be nuclear reaction, and measuring the 429 keV γ-ray. The in-air PIGE measurements at LAMFI have a quantification limit of the order of 1016 at/cm2.

  15. Study of boron detection limit using the in-air PIGE set-up at LAMFI-USP

    SciTech Connect

    Moro, M. V.; Silva, T. F.; Trindade, G. F.; Added, N.; Tabacniks, M. H.

    2014-11-11

    The quantification of small amounts of boron in materials is of extreme importance in different areas of materials science. Boron is an important contaminant and also a silicon dopant in the semiconductor industry. Boron is also extensively used in nuclear power plants, either for neutron shielding or for safety control and boron is an essential nutrient for life, either vegetable or animal. The production of silicon solar cells, by refining metallurgical-grade silicon (MG-Si) requires the control and reduction of several silicon contaminants to very low concentration levels. Boron is one of the contaminants of solar-grade silicon (SG-Si) that must be controlled and quantified at sub-ppm levels. In the metallurgical purification, boron quantification is usually made by Inductive Coupled Plasma Mass Spectrometry, (ICP-MS) but the results need to be verified by an independent analytical method. In this work we present the results of the analysis of silicon samples by Particle Induced Gamma-Ray Emission (PIGE) aiming the quantification of low concentrations of boron. PIGE analysis was carried out using the in-air external beam line of the Laboratory for Materials Analysis with Ion Beams (LAMFI-USP) by the {sup 10}B(p,αγ({sup 7}Be nuclear reaction, and measuring the 429 keV γ-ray. The in-air PIGE measurements at LAMFI have a quantification limit of the order of 10{sup 16} at/cm{sup 2}.

  16. VOCs Emissions from Multiple Wood Pellet Types and Concentrations in Indoor Air

    PubMed Central

    Soto-Garcia, Lydia; Ashley, William J.; Bregg, Sandar; Walier, Drew; LeBouf, Ryan; Hopke, Philip K.; Rossner, Alan

    2016-01-01

    Wood pellet storage safety is an important aspect for implementing woody biomass as a renewable energy source. When wood pellets are stored indoors in large quantities (tons) in poorly ventilated spaces in buildings, such as in basements, off-gassing of volatile organic compounds (VOCs) can significantly affect indoor air quality. To determine the emission rates and potential impact of VOC emissions, a series of laboratory and field measurements were conducted using softwood, hardwood, and blended wood pellets manufactured in New York. Evacuated canisters were used to collect air samples from the headspace of drums containing pellets and then in basements and pellet storage areas of homes and small businesses. Multiple peaks were identified during GC/MS and GC/FID analysis, and four primary VOCs were characterized and quantified: methanol, pentane, pentanal, and hexanal. Laboratory results show that total VOCs (TVOCs) concentrations for softwood (SW) were statistically (p < 0.02) higher than blended or hardwood (HW) (SW: 412 ± 25; blended: 203 ± 4; HW: 99 ± 8, ppb). The emission rate from HW was the fastest, followed by blended and SW, respectively. Emissions rates were found to range from 10−1 to 10−5 units, depending upon environmental factors. Field measurements resulted in airborne concentrations ranging from 67 ± 8 to 5000 ± 3000 ppb of TVOCs and 12 to 1500 ppb of aldehydes, with higher concentrations found in a basement with a large fabric bag storage unit after fresh pellet delivery and lower concentrations for aged pellets. These results suggest that large fabric bag storage units resulted in a substantial release of VOCs into the building air. Occupants of the buildings tested discussed concerns about odor and sensory irritation when new pellets were delivered. The sensory response was likely due to the aldehydes. PMID:27022205

  17. Effect of geocoding errors on traffic-related air pollutant exposure and concentration estimates.

    PubMed

    Ganguly, Rajiv; Batterman, Stuart; Isakov, Vlad; Snyder, Michelle; Breen, Michael; Brakefield-Caldwell, Wilma

    2015-01-01

    Exposure to traffic-related air pollutants is highest very near roads, and thus exposure estimates are sensitive to positional errors. This study evaluates positional and PM2.5 concentration errors that result from the use of automated geocoding methods and from linearized approximations of roads in link-based emission inventories. Two automated geocoders (Bing Map and ArcGIS) along with handheld GPS instruments were used to geocode 160 home locations of children enrolled in an air pollution study investigating effects of traffic-related pollutants in Detroit, Michigan. The average and maximum positional errors using the automated geocoders were 35 and 196 m, respectively. Comparing road edge and road centerline, differences in house-to-highway distances averaged 23 m and reached 82 m. These differences were attributable to road curvature, road width and the presence of ramps, factors that should be considered in proximity measures used either directly as an exposure metric or as inputs to dispersion or other models. Effects of positional errors for the 160 homes on PM2.5 concentrations resulting from traffic-related emissions were predicted using a detailed road network and the RLINE dispersion model. Concentration errors averaged only 9%, but maximum errors reached 54% for annual averages and 87% for maximum 24-h averages. Whereas most geocoding errors appear modest in magnitude, 5% to 20% of residences are expected to have positional errors exceeding 100 m. Such errors can substantially alter exposure estimates near roads because of the dramatic spatial gradients of traffic-related pollutant concentrations. To ensure the accuracy of exposure estimates for traffic-related air pollutants, especially near roads, confirmation of geocoordinates is recommended.

  18. Cleaning Products and Air Fresheners: Emissions and ResultingConcentrations of Glycol Ethers and Terpenoids

    SciTech Connect

    Singer, Brett C.; Destaillat, Hugo; Hodgson, Alfred T.; Nazaroff,William W.

    2005-08-01

    Experiments were conducted to quantify emissions and concentrations of glycol ethers and terpenoids from cleaning product and air freshener use in a 50-m{sup 3} room ventilated at {approx}0.5 h{sup -1}. Five cleaning products were applied full-strength (FS); three were additionally used in dilute solution. FS application of pine-oil cleaner (POC) yielded 1-h concentrations of 10-1300 {micro}g m{sup -3} for individual terpenoids, including {alpha}-terpinene (90-120), d-limonene (1000-1100), terpinolene (900-1300), and {alpha}-terpineol (260-700). One-hour concentrations of 2-butoxyethanol and/or dlimonene were 300-6000 {micro}g m{sup -3} after FS use of other products. During FS application including rinsing with sponge and wiping with towels, fractional emissions (mass volatilized/dispensed) of 2-butoxyethanol and d-limonene were 50-100% with towels retained, {approx}25-50% when towels were removed after cleaning. Lower fractions (2-11%) resulted from dilute use. Fractional emissions of terpenes from FS use of POC were {approx}35-70% with towels retained, 20-50% with towels removed. During floor cleaning with dilute solution of POC, 7-12% of dispensed terpenes were emitted. Terpene alcohols were emitted at lower fractions: 7-30% (FS, towels retained), 2-9% (FS, towels removed), and 2-5% (dilute). During air-freshener use, d-limonene, dihydromyrcenol, linalool, linalyl acetate, and {beta}-citronellol were emitted at 35-180 mg d{sup -1} over three days while air concentrations averaged 30-160 {micro}g m{sup -3}.

  19. Effect of geocoding errors on traffic-related air pollutant exposure and concentration estimates

    PubMed Central

    Ganguly, Rajiv; Batterman, Stuart; Isakov, Vlad; Snyder, Michelle; Breen, Michael; Brakefield-Caldwell, Wilma

    2015-01-01

    Exposure to traffic-related air pollutants is highest very near roads, and thus exposure estimates are sensitive to positional errors. This study evaluates positional and PM2.5 concentration errors that result from the use of automated geocoding methods and from linearized approximations of roads in link-based emission inventories. Two automated geocoders (Bing Map and ArcGIS) along with handheld GPS instruments were used to geocode 160 home locations of children enrolled in an air pollution study investigating effects of traffic-related pollutants in Detroit, Michigan. The average and maximum positional errors using the automated geocoders were 35 and 196 m, respectively. Comparing road edge and road centerline, differences in house-to-highway distances averaged 23 m and reached 82 m. These differences were attributable to road curvature, road width and the presence of ramps, factors that should be considered in proximity measures used either directly as an exposure metric or as inputs to dispersion or other models. Effects of positional errors for the 160 homes on PM2.5 concentrations resulting from traffic-related emissions were predicted using a detailed road network and the RLINE dispersion model. Concentration errors averaged only 9%, but maximum errors reached 54% for annual averages and 87% for maximum 24-h averages. Whereas most geocoding errors appear modest in magnitude, 5% to 20% of residences are expected to have positional errors exceeding 100 m. Such errors can substantially alter exposure estimates near roads because of the dramatic spatial gradients of traffic-related pollutant concentrations. To ensure the accuracy of exposure estimates for traffic-related air pollutants, especially near roads, confirmation of geocoordinates is recommended. PMID:25670023

  20. Pt-TiO2/MWCNTs Hybrid Composites for Monitoring Low Hydrogen Concentrations in Air

    PubMed Central

    Trocino, Stefano; Donato, Andrea; Latino, Mariangela; Donato, Nicola; Leonardi, Salvatore Gianluca; Neri, Giovanni

    2012-01-01

    Hydrogen is a valuable fuel for the next energy scenario. Unfortunately, hydrogen is highly flammable at concentrations higher than 4% in air. This aspect makes the monitoring of H2 leaks an essential issue for safety reasons, especially in the transportation field. In this paper, nanocomposites based on Pt-doped TiO2/multiwalled carbon nanotubes (MWCNTs) have been introduced as sensitive materials for H2 at low temperatures. Pt-TiO2/MWNTs nanocomposites with different composition have been prepared by a simple wet chemical procedure and their morphological, microstructural and electrical properties were investigated. Resistive thick-film devices have been fabricated printing the hybrid nanocomposites on alumina substrates provided with Pt interdigitated electrodes. Electrical tests in air have shown that embedding MWCNTs in the TiO2 matrix modify markedly the electrical conductivity, providing a means to decrease the resistance of the sensing layer. Pt acts as a catalytic additive. Pt-TiO2/MWNTs-based sensors were found to be sensitive to hydrogen at concentrations between 0.5 and 3% in air, satisfying the requisites for practical applications in hydrogen leak detection devices.

  1. Modeling breathing-zone concentrations of airborne contaminants generated during compressed air spray painting.

    PubMed

    Flynn, M R; Gatano, B L; McKernan, J L; Dunn, K H; Blazicko, B A; Carlton, G N

    1999-01-01

    This paper presents a mathematical model to predict breathing-zone concentrations of airborne contaminants generated during compressed air spray painting in cross-flow ventilated booths. The model focuses on characterizing the generation and transport of overspray mist. It extends previous work on conventional spray guns to include exposures generated by HVLP guns. Dimensional analysis and scale model wind-tunnel studies are employed using non-volatile oils, instead of paint, to produce empirical equations for estimating exposure to total mass. Results indicate that a dimensionless breathing zone concentration is a nonlinear function of the ratio of momentum flux of air from the spray gun to the momentum flux of air passing through the projected area of the worker's body. The orientation of the spraying operation within the booth is also very significant. The exposure model requires an estimate of the contaminant generation rate, which is approximated by a simple impactor model. The results represent an initial step in the construction of more realistic models capable of predicting exposure as a mathematical function of the governing parameters. PMID:10028895

  2. Detonation propagation through methane-air mixtures with fuel concentration gradients

    NASA Astrophysics Data System (ADS)

    Kessler, David; Gamezo, Vadim; Oran, Elaine

    2010-11-01

    The complex structure of a multidimensional detonation front consists of constantly changing, multiply intersecting incident shocks and Mach stems followed by growing and shrinking regions of reacted and unreacted gases. Because these flow structures change in time, the energy release in the shocked and compressed gases varies in space and time. Trajectories of triple points formed at shock intersections create cellular patterns whose size and structure are characteristic of the particular material and the background condition. In high-activation-energy fuel-air mixtures, such as methane in air, cellular patterns are relatively large, very irregular, and have complex and changing substructures. Here we use numerical simulations to study the behavior of detonations propagating through methane-air mixtures with a spatial gradient of fuel concentration. When the mixture stoichiometry varies from stoichiometric, the detonation propagation speed slows and sizes of cellular structures grow. In partially premixed systems with a nonuniform concentration of fuel -- a condition that can occur, for example, naturally in sealed underground coal mine tunnels -- both the propagation speed and the characteristic detonation cell size vary spatially.

  3. High Concentrations of Organic Contaminants in Air from Ship Breaking Activities in Chittagong, Bangladesh.

    PubMed

    Nøst, Therese H; Halse, Anne K; Randall, Scott; Borgen, Anders R; Schlabach, Martin; Paul, Alak; Rahman, Atiqur; Breivik, Knut

    2015-10-01

    The beaches on the coast of Chittagong in Bangladesh are one of the most intense ship breaking areas in the world. The aim of the study was to measure the concentrations of organic contaminants in the air in the city of Chittagong, including the surrounding ship breaking areas using passive air samplers (N = 25). The compounds detected in the highest amounts were the polycyclic aromatic hydrocarbons (PAHs) and short-chain chlorinated paraffins (SCCPs), whereas dichlorodiphenyltrichloroethanes (DDTs), hexachlorobenzene (HCB), and polychlorinated biphenyls (PCBs) were several orders of magnitude lower in comparison. PCBs, PAHs, and HCB were highest at sites near the ship breaking activities, whereas DDTs and SCCPs were higher in the urban areas. Ship breaking activities likely act as atmospheric emission sources of PCBs, PAHs, and HCB, thus adding to the international emphasis on responsible recycling of ships. Concentrations of PAHs, PCBs, DDTs, HCB, and SCCPs in ambient air in Chittagong are high in comparison to those found in similar studies performed in other parts of Asia. Estimated toxic equivalent quotients indicate elevated human health risks caused by inhalation of PAHs at most sites. PMID:26351879

  4. High Concentrations of Organic Contaminants in Air from Ship Breaking Activities in Chittagong, Bangladesh.

    PubMed

    Nøst, Therese H; Halse, Anne K; Randall, Scott; Borgen, Anders R; Schlabach, Martin; Paul, Alak; Rahman, Atiqur; Breivik, Knut

    2015-10-01

    The beaches on the coast of Chittagong in Bangladesh are one of the most intense ship breaking areas in the world. The aim of the study was to measure the concentrations of organic contaminants in the air in the city of Chittagong, including the surrounding ship breaking areas using passive air samplers (N = 25). The compounds detected in the highest amounts were the polycyclic aromatic hydrocarbons (PAHs) and short-chain chlorinated paraffins (SCCPs), whereas dichlorodiphenyltrichloroethanes (DDTs), hexachlorobenzene (HCB), and polychlorinated biphenyls (PCBs) were several orders of magnitude lower in comparison. PCBs, PAHs, and HCB were highest at sites near the ship breaking activities, whereas DDTs and SCCPs were higher in the urban areas. Ship breaking activities likely act as atmospheric emission sources of PCBs, PAHs, and HCB, thus adding to the international emphasis on responsible recycling of ships. Concentrations of PAHs, PCBs, DDTs, HCB, and SCCPs in ambient air in Chittagong are high in comparison to those found in similar studies performed in other parts of Asia. Estimated toxic equivalent quotients indicate elevated human health risks caused by inhalation of PAHs at most sites.

  5. Combining regression analysis and air quality modelling to predict benzene concentration levels

    NASA Astrophysics Data System (ADS)

    Vlachokostas, Ch.; Achillas, Ch.; Chourdakis, E.; Moussiopoulos, N.

    2011-05-01

    State of the art epidemiological research has found consistent associations between traffic-related air pollution and various outcomes, such as respiratory symptoms and premature mortality. However, many urban areas are characterised by the absence of the necessary monitoring infrastructure, especially for benzene (C 6H 6), which is a known human carcinogen. The use of environmental statistics combined with air quality modelling can be of vital importance in order to assess air quality levels of traffic-related pollutants in an urban area in the case where there are no available measurements. This paper aims at developing and presenting a reliable approach, in order to forecast C 6H 6 levels in urban environments, demonstrated for Thessaloniki, Greece. Multiple stepwise regression analysis is used and a strong statistical relationship is detected between C 6H 6 and CO. The adopted regression model is validated in order to depict its applicability and representativeness. The presented results demonstrate that the adopted approach is capable of capturing C 6H 6 concentration trends and should be considered as complementary to air quality monitoring.

  6. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  7. The flammability limits of hydrogen and methane in air at moderately elevated temperatures

    SciTech Connect

    Ale, B.B.; Wierzba, I.

    1997-12-31

    The flammability limits of hydrogen and methane in air were determined experimentally at elevated initial mixture temperatures up to 350 C at atmospheric pressure for upward flame propagation in a conventional steel test tube apparatus. Additionally, the extent to which a prolonged exposure (i.e., residence time) of the mixture to elevated temperatures before spark ignition and, consequently, the existence of pre-ignition reactions that may influence the value of the lean and rich flammability limits was also investigated. It was shown that the flammability limits for methane widened approximately linearly with an increase in the initial mixture temperature over the whole range of temperatures tested. These limits were not affected by the length of the residence time before spark ignition. Different behavior was observed for flammability limits of hydrogen. They were also widened with an increase in the initial temperature but only up to 200 C. In this initial temperature range the limits were not affected by the length of the residence time. However, at initial temperature exceeding 200 C the flammability limits, especially, the rich limits narrowed with an increase in the temperature and were significantly affected by the residence time before spark ignition. It was suggested that the substantial drop in the value of the rich limit with the increase in the residence time was caused by the relatively low temperature catalytic reactions on the stainless steel surface of the flame tube. Simple method for calculating the hydrogen conversion to water was proposed. The results of calculations are in fair agreement with the experimental evidence.

  8. Seasonal variation in vertical volatile compounds air concentrations within a remote hemiboreal mixed forest

    NASA Astrophysics Data System (ADS)

    Noe, S. M.; Hüve, K.; Niinemets, Ü.; Copolovici, L.

    2012-05-01

    The vertical distribution of ambient biogenic volatile organic compounds (BVOC) concentrations within a hemiboreal forest canopy was investigated over a period of one year. Variability in temporal and spatial isoprene concentrations, ranging from 0.1 to 7.5 μg m-3, can be mainly explained by biogenic emissions from deciduous trees. Monoterpene concentrations exceeded isoprene largely and ranged from 0.01 to 140 μg m-3 and during winter time anthropogenic contributions are likely. Variation in monoterpene concentrations were found to be largest right above the ground and the vertical profiles suggest a weak mixing leading to terpene accumulation in the lower canopy. Exceptionally high values were recorded during a heat wave in July 2010 with very high midday temperatures above 30 °C for several weeks. During summer months, monoterpene exceeded isoprene concentrations 6-fold and during winter 12-fold. During summer months, dominance of α-pinene in the lower and of limonene in the upper part of the canopy was observed, both accounting for up to 70% of the total monoterpene concentration. During wintertime, Δ3-carene was the dominant species, accounting for 60% of total monoterpene concentration in January. Possible biogenic monoterpene sources beside the foliage are the leaf litter, the soil and also resins exuding from stems. In comparison, the hemiboreal mixed forest canopy showed similar isoprene but higher monoterpene concentrations than the boreal forest and lower isoprene but substantially higher monoterpene concentrations than the temperate mixed forest canopies. These results have major implications for simulating air chemistry and secondary organic aerosol formation within and above hemiboreal forest canopies. Possible effects of in-cartridge oxidation reactions are discussed as our measurement technique did not include oxidant scavenging. A comparison between measurements with and without scavenging oxidants is presented.

  9. Dynamics of flames near the rich-flammability limit of hydrogen-air mixtures

    NASA Technical Reports Server (NTRS)

    Kailasanath, K.; Ganguly, K.; Patnaik, G.

    1993-01-01

    Flames near the rich-flammability limit of hydrogen-air mixtures are studied using a detailed, time-dependent, one-dimensional Lagrangian model. Results from the numerical simulations indicate that a steady burning velocity is not obtained for very rich hydrogen-air mixtures. As the amount of hydrogen is increased, a damped oscillation is observed in the flame and burning velocities, and then, with further increase in the amount of hydrogen, an undamped oscillation with a complex set of frequencies is observed. Simulations with a simplified one-step irreversible chemical reaction do not show these oscillations, suggesting that chemical kinetics plays a strong role in inducing these oscillations. Further analysis shows that the oscillations are due to a competition for H atoms between chain branching and chain-terminating reactions. Simulations of spherically expanding flames suggest that stretch effects (due to curvature) will cause the oscillations to occur in less rich mixtures than that observed for planar flames. The implications of these oscillations on the rich-flammability limit as well as the role of chemical kinetics in creating a fundamental flammability limit is discussed.

  10. A longitudinal study of the relation of lead in blood to lead in air concentrations among battery workers.

    PubMed

    Hodgkins, D G; Robins, T G; Hinkamp, D L; Schork, M A; Krebs, W H

    1992-04-01

    The relation between lead in air (PbA) and lead in blood (PbB), concentrations was investigated among 44 workers in five major operations in a United States high volume, lead acid battery plant. The study covered a 30 month period in which workers received frequent PbA and PbB determinations, workers remained in a single job, and PbA concentrations averaged below the US Occupational Safety and Health Administration (OSHA) permissible exposure limit of 50 micrograms/m3. In both univariate and multivariable linear regressions, longitudinal analyses averaging PbA concentrations over the 30 month study period appeared superior to cross sectional analyses using only six month PbA averages to model PbB concentrations. The covariate adjusted coefficient (alpha value) for PbA (mu/m3) in models of PbB (micrograms/100 g) was 1.14. This figure is strikingly higher than that reported in previous studies in the lead acid battery industry in all of which PbA concentrations were substantially higher than in the current study. Plausible explanations for the difference in alpha values include non-linearity of the PbA-PbB curve, a higher fraction of large size particulate associated with higher PbA concentrations, survivor bias among workers exposed to higher PbA concentrations, and the cross sectional designs of most previous studies. Despite previously reported problems with the model used by OSHA to predict PbA-PbB relations, the findings of this study are in good agreement with the predictions of that model.

  11. Inverse dependency of particle residence times in ponds to the concentration of phosphate, the limiting nutrient.

    PubMed

    Roberts, Kimberly A; Santschi, Peter H

    2004-01-01

    234Th, a commonly used short-lived particle-reactive tracer in marine systems, was measured in three different holding pond series at the Rocky Flats Environmental Technology Site (RFETS), Colorado, along with its parent nuclide 238U, to determine steady-state residence times of particle-reactive actinides such as Pu, and of particles. Series B ponds, which received industrial effluent that includes ortho-phosphate (PO4) and actinides, differed from series A and C ponds, which did not. This difference was also evident in the calculated particle residence times, which were <1 day for the ponds B4 and B5, where PO4 concentrations were higher (1.4 and 1.8 mg/l), and 3 and 3.4 days for ponds A3 and C2, respectively, where ortho-phosphate concentrations were lower (<0.1 mg/l). Particle residence times thus showed an inverse relationship with the concentration of ortho-phosphate, the limiting nutrient in fresh water systems. The same relationship to the concentration of ortho-phosphate or any of the other nutrient elements was not evident for the residence times of dissolved 234Th, which ranged between 0.1 and 2 days. This can be attributed to higher concentrations of dissolved and particulate ligands with greater binding potential for actinides such as four-valent Th and Pu in ponds with higher ortho-phosphate concentrations. Regardless of actual ortho-phosphate concentration, however, at water residence (holding) times of 1 month in these ponds, particles and associated actinides would be expected to be completely removed from the pond water to sediments. PMID:15261419

  12. Inverse dependency of particle residence times in ponds to the concentration of phosphate, the limiting nutrient.

    PubMed

    Roberts, Kimberly A; Santschi, Peter H

    2004-01-01

    234Th, a commonly used short-lived particle-reactive tracer in marine systems, was measured in three different holding pond series at the Rocky Flats Environmental Technology Site (RFETS), Colorado, along with its parent nuclide 238U, to determine steady-state residence times of particle-reactive actinides such as Pu, and of particles. Series B ponds, which received industrial effluent that includes ortho-phosphate (PO4) and actinides, differed from series A and C ponds, which did not. This difference was also evident in the calculated particle residence times, which were <1 day for the ponds B4 and B5, where PO4 concentrations were higher (1.4 and 1.8 mg/l), and 3 and 3.4 days for ponds A3 and C2, respectively, where ortho-phosphate concentrations were lower (<0.1 mg/l). Particle residence times thus showed an inverse relationship with the concentration of ortho-phosphate, the limiting nutrient in fresh water systems. The same relationship to the concentration of ortho-phosphate or any of the other nutrient elements was not evident for the residence times of dissolved 234Th, which ranged between 0.1 and 2 days. This can be attributed to higher concentrations of dissolved and particulate ligands with greater binding potential for actinides such as four-valent Th and Pu in ponds with higher ortho-phosphate concentrations. Regardless of actual ortho-phosphate concentration, however, at water residence (holding) times of 1 month in these ponds, particles and associated actinides would be expected to be completely removed from the pond water to sediments.

  13. Selective Concentration of Ultra-trace Acetone in the Air by Cryogenic Temperature Programmed Desorption (cryo-TPD).

    PubMed

    Suzuki, Taku T; Sakaguchi, Isao

    2016-01-01

    A gas analytical technique with compact size, low cost, sufficient sensitivity, and excellent reproducibility is required in many fields including exhaled breath analysis for medical monitoring. In the present study, we examined selective acetone concentration by quench condensation at cryogenic temperature followed by temperature programmed desorption (cryogenic temperature programmed desorption (cryo-TPD)) for possible applications to breath analysis for medical monitoring. The essence of cryo-TPD is rough mass selection by thermal desorption followed by quantification of certain species using mass spectrometry. The performance of cryo-TPD was investigated in the acetone concentration range below 1 × 10(-6) volume fraction (1 ppmv). It was found that acetone is selectively quench-condensed on a tungsten substrate at 50 K without the major components of air, such as N2 and O2. The concentrated acetone gas was obtained by the following thermal desorption at around 151 K. Under conditions of condensation for 1 min and pressure of 1 × 10(-2) Pa, the lowest limit of detection reached well below 10 × 10(-9) volume fraction (10 ppbv). The relationship between the cetone intensity of cryo-TPD and the acetone concentration in the gas was almost linear in the ppbv range. The separation of acetone and propanal using the fragmentation pattern, which have almost the identical molecular mass, was also demonstrated in the present study. PMID:27682397

  14. Dynamics of carbon dioxide concentrations in the air and its effect on the cognitive ability of school students

    NASA Astrophysics Data System (ADS)

    Sidorin, D. I.

    2015-12-01

    The carbon dioxide (CO2) production intensity by a secondary school student is studied using a nondispersive infrared CO2 logger for different conditions: relaxation, mental stress, and physical stress. CO2 production measured for mental stress is 24% higher than that for relaxation, while CO2 production for physical stress is more than 2.5 times higher than relaxation levels. Dynamics of CO2 concentration in the classroom air is measured for a typical school building. It is shown that even when the classroom is ventilated between classes, CO2 concentration exceeds 2100 parts per million (ppm), which is significantly higher than the recommended limits defined in developed countries. The ability of seventh-grade school students to perform tasks requiring mental concentration is tested under different CO2 concentration conditions (below 1000 ppm and above 2000 ppm). Five-letter word anagrams are used as test tasks. Statistical analysis of the test results revealed a significant reduction in the number of provided correct answers and an increase in the number of errors when CO2 levels exceeded 2000 ppm.

  15. Determination of lead, cations, and anions concentration in indoor and outdoor air at the primary schools in Kuala Lumpur.

    PubMed

    Awang, Normah; Jamaluddin, Farhana

    2014-01-01

    This study was carried out to determine the concentration of lead (Pb), anions, and cations at six primary schools located around Kuala Lumpur. Low volume sampler (MiniVol PM10) was used to collect the suspended particulates in indoor and outdoor air. Results showed that the concentration of Pb in indoor air was in the range of 5.18 ± 1.08 μg/g-7.01 ± 0.08 μg/g. All the concentrations of Pb in indoor air were higher than in outdoor air at all sampling stations. The concentrations of cations and anions were higher in outdoor air than in indoor air. The concentration of Ca(2+) (39.51 ± 5.01 mg/g-65.13 ± 9.42 mg/g) was the highest because the cation existed naturally in soil dusts, while the concentrations of NO3 (-) and SO4 (2-) were higher in outdoor air because there were more sources of exposure for anions in outdoor air, such as highly congested traffic and motor vehicles emissions. In comparison, the concentration of NO3 (-) (29.72 ± 0.31 μg/g-32.00 ± 0.75 μg/g) was slightly higher than SO4 (2-). The concentrations of most of the parameters in this study, such as Mg(2+), Ca(2+), NO3 (-), SO4 (2-), and Pb(2+), were higher in outdoor air than in indoor air at all sampling stations.

  16. Modeling VOC emissions and air concentrations from the Exxon Valdez oil spill

    SciTech Connect

    Hanna, S.R. ); Drivas, P.J. )

    1993-03-01

    During the two-week period following the Exxon Valdez oil spill in March 1989 in Prince William Sound, Alaska, toxic volatile organic compounds (VOCs) evaporated from the surface of the oil spill and were transported and dispersed throughout the region. To estimate the air concentrations of these VOCs, emissions and dispersion modeling was conducted for each hour during the first two weeks of the spill. A multicomponent evaporative emissions model was developed and applied to the oil spill; the model considered the evaporation of 15 specific compounds, including benzene and toluene. Both mass transfer from the surface of the spill and diffusion through the oil layer were considered in the emissions model. Maximum emissions of toluene were calculated to equal about 20,000 kg/hr, or about 5 g/m[sup 2] hr, at a time of eight hours after the initial oil spill. Meteorological data were acquired from sources and used to estimate hourly-averaged wind velocity over the spill. Air concentrations of specific components were calculated using the ATDL area source diffusion model and the Offshore and Coastal Dispersion (OCD) model. Maximum hourly-averaged concentrations were predicted not to exceed 10 ppmv for any compound. 24 refs., 6 figs., 4 tabs.

  17. Air quality modelling : effects of emission reductions on concentrations of particulate matter

    NASA Astrophysics Data System (ADS)

    Girault, L.; Roustan, Y.; Seigneur, C.

    2012-04-01

    Atmospheric particulate matter (PM) has adverse effects on human health. PM acts primarily on respiratory and cardiovascular (due to their small size they can penetrate deep into the lungs), but they are also known effects on the skin. In France, the "Particulate Plan" - developed as part of the second National Environmental Health Plan - aims to reduce by 30% fine PM (noted PM2.5because these particles have an aerodynamic diameter of 2.5 micrometers or less) by 2015. A recent study by Airparif (the organization in charge of monitoring air quality in the Paris region, the Île-de-France) and LSCE (Laboratory of climate and the environmental science, France) has allowed, through a large measurement campaign conducted between 2009 and 2011, to quantify the proportion of PM produced in Île-de-France and those transported from the surrounding areas. The study by numerical modelling of air pollution presented here complements these results by investigating future emission scenarios. The CEREA develops and uses an air quality model which simulates the concentrations of pollutants from an emission inventory, meteorological data and boundary conditions of the area studied. After an evaluation of simulation results for the year 2005, the model is used to assess the effects of various scenarios of reductions in NOx and NH3 emissions on the concentrations of PM2.5in Île-de-France. The effects of the controls on the local pollution and the long-range pollution are considered separately. For each emitted species, three scenarios of emission reductions are identified: an emission reduction at the local level (Île-de-France), a reduction at the regional scale (France) and a reduction at the continental scale (across Europe). In each case, a 15% reduction is applied. The comparison of the results allows us to assess the respective contributions of local emissions and long-range transport to PM2.5 concentrations. For instance, the reduction of NOx emissions in Europe leads to a

  18. Extraordinary acoustic transmission through annuluses in air and its applications in acoustic beam splitter and concentrator.

    PubMed

    Ge, Yong; Sun, Hong-Xiang; Liu, Shu-Sen; Yuan, Shou-Qi; Xia, Jian-Ping; Guan, Yi-Jun; Zhang, Shu-Yi

    2016-08-01

    We report an extraordinary acoustic transmission through two layer annuluses made of metal cylinders in air both numerically and experimentally. The effect arises from the enhancement and reconstruction of the incident source induced by different Mie-resonance modes of the annuluses. The proposed system takes advantages of the consistency in the waveform between the input and output waves, the high amplitude amplification of output waves, and the easy adjustment of structure. More interestingly, we investigate the applications of the extraordinary acoustic transmission in the acoustic beam splitter and acoustic concentrator. Our finding should have an impact on ultrasonic applications. PMID:27587144

  19. Extraordinary acoustic transmission through annuluses in air and its applications in acoustic beam splitter and concentrator

    NASA Astrophysics Data System (ADS)

    Ge, Yong; Sun, Hong-xiang; Liu, Shu-sen; Yuan, Shou-qi; Xia, Jian-ping; Guan, Yi-jun; Zhang, Shu-yi

    2016-08-01

    We report an extraordinary acoustic transmission through two layer annuluses made of metal cylinders in air both numerically and experimentally. The effect arises from the enhancement and reconstruction of the incident source induced by different Mie-resonance modes of the annuluses. The proposed system takes advantages of the consistency in the waveform between the input and output waves, the high amplitude amplification of output waves, and the easy adjustment of structure. More interestingly, we investigate the applications of the extraordinary acoustic transmission in the acoustic beam splitter and acoustic concentrator. Our finding should have an impact on ultrasonic applications.

  20. Implications of Limiting CO2 Concentrations for Land Use and Energy

    SciTech Connect

    Wise, Marshall A.; Calvin, Katherine V.; Thomson, Allison M.; Clarke, Leon E.; Bond-Lamberty, Benjamin; Sands, Ronald D.; Smith, Steven J.; Janetos, Anthony C.; Edmonds, James A.

    2009-05-29

    This paper is the first to simultaneously examine the implications of extending the concept of placing a value on carbon beyond fossil fuel and industrial emissions to all sources, including those associated with land use and land use change. The paper reports a variety of results that have bearing on recent discussions in the literature regarding the role of bioenergy and the indirect emission of carbon through land-use change as well as the burgeoning literature on interactions between bioenergy and crop prices. This paper goes beyond results currently in the literature by using an integrated assessment model to assess energy use and supply, atmospheric composition, land use, and terrestrial carbon in the context of limiting the concentration of atmospheric CO2. We find that when the concept of valuing carbon emissions is extended to all carbon emissions, regardless of origin, that in contrast to a mitigation scenario where only fossil fuel and industrial carbon emissions are valued, deforestation is replaced by afforestation and expanded unmanaged ecosystems; the cost of limiting CO2 concentrations falls; crop prices rise; and human diets are transformed as people shift away from consumption of beef and other carbon-intensive protein sources. The increase in crop prices flows directly from the consideration of land-use change emissions in a comprehensive emissions mitigation program and occurs even in the absence of the use of purpose-grown bioenergy. Finally, we find that the assumed rate of improvement in food and fiber crop productivity (e.g. wheat, rice, corn) has a strong influence on land-use change emissions, making the technology for growing crops potentially as important for limiting atmospheric CO2 concentrations as energy technologies such as CO2 capture and storage.

  1. Soil Redox Chemistry Limitation of Selenium Concentration in Carex Species Sedges

    SciTech Connect

    Bruce J. Mincher; John Mionczynski; Patrick A. Hnilicka

    2007-09-01

    The trace element selenium (Se) is required in the production of enzymes that protect mammalian cells from oxidative damage due to the byproducts of aerobic respiration. Its deficiency in livestock results in the nutritional muscular dystrophy called white muscle disease. This especially affects juveniles in the preweaning period. Symptoms have also been reported in wild herbivores on low-Se forage, and their appearance may be episodic, suggesting temporal variations in Se uptake by plants. Here, we report variations in selenium concentrations in Carex spp. sedges used as forage by bighorn sheep (Ovis canadensis) on summer range in the Wyoming, Wind River Mountains, and correlate those variations with soil conditions that affect the bioavailability of selenium. Variations in available Se are explained based upon the known oxidation/reduction chemistry of the element. It is concluded that water-saturated, alpine soils provide conditions suitable for the reduction of Se to the unavailable, elemental form, limiting its concentration in forage plants.

  2. Variation of POP concentrations in fresh-fallen snow and air on an Alpine glacier (Monte Rosa).

    PubMed

    Finizio, A; Villa, S; Raffaele, F; Vighi, M

    2006-01-01

    To understand better the mechanisms ruling the fate of POPs (persistent organic pollutants) in cold environments, a field campaign sampling fresh-fallen snow and air on an Alpine glacier was carried out during Summer 2003. The concentrations of all analyzed chemicals in fresh-fallen snow show a sharp decrease over time, particularly for the more volatile POPs, confirming the rather limited literature evidence of a rapid decline of such substances from the snowpack and/or ice. Even if the results presented here are preliminary and should be confirmed by further studies, some evidence of the influence of a night/day cycle of temperature on POP deposition and revolatilization mechanisms has been highlighted. Finally, the role of cold condensation and long-range atmospheric transport in the contamination of higher altitudes in this Alpine system has been substantiated, particularly for OC pesticides.

  3. A theoretical study of limit cycle oscillations of plenum air cushions

    NASA Astrophysics Data System (ADS)

    Hinchey, M. J.; Sullivan, P. A.

    1981-11-01

    Air cushion vehicles (ACV) are prone to the occurrence of dynamic instabilities which frequently appear as stable finite amplitude oscillations. The aim of this work is to ascertain if the non-linearities characteristics of ACV dynamics generate limit cycle oscillations for cushion systems operating at conditions for which a linear theory predicts instability. The types of non-linearity that can occur are discussed, and an analysis is presented for a single cell flexible skirted plenum chamber constrained to move in pure heave only. Two cushion feed cases are considered: a plenum box supply and a duct. The results obtained by a Galerkin/describing function analysis are compared with those generated by a full numerical simulation. For the plenum box supply system, it is shown that the limit cycles can be suppressed by using a piston to introduce high frequency small amplitude volume oscillations into the plenum chamber.

  4. The influence of air-suspended particulate concentration on the incidence of suicide attempts and exacerbation of schizophrenia

    NASA Astrophysics Data System (ADS)

    Yackerson, Naomy S.; Zilberman, Arkadi; Todder, Doron; Kaplan, Zeev

    2014-01-01

    The main objective of this study was to evaluate the role of the concentration of solid air-suspended particles (SSP) in the incidence of mental disorders. The study is based on 1,871 cases, registered in the Beer-Sheva Mental Health Center (BS-MHC) at Ben-Gurion University (Israel) during a 16-month period from 2001 to 2002; 1,445 persons were hospitalized due to exacerbation of schizophrenia (ICD-10: F20-F29) and 426 after committing a suicide attempt using a variety of means as coded in the ICD-10 (ICD-10: X60-X84). Pearson and Spearman test correlations were used; the statistical significance was tested at p < 0.1. A significant correlation between variations of SSP number concentration ( N C ) during eastern desert wind during early morning hours and number of suicide attempts, N SU , was found ( ρ > 0.3, p < 0.05), whereas correlation between N C and N SU during western air streams (sea breeze) was not observed ( p > 0.2). A trend towards positive correlation ( ρ > 0.2, p < 0.1) between the N C and number of persons with exacerbation of schizophrenia as manifested in psychotic attack ( N PS ) in periods with dominant eastern winds (4-9 am, local time) has been observed, while in the afternoon and evening hours (1-8 pm local time) with dominant western winds, N C and N PS are not correlated (p > 0.1). Obviously, concentration of SSP is not the one and only parameter of air pollution state determining meteorological-biological impact, involving incidence of mental disorders, although its role can scarcely be overstated. However, since it is one of the simplest measured parameters, it could be widely used and helpful in the daily struggle for human life comfort in semi-arid areas as well as urban and industrial surroundings, where air pollution reaches crucial values. This study may permit determination of the limits for different external factors, which do not overcome threshold values (without provoking avalanche situations), to single out the group of

  5. Mixing layer height measurements determines influence of meteorology on air pollutant concentrations in urban area

    NASA Astrophysics Data System (ADS)

    Schäfer, Klaus; Blumenstock, Thomas; Bonn, Boris; Gerwig, Holger; Hase, Frank; Münkel, Christoph; Nothard, Rainer; von Schneidemesser, Erika

    2015-10-01

    Mixing layer height (MLH) is a key parameter to determine the influence of meteorological parameters upon air pollutants such as trace gas species and particulate concentrations near the surface. Meteorology, and MLH as a key parameter, affect the budget of emission source strengths, deposition, and accumulation. However, greater possibilities for the application of MLH data have been identified in recent years. Here, the results of measurements in Berlin in 2014 are shown and discussed. The concentrations of NO, NO2, O3, CO, PM1, PM2.5, PM10 and about 70 volatile organic compounds (anthropogenic and biogenic of origin) as well as particle size distributions and contributions of SOA and soot species to PM were measured at the urban background station of the Berlin air quality network (BLUME) in Nansenstr./Framstr., Berlin-Neukölln. A Vaisala ceilometer CL51, which is a commercial mini-lidar system, was applied at that site to detect the layers of the lower atmosphere in real time. Special software for these ceilometers with MATLAB provided routine retrievals of MLH from vertical profiles of laser backscatter data. Five portable Bruker EM27/SUN FTIR spectrometers were set up around Berlin to detect column averaged abundances of CO2 and CH4 by solar absorption spectrometry. Correlation analyses were used to show the coupling of temporal variations of trace gas compounds and PM with MLH. Significant influences of MLH upon NO, NO2, PM10, PM2.5, PM1 and toluene (marker for traffic emissions) concentrations as well as particle number concentrations in the size modes 70 - 100 nm, 100 - 200 nm and 200 - 500 nm on the basis of averaged diurnal courses were found. Further, MLH was taken as important auxiliary information about the development of the boundary layer during each day of observations, which was required for the proper estimation of CO2 and CH4 source strengths from Berlin on the basis of atmospheric column density measurements.

  6. Soil Surface Carbon Dioxide Fluxes and Carbon Dioxide Concentrations in Soil Air

    NASA Astrophysics Data System (ADS)

    Arkebauer, T. J.; Billesbach, D.

    2006-12-01

    We have been monitoring soil surface CO2 fluxes at three AmeriFlux sites in eastern Nebraska for several years. Recently, we have installed soil CO2 sensors at the rainfed soybean site in order to obtain profiles of CO2 concentrations in soil air (to 0.8 m depth). Supporting data include profiles of soil water content and soil temperature, aboveground biomass, leaf area index and precipitation. Soil surface fluxes had been rather small for much of the 2006 growing season (e.g., midday values of about 5 umol/m2/s) due, in large part, to the very dry conditions in eastern Nebraska and the consequent low soil water contents. However, copious rainfall in August raised soil water contents to field capacity throughout the profile. Soil air CO2 concentrations during this period also increased and reached peaks near 10% (at 0.4 and 0.8 m depth). Through analyses of relationships between surface CO2 flux and profiles of soil parameters we seek to identify biophysical factors responsible for controlling surface fluxes as well as to begin to quantify sources and sinks of CO2 within the soil profile (e.g., plant-related production of CO2 due to root exudation and respiration). The influence of precipitation events on CO2 profiles and fluxes is of particular interest.

  7. Portable Cathode-Air Vapor-Feed Electrochemical Medical Oxygen Concentrator (OC)

    NASA Technical Reports Server (NTRS)

    Balasubramanian, Ashwin

    2015-01-01

    Missions on the International Space Station and future space exploration will present significant challenges to crew health care capabilities, particularly in the efficient utilization of onboard oxygen resources. Exploration vehicles will require lightweight, compact, and portable oxygen concentrators that can provide medical-grade oxygen from the ambient cabin air. Current pressure-swing adsorption OCs are heavy and bulky, require significant start-up periods, operate in narrow temperature ranges, and require a liquid water feed. Lynntech, Inc., has developed an electrochemical OC that operates with a cathode-air vapor feed, eliminating the need for a bulky onboard water supply. Lynntech's OC is smaller and lighter than conventional pressure-swing OCs, is capable of instant start-up, and operates over a temperature range of 5-80 C. Accomplished through a unique nanocomposite proton exchange membrane and catalyst technology, the unit delivers 4 standard liters per minute of humidified oxygen at 60 percent concentration. The technology enables both ambient-pressure operating devices for portable applications and pressurized (up to 3,600 psi) OC devices for stationary applications.

  8. 40 CFR 60.3066 - What are the emission limitations for air curtain incinerators that burn only wood waste, clean...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... air curtain incinerators that burn only wood waste, clean lumber, and yard waste? 60.3066 Section 60... Curtain Incinerators That Burn Only Wood Waste, Clean Lumber, and Yard Waste § 60.3066 What are the emission limitations for air curtain incinerators that burn only wood waste, clean lumber, and yard...

  9. 40 CFR 60.3066 - What are the emission limitations for air curtain incinerators that burn only wood waste, clean...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... air curtain incinerators that burn only wood waste, clean lumber, and yard waste? 60.3066 Section 60... Curtain Incinerators That Burn Only Wood Waste, Clean Lumber, and Yard Waste § 60.3066 What are the emission limitations for air curtain incinerators that burn only wood waste, clean lumber, and yard...

  10. 40 CFR 60.2971 - What are the emission limitations for air curtain incinerators that burn only wood waste, clean...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... air curtain incinerators that burn only wood waste, clean lumber, and yard waste? 60.2971 Section 60... Incinerators That Burn Only Wood Waste, Clean Lumber, and Yard Waste § 60.2971 What are the emission limitations for air curtain incinerators that burn only wood waste, clean lumber, and yard waste? (a)...

  11. 40 CFR 60.3066 - What are the emission limitations for air curtain incinerators that burn only wood waste, clean...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... air curtain incinerators that burn only wood waste, clean lumber, and yard waste? 60.3066 Section 60... Curtain Incinerators That Burn Only Wood Waste, Clean Lumber, and Yard Waste § 60.3066 What are the emission limitations for air curtain incinerators that burn only wood waste, clean lumber, and yard...

  12. 40 CFR 62.15375 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Waste § 62.15375 What are the emission limits for air curtain incinerators that burn 100 percent yard waste? If your air curtain incinerator combusts 100 percent yard waste, you must meet only the emission... curtain incinerators that burn 100 percent yard waste? 62.15375 Section 62.15375 Protection of...

  13. 40 CFR 60.2971 - What are the emission limitations for air curtain incinerators that burn only wood waste, clean...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... air curtain incinerators that burn only wood waste, clean lumber, and yard waste? 60.2971 Section 60... Incinerators That Burn Only Wood Waste, Clean Lumber, and Yard Waste § 60.2971 What are the emission limitations for air curtain incinerators that burn only wood waste, clean lumber, and yard waste? (a)...

  14. 40 CFR 60.3066 - What are the emission limitations for air curtain incinerators that burn only wood waste, clean...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... air curtain incinerators that burn only wood waste, clean lumber, and yard waste? 60.3066 Section 60... Curtain Incinerators That Burn Only Wood Waste, Clean Lumber, and Yard Waste § 60.3066 What are the emission limitations for air curtain incinerators that burn only wood waste, clean lumber, and yard...

  15. 40 CFR 60.1920 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... curtain incinerators that burn 100 percent yard waste? 60.1920 Section 60.1920 Protection of Environment... or Before August 30, 1999 Model Rule-Air Curtain Incinerators That Burn 100 Percent Yard Waste § 60.1920 What are the emission limits for air curtain incinerators that burn 100 percent yard waste?...

  16. 40 CFR 60.3066 - What are the emission limitations for air curtain incinerators that burn only wood waste, clean...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... air curtain incinerators that burn only wood waste, clean lumber, and yard waste? 60.3066 Section 60... Curtain Incinerators That Burn Only Wood Waste, Clean Lumber, and Yard Waste § 60.3066 What are the emission limitations for air curtain incinerators that burn only wood waste, clean lumber, and yard...

  17. 40 CFR 60.2971 - What are the emission limitations for air curtain incinerators that burn only wood waste, clean...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... air curtain incinerators that burn only wood waste, clean lumber, and yard waste? 60.2971 Section 60... Incinerators That Burn Only Wood Waste, Clean Lumber, and Yard Waste § 60.2971 What are the emission limitations for air curtain incinerators that burn only wood waste, clean lumber, and yard waste? (a)...

  18. 40 CFR 62.15375 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... curtain incinerators that burn 100 percent yard waste? 62.15375 Section 62.15375 Protection of Environment... Combustion Units Constructed on or Before August 30, 1999 Air Curtain Incinerators That Burn 100 Percent Yard Waste § 62.15375 What are the emission limits for air curtain incinerators that burn 100 percent...

  19. 40 CFR 60.1920 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... curtain incinerators that burn 100 percent yard waste? 60.1920 Section 60.1920 Protection of Environment... or Before August 30, 1999 Model Rule-Air Curtain Incinerators That Burn 100 Percent Yard Waste § 60.1920 What are the emission limits for air curtain incinerators that burn 100 percent yard waste?...

  20. 40 CFR 62.15375 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... curtain incinerators that burn 100 percent yard waste? 62.15375 Section 62.15375 Protection of Environment... Combustion Units Constructed on or Before August 30, 1999 Air Curtain Incinerators That Burn 100 Percent Yard Waste § 62.15375 What are the emission limits for air curtain incinerators that burn 100 percent...

  1. 40 CFR 62.15375 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... curtain incinerators that burn 100 percent yard waste? 62.15375 Section 62.15375 Protection of Environment... Combustion Units Constructed on or Before August 30, 1999 Air Curtain Incinerators That Burn 100 Percent Yard Waste § 62.15375 What are the emission limits for air curtain incinerators that burn 100 percent...

  2. 40 CFR 60.1920 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... curtain incinerators that burn 100 percent yard waste? 60.1920 Section 60.1920 Protection of Environment... or Before August 30, 1999 Model Rule-Air Curtain Incinerators That Burn 100 Percent Yard Waste § 60.1920 What are the emission limits for air curtain incinerators that burn 100 percent yard waste?...

  3. 40 CFR 62.15375 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... curtain incinerators that burn 100 percent yard waste? 62.15375 Section 62.15375 Protection of Environment... Combustion Units Constructed on or Before August 30, 1999 Air Curtain Incinerators That Burn 100 Percent Yard Waste § 62.15375 What are the emission limits for air curtain incinerators that burn 100 percent...

  4. 40 CFR 60.1920 - What are the emission limits for air curtain incinerators that burn 100 percent yard waste?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... curtain incinerators that burn 100 percent yard waste? 60.1920 Section 60.1920 Protection of Environment... or Before August 30, 1999 Model Rule-Air Curtain Incinerators That Burn 100 Percent Yard Waste § 60.1920 What are the emission limits for air curtain incinerators that burn 100 percent yard waste?...

  5. Concentration and determinants of molds and allergens in indoor air and house dust of French dwellings.

    PubMed

    Dallongeville, Arnaud; Le Cann, Pierre; Zmirou-Navier, Denis; Chevrier, Cécile; Costet, Nathalie; Annesi-Maesano, Isabella; Blanchard, Olivier

    2015-12-01

    Molds and allergens are common indoor biocontaminants. The aims of this study were to assess the concentrations of common molds in indoor air and floor dust and the concentrations of house dust mite, cat and dog allergens in mattress dust in French dwellings, and to assess predictors of these concentrations. A sample of 150 houses in Brittany (western France) was investigated. Airborne Cladosporium and Penicillium were detected in more than 90% of the dwellings, Aspergillus in 46% and Alternaria in only 6% of the housings. Regarding floor dust samples, Cladosporium and Penicillium were detected in 92 and 80% of the housings respectively, Aspergillus in 49% and Alternaria in 14%. House dust mite allergens Der p1 and Der f1 were detected in 90% and 77% of the mattress dust samples respectively and Can f1 and Fel d1 in 37% and 89% of the homes. Airborne and dustborne mold concentrations, although not statistically correlated (except for Aspergillus) shared most of their predictors. Multivariate linear models for mold levels, explaining up to 62% of the variability, showed an influence of the season, of the age of the dwelling, of aeration habits, presence of pets, smoking, signals of dampness, temperature and relative humidity. Allergens in the dust of the mattress were strongly related to the presence of pets and cleaning practices of bedsheets, these factors accounting for 60% of the variability. This study highlights ubiquitous contamination by molds and underlines complex interaction between outdoor and indoor sources and factors. PMID:26094801

  6. LINKING AIR TOXIC CONCENTRATIONS FROM CMAQ TO THE HAPEM5 EXPOSURE MODEL AT NEIGHORHOOD SCALES FOR THE PHILADELPHIA AREA

    EPA Science Inventory

    This paper provides a preliminary demonstration of the EPA neighborhood scale modeling paradigm for air toxics by linking concentration from the Community Multi-scale Air Quality (CMAQ) modeling system to the fifth version of the Hazardous Pollutant Exposure Model (HAPEM5). For ...

  7. Effect of central ventilation and air conditioner system on the concentration and health risk from airborne polycyclic aromatic hydrocarbons.

    PubMed

    Lv, Jinze; Zhu, Lizhong

    2013-03-01

    Central ventilation and air conditioner systems are widely utilized nowadays in public places for air exchange and temperature control, which significantly influences the transfer of pollutants between indoors and outdoors. To study the effect of central ventilation and air conditioner systems on the concentration and health risk from airborne pollutants, a spatial and temporal survey was carried out using polycyclic aromatic hydrocarbons (PAHs) as agent pollutants. During the period when the central ventilation system operated without air conditioning (AC-off period), concentrations of 2-4 ring PAHs in the model supermarket were dominated by outdoor levels, due to the good linearity between indoor air and outdoor air (r(p) > 0.769, p < 0.05), and the slopes (1.2-4.54) indicated that ventilating like the model supermarket increased the potential health risks from low molecular weight PAHs. During the period when the central ventilation and air conditioner systems were working simultaneously (AC-on period), although the total levels of PAHs were increased, the concentrations and percentage of the particulate PAHs indoors declined significantly. The BaP equivalency (BaPeq) concentration indicated that utilization of air conditioning reduced the health risks from PAHs in the model supermarket. PMID:23923426

  8. Concentrations and potential health risks of methyl tertiary-butyl ether (MTBE) in air and drinking water from Nanning, South China.

    PubMed

    Zhang, Li'e; Qin, Jian; Zhang, Zhiyong; Li, Qin; Huang, Jiongli; Peng, Xiaowu; Qing, Li; Liang, Guiqiang; Liang, Linhan; Huang, Yuman; Yang, Xiaobo; Zou, Yunfeng

    2016-01-15

    Levels of methyl tertiary-butyl ether (MTBE) in occupational air, ambient air, and drinking water in Nanning, South China, were investigated, and then their potential health risks to occupational workers and the general public were evaluated. Results show that the MTBE concentration in occupational air from 13 service stations was significantly higher than that in ambient air from residential areas (p<0.0001); both are far lower than the threshold limit value-time weighted average of MTBE regulated in the United States (US). The drinking water samples from household taps yielded detectable MTBE in the range of 0.04-0.33 μg/L, which is below the US drinking water standard of 20-40 μg/L. The non-carcinogenic risk of MTBE from air inhalation may be negligible because the calculated hazard quotient was less than 1. The mean MTBE lifetime cancer risk was within the acceptable limit of 1 × 10(-6) to 1 × 10(-4), but the lifetime cancer risk of refueling workers in the urban service station at the 95th percentile slightly exceeded the maximum acceptable carcinogen risk (1 × 10(-4)), indicating the potential carcinogenic health effects on the population highly exposed to MTBE in this region. The hazard index and carcinogenic risk of MTBE in drinking water were significantly lower than the safe limit of US Environmental Protection Agency, suggesting that drinking water unlikely poses significant health risks to the residents in Nanning.

  9. Influence of eutrophication on air-water exchange, vertical fluxes, and phytoplankton concentrations of persistent organic pollutants

    SciTech Connect

    Dachs, J.; Eisenreich, S.J.; Hoff, R.M.

    2000-03-15

    The influence of eutrophication on the biogeochemical cycles of persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) is largely unknown. In this paper, the application of a dynamic air-water-phytoplankton exchange model to Lake Ontario is used as a framework to study the influence of eutrophication on air-water exchange, vertical fluxes, and phytoplankton concentrations of POPs. The results of these simulations demonstrate that air-water exchange controls phytoplankton concentrations in remote aquatic environments with little influence from land-based sources of pollutants and supports levels in even historically contaminated systems. Furthermore, eutrophication or high biomass leads to a disequilibrium between the gas and dissolved phase, enhanced air-water exchange, and vertical sinking fluxes of PCBs. Increasing biomass also depletes the water concentrations leading to lower than equilibrium PCB concentrations in phytoplankton. Implications to future trends in PCB pollution in Lake Ontario are also discussed.

  10. Correlation between the limiting pH of metal ion solubility and total metal concentration

    SciTech Connect

    Apak, R.; Hizal, J.; Ustaer, C.

    1999-03-15

    As an alternative to species distribution diagrams (pM vs pH curves in aqueous solution) drawn for a fixed total metal concentration, this work has developed simple linear models for correlating the limiting pH of metal ion solubility -- in equilibrium with the least soluble amorphous metal hydroxide solid phase -- to the total metal concentration. Thus adsorptive metal removal processes in complex systems can be better designed once the limiting pH of heavy metal solubility (i.e., pH{sup *}) in such a complex environment can be envisaged by simple linear equations. pH{sup *} vs pM{sub t} (M{sub t} = total metal concentration that can exist in aqueous solution in equilibrium with M(OH){sub 2(s)}) linear curves for uranyl-hydroxide, uranyl-carbonate-hydroxide, and mercuric-chloride-hydroxide simple and mixed-ligand systems and cupric-carbonate-hydroxide complexes in equilibrium with mixed hydroxide solid phases may enable the experimental chemist to distinguish true adsorption (e.g., onto hydrous oxide sorbents) from bulk precipitation removal of the metal and to interpret some anomalous metal fixation data -- usually attributed to pure adsorption in the literature -- with precipitation if the pM{sub t} at the studied pH is lower than that tolerated by pH{sup *} vs pM{sub t} curves. This easily predictable pH{sup *} corresponding to a given pM{sub t} may aid the design of desorptive mobilization experiments for certain metals as well as their adsorptive removal with the purpose of simulating metal adsorption and desorption cycles in real complex environments with changing groundwater pH.

  11. 14 CFR 93.219 - Allocation of slots for essential air service operations and applicable limitations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... SPECIAL AIR TRAFFIC RULES Allocation of Commuter and Air Carrier IFR Operations at High Density Traffic... or from a High Density Traffic Airport under the Department of Transportation's Essential Air...

  12. 14 CFR 93.219 - Allocation of slots for essential air service operations and applicable limitations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... SPECIAL AIR TRAFFIC RULES Allocation of Commuter and Air Carrier IFR Operations at High Density Traffic... or from a High Density Traffic Airport under the Department of Transportation's Essential Air...

  13. 14 CFR 93.219 - Allocation of slots for essential air service operations and applicable limitations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... SPECIAL AIR TRAFFIC RULES Allocation of Commuter and Air Carrier IFR Operations at High Density Traffic... or from a High Density Traffic Airport under the Department of Transportation's Essential Air...

  14. 14 CFR 93.219 - Allocation of slots for essential air service operations and applicable limitations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... SPECIAL AIR TRAFFIC RULES Allocation of Commuter and Air Carrier IFR Operations at High Density Traffic... or from a High Density Traffic Airport under the Department of Transportation's Essential Air...

  15. 14 CFR 93.219 - Allocation of slots for essential air service operations and applicable limitations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... SPECIAL AIR TRAFFIC RULES Allocation of Commuter and Air Carrier IFR Operations at High Density Traffic... or from a High Density Traffic Airport under the Department of Transportation's Essential Air...

  16. Concentrated ambient air particles induce vasoconstriction of small pulmonary arteries in rats.

    PubMed Central

    Batalha, Joao R F; Saldiva, Paulo H N; Clarke, Robert W; Coull, Brent A; Stearns, Rebecca C; Lawrence, Joy; Murthy, G G Krishna; Koutrakis, Petros; Godleski, John J

    2002-01-01

    The objective of this study was to determine whether short-term exposures to concentrated ambient particles (CAPs) alter the morphology of small pulmonary arteries in normal rats and rats with chronic bronchitis (CB). Sprague-Dawley male rats were exposed to CAPs, using the Harvard Ambient Particle Concentrator, or to particle-free air (sham) under identical conditions during 3 consecutive days (5 hr/day) in six experimental sets. CB was induced by exposure to 276 +/- 9 ppm of sulfur dioxide (5 hr/day, 5 days/week, 6 weeks). Physicochemical characterization of CAPs included measurements of particle mass, size distribution, and composition. Rats were sacrificed 24 hr after the last CAPs exposure. Histologic slides were prepared from random sections of lung lobes and coded for blinded analysis. The lumen/wall area (L/W) ratio was determined morphometrically on transverse sections of small pulmonary arteries. When all animal data (normal and CB) were analyzed together, the L/W ratios decreased as concentrations of fine particle mass, silicon, lead, sulfate, elemental carbon, and organic carbon increased. In separate univariate analyses of animal data, the association for sulfate was significant only in normal rats, whereas silicon was significantly associated in both CB and normal rats. In multivariate analyses including all particle factors, the association with silicon remained significant. Our results indicate that short-term CAPs exposures (median, 182.75 micro g/m3; range, 73.50-733.00 micro g/m3) can induce vasoconstriction of small pulmonary arteries in normal and CB rats. This effect was correlated with specific particle components and suggests that the pulmonary vasculature might be an important target for ambient air particle toxicity. PMID:12460797

  17. Diagnostic significance of nitric oxide concentrations in exhaled air from the airways in allergic rhinitis patients

    PubMed Central

    Krzych-Fałta, Edyta; Samoliński, Bolesław K; Zalewska, Marta

    2016-01-01

    Introduction The effect of nitric oxide (NO) on the human body is very important due its physiological regulation of the following functions of airways: modulation of ciliary movement and maintenance of sterility in sinuses. Aim To evaluate the diagnostic significance of NO concentrations in exhaled air from the upper and lower airways in patients diagnosed with allergic rhinitis (AR). Material and methods The subjects included in the study were a group of 30 people diagnosed with sensitivity to environmental allergens and a control group consisting of 30 healthy subjects. The measurement of NO in the air exhaled from the lower and upper airways was performed using an on-line method by means of Restricted Exhaled Breath (REB), as well as using the measurement procedure (chemiluminescence) set out in the guidelines prepared in 2005 by the American Thoracic Society and the European Respiratory Society. Results In the late phase of the allergic reaction, higher values of the level of exhaled NO concentration from the lower airways were observed in the groups of subjects up to the threshold values of 25.17 ppb in the group of subjects with year-round allergic rhinitis and 21.78 ppb in the group with diagnosed seasonal allergic rhinitis. The difference in the concentration of NO exhaled from the lungs between the test group and the control group in the 4th h of the test was statistically significant (p = 0.045). Conclusions Exhaled NO should be considered as a marker of airway inflammation. It plays an important role in the differential diagnosis of allergy. PMID:27279816

  18. Opposed Jet Burner Extinction Limits: Simple Mixed Hydrocarbon Scramjet Fuels vs Air

    NASA Technical Reports Server (NTRS)

    Pellett, Gerald L.; Vaden, Sarah N.; Wilson, Lloyd G.

    2007-01-01

    Opposed Jet Burner tools have been used extensively by the authors to measure Flame Strength (FS) of laminar non-premixed H2 air and simple hydrocarbon (HC) air counterflow diffusion flames at 1-atm. FS represents a strain-induced extinction limit based on air jet velocity. This paper follows AIAA-2006-5223, and provides new HC air FSs for global testing of chemical kinetics, and for characterizing idealized flameholding potentials during early scramjet-like combustion. Previous FS data included six HCs, pure and N2-diluted; and three HC-diluted H2 fuels, where FS decayed very nonlinearly as HC was added to H2, due to H-atom scavenging. This study presents FSs on mixtures of (candidate surrogate) HCs, some with very high FS ethylene. Included are four binary gaseous systems at 300 K, and a hot ternary system at approx. 600 K. The binaries are methane + ethylene, ethane + ethylene, methane + ethane, and methane + propylene. The first three also form two ternary systems. The hot ternary includes both 10.8 and 21.3 mole % vaporized n-heptane and full ranges of methane + ethylene. Normalized FS data provide accurate means of (1) validating, globally, chemical kinetics for extinction of non-premixed flames, and (2) estimating (scaling by HC) the loss of incipient flameholding in scramjet combustors. The n-heptane is part of a proposed baseline simulant (10 mole % with 30% methane + 60% ethylene) that mimics the ignition of endothermically cracked JP-7 like kerosene fuel, as suggested by Colket and Spadaccini in 2001 in their shock tube Scramjet Fuels Autoignition Study. Presently, we use FS to gauge idealized flameholding, and define HC surrogates. First, FS was characterized for hot nheptane + methane + ethylene; then a hot 36 mole % methane + 64% ethylene surrogate was defined that mimics FS of the baseline simulant system. A similar hot ethane + ethylene surrogate can also be defined, but it has lower vapor pressure at 300 K, and thus exhibits reduced gaseous

  19. Analysis of radionuclide concentration in air released through the stack of a radiopharmaceutical production facility based on a medical cyclotron

    NASA Astrophysics Data System (ADS)

    Giardina, M.; Tomarchio, E.; Greco, D.

    2015-11-01

    Positron emitting radionuclides are increasingly used in medical diagnostics and the number of radiopharmaceutical production facilities have been estimated to be growing worldwide. During the process of production and/or patient administration of radiopharmaceuticals, an amount of these radionuclides might become airborne and escape into the environment. Therefore, the analysis of radionuclide concentration in the air released to the stack is a very important issue to evaluate the dose to the population living around the plant. To this end, sampling and measurement of radionuclide concentration in air released through the stack of a Nuclear Medicine Center (NMC), provided with a cyclotron for radiopharmaceuticals production, must be routinely carried out with an automatic measurement system. In this work is presented the air monitoring system realized at "San Gaetano" NMC at Bagheria (Italy) besides the analysis of the recorded stack relesead air concentration data. Sampling of air was carried out continuously and gamma-ray spectrometric measurement are made on-line and for a short time by using a shielded Marinelli beaker filled with sampled air and a gamma detector. The use of this system allows to have 1440 values of air concentration per day from 2002, year of the start of operation with the cyclotron. Therefore, the concentration values are very many and an analysis software is needed to determine the dose to the population. A comparison with the results of a simulation code based on a Gaussian Plume air dispersion modelling allow us to confirm the no-radiological significance of the stack effluent releases in terms of dose to population and to evaluate possible improvements in the plant devices to reduce the air concentration at stack.

  20. Effect of ceramic membrane channel diameter on limiting retentate protein concentration during skim milk microfiltration.

    PubMed

    Adams, Michael C; Barbano, David M

    2016-01-01

    Our objective was to determine the effect of retentate flow channel diameter (4 or 6mm) of nongraded permeability 100-nm pore size ceramic membranes operated in nonuniform transmembrane pressure mode on the limiting retentate protein concentration (LRPC) while microfiltering (MF) skim milk at a temperature of 50°C, a flux of 55 kg · m(-2) · h(-1), and an average cross-flow velocity of 7 m · s(-1). At the above conditions, the retentate true protein concentration was incrementally increased from 7 to 11.5%. When temperature, flux, and average cross-flow velocity were controlled, ceramic membrane retentate flow channel diameter did not affect the LRPC. This indicates that LRPC is not a function of the Reynolds number. Computational fluid dynamics data, which indicated that both membranes had similar radial velocity profiles within their retentate flow channels, supported this finding. Membranes with 6-mm flow channels can be operated at a lower pressure decrease from membrane inlet to membrane outlet (ΔP) or at a higher cross-flow velocity, depending on which is controlled, than membranes with 4-mm flow channels. This implies that 6-mm membranes could achieve a higher LRPC than 4-mm membranes at the same ΔP due to an increase in cross-flow velocity. In theory, the higher LRPC of the 6-mm membranes could facilitate 95% serum protein removal in 2 MF stages with diafiltration between stages if no serum protein were rejected by the membrane. At the same flux, retentate protein concentration, and average cross-flow velocity, 4-mm membranes require 21% more energy to remove a given amount of permeate than 6-mm membranes, despite the lower surface area of the 6-mm membranes. Equations to predict skim milk MF retentate viscosity as a function of protein concentration and temperature are provided. Retentate viscosity, retentate recirculation pump frequency required to maintain a given cross-flow velocity at a given retentate viscosity, and retentate protein

  1. MTBE concentrations in ambient air in the vicinity of service stations

    NASA Astrophysics Data System (ADS)

    Vainiotalo, Sinikka; Peltonen, Yrjö; Pfäffli, Pirkko

    Ambient air concentrations of methyl tertiary-butyl ether (MTBE) were monitored in the vicinity of two self-service stations in May-June and October, 1995. These stations (one urban and one roadside) were located in southwestern Finland and were equipped with "stage I" vapour recovery systems. All the gasoline blends dispensed during the study (95, 98 and 99 RON) contained 11% MTBE. The measurements were carried out 24 h day -1 at stationary sampling points located at the four main compass points on the service station perimeter (about 50 m from the centre of the forecourt). The air samples were collected in charcoal tubes and analysed in laboratory by gas chromatography using mass-selective detection. The concentrations in individual samples ranged from 0.5 to 121 μg m -3, and the highest daily concentrations were usually obtained at the downwind sampling points. The arithmetic mean concentrations for each of the four-day sampling periods were: 7.5 μg m -3 (station 1/May-June), 4.1 μg/m 3 (station 1/October), 12.4 μg m -3 (station 2/June) and 14.1 μg m -3 (station 2/October). The mean concentrations measured in the centre of the pump island (only daytime sampling) ranged from 247 to 1347 μg m -3. The levels of MTBE are station-specific and dependent on many factors, such as volumes of gasolines sold, wind speed, exhaust emissions from passing traffic, and deliveries of gasoline to the station. The mean wind speeds were between 0.7 and 1.5 m s -1, and the temperatures were above 22°C in summer and about 10°C in October. The volume of gasoline sold at the urban service station, station 2, was twice that at the roadside service station, station 1. There was one road with high traffic density adjacent to station 1 and two such roads at station 2. Gasoline was delivered twice to station 1 and 3 times to station 2 during the study.

  2. The concentration-response relation between air pollution and daily deaths.

    PubMed Central

    Schwartz, J; Ballester, F; Saez, M; Pérez-Hoyos, S; Bellido, J; Cambra, K; Arribas, F; Cañada, A; Pérez-Boillos, M J; Sunyer, J

    2001-01-01

    Studies on three continents have reported associations between various measures of airborne particles and daily deaths. Sulfur dioxide has also been associated with daily deaths, particularly in Europe. Questions remain about the shape of those associations, particularly whether there are thresholds at low levels. We examined the association of daily concentrations of black smoke and SO(2) with daily deaths in eight Spanish cities (Barcelona, Bilbao, Castellón, Gijón, Oviedo, Valencia, Vitoria, and Zaragoza) with different climates and different environmental and social characteristics. We used nonparametric smoothing to estimate the shape of the concentration-response curve in each city and combined those results using a metasmoothing technique developed by Schwartz and Zanobetti. We extended their method to incorporate random variance components. Black smoke had a nearly linear association with daily deaths, with no evidence of a threshold. A 10 microg/m(3) increase in black smoke was associated with a 0.88% increase in daily deaths (95% confidence interval, 0.56%-1.20%). SO(2) had a less plausible association: Daily deaths increased at very low concentrations, but leveled off and then decreased at higher concentrations. These findings held in both one- and two-pollutant models and held whether we optimized our weather and seasonal model in each city or used the same smoothing parameters in each city. We conclude that the association with particle levels is more convincing than for SO(2), and without a threshold. Linear models provide an adequate estimation of the effect of particulate air pollution on mortality at low to moderate concentrations. PMID:11675264

  3. Trends in mercury wet deposition and mercury air concentrations across the U.S. and Canada.

    PubMed

    Weiss-Penzias, Peter S; Gay, David A; Brigham, Mark E; Parsons, Matthew T; Gustin, Mae S; Ter Schure, Arnout

    2016-10-15

    This study examined the spatial and temporal trends of mercury (Hg) in wet deposition and air concentrations in the United States (U.S.) and Canada between 1997 and 2013. Data were obtained from the National Atmospheric Deposition Program (NADP) and Environment Canada monitoring networks, and other sources. Of the 19 sites with data records from 1997-2013, 53% had significant negative trends in Hg concentration in wet deposition, while no sites had significant positive trends, which is in general agreement with earlier studies that considered NADP data up until about 2010. However, for the time period 2007-2013 (71 sites), 17% and 13% of the sites had significant positive and negative trends, respectively, and for the time period 2008-2013 (81 sites) 30% and 6% of the sites had significant positive and negative trends, respectively. Non-significant positive tendencies were also widespread. Regional trend analyses revealed significant positive trends in Hg concentration in the Rocky Mountains, Plains, and Upper Midwest regions for the recent time periods in addition to significant positive trends in Hg deposition for the continent as a whole. Sulfate concentration trends in wet deposition were negative in all regions, suggesting a lower importance of local Hg sources. The trend in gaseous elemental Hg from short-term datasets merged as one continuous record was broadly consistent with trends in Hg concentration in wet deposition, with the early time period (1998-2007) producing a significantly negative trend (-1.5±0.2%year(-1)) and the recent time period (2008-2013) displaying a flat slope (-0.3±0.1%year(-1), not significant). The observed shift to more positive or less negative trends in Hg wet deposition primarily seen in the Central-Western regions is consistent with the effects of rising Hg emissions from regions outside the U.S. and Canada and the influence of long-range transport in the free troposphere. PMID:26803218

  4. Spatial & temporal variations of PM10 and particle number concentrations in urban air.

    PubMed

    Johansson, Christer; Norman, Michael; Gidhagen, Lars

    2007-04-01

    The size of particles in urban air varies over four orders of magnitude (from 0.001 microm to 10 microm in diameter). In many cities only particle mass concentrations (PM10, i.e. particles <10 microm diameter) is measured. In this paper we analyze how differences in emissions, background concentrations and meteorology affect the temporal and spatial distribution of PM10 and total particle number concentrations (PNC) based on measurements and dispersion modeling in Stockholm, Sweden. PNC at densely trafficked kerbside locations are dominated by ultrafine particles (<0.1 microm diameter) due to vehicle exhaust emissions as verified by high correlation with NOx. But PNC contribute only marginally to PM10, due to the small size of exhaust particles. Instead wear of the road surface is an important factor for the highest PM10 concentrations observed. In Stockholm, road wear increases drastically due to the use of studded tires and traction sand on streets during winter; up to 90% of the locally emitted PM10 may be due to road abrasion. PM10 emissions and concentrations, but not PNC, at kerbside are controlled by road moisture. Annual mean urban background PM10 levels are relatively uniformly distributed over the city, due to the importance of long range transport. For PNC local sources often dominate the concentrations resulting in large temporal and spatial gradients in the concentrations. Despite these differences in the origin of PM10 and PNC, the spatial gradients of annual mean concentrations due to local sources are of equal magnitude due to the common source, namely traffic. Thus, people in different areas experiencing a factor of 2 different annual PM10 exposure due to local sources will also experience a factor of 2 different exposure in terms of PNC. This implies that health impact studies based solely on spatial differences in annual exposure to PM10 may not separate differences in health effects due to ultrafine and coarse particles. On the other hand

  5. Spatial & temporal variations of PM10 and particle number concentrations in urban air.

    PubMed

    Johansson, Christer; Norman, Michael; Gidhagen, Lars

    2007-04-01

    The size of particles in urban air varies over four orders of magnitude (from 0.001 microm to 10 microm in diameter). In many cities only particle mass concentrations (PM10, i.e. particles <10 microm diameter) is measured. In this paper we analyze how differences in emissions, background concentrations and meteorology affect the temporal and spatial distribution of PM10 and total particle number concentrations (PNC) based on measurements and dispersion modeling in Stockholm, Sweden. PNC at densely trafficked kerbside locations are dominated by ultrafine particles (<0.1 microm diameter) due to vehicle exhaust emissions as verified by high correlation with NOx. But PNC contribute only marginally to PM10, due to the small size of exhaust particles. Instead wear of the road surface is an important factor for the highest PM10 concentrations observed. In Stockholm, road wear increases drastically due to the use of studded tires and traction sand on streets during winter; up to 90% of the locally emitted PM10 may be due to road abrasion. PM10 emissions and concentrations, but not PNC, at kerbside are controlled by road moisture. Annual mean urban background PM10 levels are relatively uniformly distributed over the city, due to the importance of long range transport. For PNC local sources often dominate the concentrations resulting in large temporal and spatial gradients in the concentrations. Despite these differences in the origin of PM10 and PNC, the spatial gradients of annual mean concentrations due to local sources are of equal magnitude due to the common source, namely traffic. Thus, people in different areas experiencing a factor of 2 different annual PM10 exposure due to local sources will also experience a factor of 2 different exposure in terms of PNC. This implies that health impact studies based solely on spatial differences in annual exposure to PM10 may not separate differences in health effects due to ultrafine and coarse particles. On the other hand

  6. Evaluation of an adsorption system to concentrate VOC in air streams prior to catalytic incineration.

    PubMed

    Campesi, María A; Luzi, Carlos D; Barreto, Guillermo F; Martínez, Osvaldo M

    2015-05-01

    Catalytic combustion is a well-developed process for the removal of volatile organic compounds (VOCs). In order to reduce both the amount of catalyst needed for incineration and the surface area of recuperative heat exchangers, an evaluation of the use of thermal swing adsorption as a previous step for VOC concentration is made. An air stream containing ethyl acetate and ethanol (employed as solvents in printing processes) has been taken as a case study. Based on the characteristics of the adsorption/desorption system and the properties of the stream to be treated, a monolithic rotor concentrator with activated carbon as adsorbent material is adopted. Once the temperature of the inlet desorption stream TD is chosen, the minimum possible desorption flow rate, WD,min, and the amount of adsorbent material can be properly defined according to the extent of the Mass Transfer Zone (MTZ) at the end of the adsorption stage. An approximate procedure to speed up the calculations needed for sizing the bed and predicting the operating variables is also presented. In the case studied here, the concentration of the VOC stream can reach 6 times that of the primary effluent when TD = 200 °C is chosen.

  7. Influence of precipitation on (7)Be concentrations in air as measured by CTBTO global monitoring system.

    PubMed

    Kusmierczyk-Michulec, J; Gheddou, A; Nikkinen, M

    2015-06-01

    Data collected by the International Monitoring System (IMS) during 2009-2012 were used to study influence of precipitation and relative humidity on changes in (7)Be concentrations in atmosphere. The significant decrease in (7)Be concentrations, corresponding to measurements collected by stations located within Intertropical Convergence Zone (ITCZ) is demonstrated. This effect can be attributed to the process of enhanced wet deposition within the ITCZ. To quantify this effect data collected by IMS stations within ITCZ were thoroughly analyzed. It was found that the atmospheric content of (7)Be strongly decreases under the rain conditions. The rain mediated depletion of (7)Be to half of its before rain value, needs about 62 h in case of light precipitation, while in the case of moderate precipitation about 38 h is needed. In addition the evaluated impact of humidity showed that increase in relative humidity by 20%, for example from 70% ± 5% to 90% ± 5% causes almost a double decrease in beryllium concentration in surface air.

  8. Evaluation of an adsorption system to concentrate VOC in air streams prior to catalytic incineration.

    PubMed

    Campesi, María A; Luzi, Carlos D; Barreto, Guillermo F; Martínez, Osvaldo M

    2015-05-01

    Catalytic combustion is a well-developed process for the removal of volatile organic compounds (VOCs). In order to reduce both the amount of catalyst needed for incineration and the surface area of recuperative heat exchangers, an evaluation of the use of thermal swing adsorption as a previous step for VOC concentration is made. An air stream containing ethyl acetate and ethanol (employed as solvents in printing processes) has been taken as a case study. Based on the characteristics of the adsorption/desorption system and the properties of the stream to be treated, a monolithic rotor concentrator with activated carbon as adsorbent material is adopted. Once the temperature of the inlet desorption stream TD is chosen, the minimum possible desorption flow rate, WD,min, and the amount of adsorbent material can be properly defined according to the extent of the Mass Transfer Zone (MTZ) at the end of the adsorption stage. An approximate procedure to speed up the calculations needed for sizing the bed and predicting the operating variables is also presented. In the case studied here, the concentration of the VOC stream can reach 6 times that of the primary effluent when TD = 200 °C is chosen. PMID:25734958

  9. Evaluation of optical source-detector configurations for tomographic reconstruction of chemical concentrations in indoor air.

    PubMed

    Todd, L; Ramachandran, G

    1994-12-01

    This article reports on numerical studies to evaluate and compare optical remote sensing configurations for tomographically reconstructing pollutant concentrations in indoor air. With a remote sensing/computed tomography system, two-dimensional maps of pollutant concentrations with good spatial resolution can be created for an entire room. The successful use of such a system for exposure assessment, ventilation assessment, or source monitoring depends on the remote sensing configuration. A systematic method was developed to evaluate the performance of 10 configurations. One hundred and twenty test maps were reconstructed with an algebraic reconstruction method using all 10 configurations; reconstruction quality was evaluated using 4 criteria. Reconstruction quality was related to the number and location of detectors in the room and the complexity of the test maps. Configurations using the same number of detectors placed in different locations resulted in reconstructions that differed in quality. The effect of reducing the number density of rays on reconstruction quality was studied. Based on these simulations, two configurations that used four detectors to scan the room were selected, and their performance was evaluated in the presence of various levels of measurement noise. Two configurations that used four detectors were most suited for exposure assessment. It was found that when designing a configuration, the number and independence of rays should be maximized. Results underscored the need to thoroughly test configurations through numerical studies prior to field implementation; a wide variety of concentration maps, relevant to the application, should be tested under both ideal and nonideal sampling conditions. PMID:7825513

  10. Seasonal variations in concentrations, distributions, and air-soil exchange fluxes of dioxin-like polychlorinated biphenyls in Shanghai, China.

    PubMed

    Tian, Yajun; Nie, Zhiqiang; He, Jie; Die, Qingqi; Fang, Yanyan; Liu, Feng; Yang, Yufei; Gao, Xingbao; Huang, Qifei

    2016-02-01

    Dioxin-like polychlorinated biphenyl (dl-PCB) concentrations in ambient air and soil in Shanghai, China, were measured to allow seasonal and spatial differences in the dl-PCB concentrations, profiles, distributions, fugacity fractions, and air-soil fluxes to be determined. The toxic equivalent (TEQ) DL-PCB concentrations in the air were higher in summer (mean 9.46 fg m(-3), range 1.32-26.3 fg m(-3)) than in winter (mean 4.57 fg m(-3), range 1.55-10.9 fg m(-3)). The DL-PCB concentrations in air were different in different areas, and the concentrations decreased in the order industrial areas > commercial and residential areas > suburban areas > rural area. The mean DL-PCB concentration in soil was 0.25 pg TEQ g(-1) dry weight (dw) and the range was 0.05-0.90 pg TEQ g(-1) dw. The highest DL-PCB concentration in soil was found in a sample from a commercial/residential area. The DL-PCB fluxes were negative (-216 pg m(-2) h(-1) in summer and -41.1 pg m(-2) h(-1) in winter), and the fugacity fractions were below 0.5, indicating that dl-PCBs in Shanghai are deposited from the air to the soil in all seasons. The net fluxes were higher in summer than in winter, and the deposition fluxes were higher in industrial areas than in other areas in both summer and winter.

  11. Schlieren imaging of loud sounds and weak shock waves in air near the limit of visibility

    NASA Astrophysics Data System (ADS)

    Hargather, Michael John; Settles, Gary S.; Madalis, Matthew J.

    2010-02-01

    A large schlieren system with exceptional sensitivity and a high-speed digital camera are used to visualize loud sounds and a variety of common phenomena that produce weak shock waves in the atmosphere. Frame rates varied from 10,000 to 30,000 frames/s with microsecond frame exposures. Sound waves become visible to this instrumentation at frequencies above 10 kHz and sound pressure levels in the 110 dB (6.3 Pa) range and above. The density gradient produced by a weak shock wave is examined and found to depend upon the profile and thickness of the shock as well as the density difference across it. Schlieren visualizations of weak shock waves from common phenomena include loud trumpet notes, various impact phenomena that compress a bubble of air, bursting a toy balloon, popping a champagne cork, snapping a wooden stick, and snapping a wet towel. The balloon burst, snapping a ruler on a table, and snapping the towel and a leather belt all produced readily visible shock-wave phenomena. In contrast, clapping the hands, snapping the stick, and the champagne cork all produced wave trains that were near the weak limit of visibility. Overall, with sensitive optics and a modern high-speed camera, many nonlinear acoustic phenomena in the air can be observed and studied.

  12. Equatorial range limits of an intertidal ectotherm are more linked to water than air temperature.

    PubMed

    Seabra, Rui; Wethey, David S; Santos, António M; Gomes, Filipa; Lima, Fernando P

    2016-10-01

    As climate change is expected to impose increasing thermal stress on intertidal organisms, understanding the mechanisms by which body temperatures translate into major biogeographic patterns is of paramount importance. We exposed individuals of the limpet Patella vulgata Linnaeus, 1758, to realistic experimental treatments aimed at disentangling the contribution of water and air temperature for the buildup of thermal stress. Treatments were designed based on temperature data collected at the microhabitat level, from 15 shores along the Atlantic European coast spanning nearly 20° of latitude. Cardiac activity data indicated that thermal stress levels in P. vulgata are directly linked to elevated water temperature, while high air temperature is only stressful if water temperature is also high. In addition, the analysis of the link between population densities and thermal regimes at the studied locations suggests that the occurrence of elevated water temperature may represent a threshold P. vulgata is unable to tolerate. By combining projected temperatures with the temperature threshold identified, we show that climate change will likely result in the westward expansion of the historical distribution gap in the Bay of Biscay (southwest France), and northward contraction of the southern range limit in south Portugal. These findings suggest that even a minor relaxing of the upwelling off northwest Iberia could lead to a dramatic increase in thermal stress, with major consequences for the structure and functioning of the intertidal communities along Iberian rocky shores.

  13. Equatorial range limits of an intertidal ectotherm are more linked to water than air temperature.

    PubMed

    Seabra, Rui; Wethey, David S; Santos, António M; Gomes, Filipa; Lima, Fernando P

    2016-10-01

    As climate change is expected to impose increasing thermal stress on intertidal organisms, understanding the mechanisms by which body temperatures translate into major biogeographic patterns is of paramount importance. We exposed individuals of the limpet Patella vulgata Linnaeus, 1758, to realistic experimental treatments aimed at disentangling the contribution of water and air temperature for the buildup of thermal stress. Treatments were designed based on temperature data collected at the microhabitat level, from 15 shores along the Atlantic European coast spanning nearly 20° of latitude. Cardiac activity data indicated that thermal stress levels in P. vulgata are directly linked to elevated water temperature, while high air temperature is only stressful if water temperature is also high. In addition, the analysis of the link between population densities and thermal regimes at the studied locations suggests that the occurrence of elevated water temperature may represent a threshold P. vulgata is unable to tolerate. By combining projected temperatures with the temperature threshold identified, we show that climate change will likely result in the westward expansion of the historical distribution gap in the Bay of Biscay (southwest France), and northward contraction of the southern range limit in south Portugal. These findings suggest that even a minor relaxing of the upwelling off northwest Iberia could lead to a dramatic increase in thermal stress, with major consequences for the structure and functioning of the intertidal communities along Iberian rocky shores. PMID:27109165

  14. Al-Air Batteries: Fundamental Thermodynamic Limitations from First Principles Theory

    NASA Astrophysics Data System (ADS)

    Chen, Leanne D.; Noerskov, Jens K.; Luntz, Alan C.

    2015-03-01

    The Al-air battery possesses high theoretical specific energy (4140 Wh/kg) and is therefore an attractive candidate for vehicle propulsion applications. However, the experimentally observed open-circuit potential is much lower than what thermodynamics predicts, and this potential loss is widely believed to be an effect of corrosion. We present a detailed study of the Al-air battery using density functional theory. The results suggest that the difference between bulk thermodynamic and surface potentials is due to both the effects of asymmetry in multi-electron transfer reactions that define the anodic dissolution of Al and, more importantly, a large chemical step inherent to the formation of bulk Al(OH)3 from surface intermediates. The former results in an energy loss of 3%, while the latter accounts for 14 -29% of the total thermodynamic energy depending on the surface site where dissolution occurs. Therefore, the maximum open-circuit potential of the Al anode is only -1.87 V vs. SHE in the absence of thermal excitations, contrary to -2.34 V predicted by bulk thermodynamics at pH 14.6. This is a fundamental limitation of the system and governs the maximum output potential, which cannot be improved even if corrosion effects were completely suppressed. Supported by the Natural Sciences and Engineering Research Council of Canada and the ReLiable Project (#11-116792) funded by the Danish Council for Strategic Research.

  15. Al-Air Batteries: Fundamental Thermodynamic Limitations from First-Principles Theory.

    PubMed

    Chen, Leanne D; Nørskov, Jens K; Luntz, Alan C

    2015-01-01

    The Al-air battery possesses high theoretical specific energy (4140 W h/kg) and is therefore an attractive candidate for vehicle propulsion. However, the experimentally observed open-circuit potential is much lower than what bulk thermodynamics predicts, and this potential loss is typically attributed to corrosion. Similarly, large Tafel slopes associated with the battery are assumed to be due to film formation. We present a detailed thermodynamic study of the Al-air battery using density functional theory. The results suggest that the maximum open-circuit potential of the Al anode is only -1.87 V versus the standard hydrogen electrode at pH 14.6 instead of the traditionally assumed -2.34 V and that large Tafel slopes are inherent in the electrochemistry. These deviations from the bulk thermodynamics are intrinsic to the electrochemical surface processes that define Al anodic dissolution. This has contributions from both asymmetry in multielectron transfers and, more importantly, a large chemical stabilization inherent to the formation of bulk Al(OH)3 from surface intermediates. These are fundamental limitations that cannot be improved even if corrosion and film effects are completely suppressed. PMID:26263108

  16. Limitations of symmetry in FE modeling: A comparison of fem and air-coupled resonance imaging

    NASA Astrophysics Data System (ADS)

    Livings, R. A.; Dayal, V.; Barnard, D. J.; Hsu, D. K.

    2012-05-01

    It has long been an accepted practice to use symmetry in Finite Element Modeling. Whenever modeling a large structure, we turn to symmetry in order to significantly reduce the model size and computation time. But is symmetry always the solution to long computation times, and is it always accurate? This study is aimed at modeling a whole ceramic tile and several possible symmetric models under several different loading cases and comparing them to each other and Air-Coupled Ultrasonic scans to determine if the Finite Element Models can accurately predict the vibrational resonance patterns. The reason for the accuracy or inaccuracy will also be examined. The understanding of the limitations of using symmetry to model large structures will be very useful in all future modeling.

  17. Diffraction-limited Fabry-Perot cavity in the near concentric regime

    NASA Astrophysics Data System (ADS)

    Durak, K.; Nguyen, C. H.; Leong, V.; Straupe, S.; Kurtsiefer, C.

    2014-10-01

    Nearly concentric optical cavities can be used to prepare optical fields with a very small mode volume. We implement an anaclastic design of such a cavity that significantly simplifies mode matching to the fundamental cavity mode. The cavity is shown to have diffraction-limited performance for a mode volume of ≈ {{10}4}{{λ }3}. This is in sharp contrast with the behavior of cavities with plano-concave mirrors, where aberrations significantly decrease the coupling of the input mode to the fundamental mode of the cavity and increase the coupling to the higher-order modes. We estimate the related cavity quantum electrodynamics parameters and show that the proposed cavity design allows for strong coupling without a need for high finesse or small physical-cavity volume.

  18. Limits to anaerobic energy and cytosolic concentration in the living cell

    NASA Astrophysics Data System (ADS)

    Paglietti, A.

    2015-11-01

    For many physical systems at any given temperature, the set of all states where the system's free energy reaches its largest value can be determined from the system's constitutive equations of internal energy and entropy, once a state of that set is known. Such an approach is fraught with complications when applied to a living cell, because the cell's cytosol contains thousands of solutes, and thus thousands of state variables, which makes determination of its state impractical. We show here that, when looking for the maximum energy that the cytosol can store and release, detailed information on cytosol composition is redundant. Compatibility with cell's life requires that a single variable that represents the overall concentration of cytosol solutes must fall between defined limits, which can be determined by dehydrating and overhydrating the cell to its maximum capacity. The same limits are shown to determine, in particular, the maximum amount of free energy that a cell can supply in fast anaerobic processes, starting from any given initial state. For a typical skeletal muscle in normal physiological conditions this energy, i.e., the maximum anaerobic capacity to do work, is calculated to be about 960 J per kg of muscular mass. Such energy decreases as the overall concentration of solutes in the cytosol is increased. Similar results apply to any kind of cell. They provide an essential tool to understand and control the macroscopic response of single cells and multicellular cellular tissues alike. The applications include sport physiology, cell aging, disease produced cell damage, drug absorption capacity, to mention the most obvious ones.

  19. Incorporation of concentration data below the limit of quantification in population pharmacokinetic analyses

    PubMed Central

    Keizer, Ron J; Jansen, Robert S; Rosing, Hilde; Thijssen, Bas; Beijnen, Jos H; Schellens, Jan H M; Huitema, Alwin D R

    2015-01-01

    Handling of data below the lower limit of quantification (LLOQ), below the limit of quantification (BLOQ) in population pharmacokinetic (PopPK) analyses is important for reducing bias and imprecision in parameter estimation. We aimed to evaluate whether using the concentration data below the LLOQ has superior performance over several established methods. The performance of this approach (“All data”) was evaluated and compared to other methods: “Discard,” “LLOQ/2,” and “LIKE” (likelihood-based). An analytical and residual error model was constructed on the basis of in-house analytical method validations and analyses from literature, with additional included variability to account for model misspecification. Simulation analyses were performed for various levels of BLOQ, several structural PopPK models, and additional influences. Performance was evaluated by relative root mean squared error (RMSE), and run success for the various BLOQ approaches. Performance was also evaluated for a real PopPK data set. For all PopPK models and levels of censoring, RMSE values were lowest using “All data.” Performance of the “LIKE” method was better than the “LLOQ/2” or “Discard” method. Differences between all methods were small at the lowest level of BLOQ censoring. “LIKE” method resulted in low successful minimization (<50%) and covariance step success (<30%), although estimates were obtained in most runs (∼90%). For the real PK data set (7.4% BLOQ), similar parameter estimates were obtained using all methods. Incorporation of BLOQ concentrations showed superior performance in terms of bias and precision over established BLOQ methods, and shown to be feasible in a real PopPK analysis. PMID:26038706

  20. Ballast water regulations and the move toward concentration-based numeric discharge limits.

    PubMed

    Albert, Ryan J; Lishman, John M; Saxena, Juhi R

    2013-03-01

    Ballast water from shipping is a principal source for the introduction of nonindigenous species. As a result, numerous government bodies have adopted various ballast water management practices and discharge standards to slow or eliminate the future introduction and dispersal of these nonindigenous species. For researchers studying ballast water issues, understanding the regulatory framework is helpful to define the scope of research needed by policy makers to develop effective regulations. However, for most scientists, this information is difficult to obtain because it is outside the standard scientific literature and often difficult to interpret. This paper provides a brief review of the regulatory framework directed toward scientists studying ballast water and aquatic invasive species issues. We describe different approaches to ballast water management in international, U.S. federal and state, and domestic ballast water regulation. Specifically, we discuss standards established by the International Maritime Organization (IMO), the U.S. Coast Guard and U.S. Environmental Protection Agency, and individual states in the United States including California, New York, and Minnesota. Additionally, outside the United States, countries such as Australia, Canada, and New Zealand have well-established domestic ballast water regulatory regimes. Different approaches to regulation have recently resulted in variations between numeric concentration-based ballast water discharge limits, particularly in the United States, as well as reliance on use of ballast water exchange pending development and adoption of rigorous science-based discharge standards. To date, numeric concentration-based discharge limits have not generally been based upon a thorough application of risk-assessment methodologies. Regulators, making decisions based on the available information and methodologies before them, have consequently established varying standards, or not established standards at all. The

  1. Ballast water regulations and the move toward concentration-based numeric discharge limits.

    PubMed

    Albert, Ryan J; Lishman, John M; Saxena, Juhi R

    2013-03-01

    Ballast water from shipping is a principal source for the introduction of nonindigenous species. As a result, numerous government bodies have adopted various ballast water management practices and discharge standards to slow or eliminate the future introduction and dispersal of these nonindigenous species. For researchers studying ballast water issues, understanding the regulatory framework is helpful to define the scope of research needed by policy makers to develop effective regulations. However, for most scientists, this information is difficult to obtain because it is outside the standard scientific literature and often difficult to interpret. This paper provides a brief review of the regulatory framework directed toward scientists studying ballast water and aquatic invasive species issues. We describe different approaches to ballast water management in international, U.S. federal and state, and domestic ballast water regulation. Specifically, we discuss standards established by the International Maritime Organization (IMO), the U.S. Coast Guard and U.S. Environmental Protection Agency, and individual states in the United States including California, New York, and Minnesota. Additionally, outside the United States, countries such as Australia, Canada, and New Zealand have well-established domestic ballast water regulatory regimes. Different approaches to regulation have recently resulted in variations between numeric concentration-based ballast water discharge limits, particularly in the United States, as well as reliance on use of ballast water exchange pending development and adoption of rigorous science-based discharge standards. To date, numeric concentration-based discharge limits have not generally been based upon a thorough application of risk-assessment methodologies. Regulators, making decisions based on the available information and methodologies before them, have consequently established varying standards, or not established standards at all. The

  2. [Concentration of allergic fungi spores in the air of flats in Lódź].

    PubMed

    Krawczyk, P; Kowalski, M L; Ochecka-Szymańska, A

    1999-01-01

    The real contribution of moulds to the pathogenesis of allergic diseases remains unknown, although positive skin prick tests and/or specific serum IgE to moki allergens can be detected in 1-5% of atopic patients. A significant problem in assesment of exposure to mould allergens, resulting with difficulty in standarization of methods. The aim of this work was to assess the concentration of spores of 8 mould species in flats inhabited by peoples who Bont show any symptoms of allergy. The Open Petri Dish (OPD) method involving sedimentation of participles contained in the column of air over the dish was used to assess the number of spores in 1 m3 of indoor atmospheres. All colonies were counted, but only 8 mould species implicated in inhaled allergy were identified, ie.: Alternaria tenuis, Cladosporium herbarum, Helminthosporum halodes, Pullularia pullulans, Penicillium notatam, Rhizopus nigricans, Mucor mucedo, Aspergillus fumigatus. The tests were carried out in 10 flats located in various quarters of the cify of Lodź during three consecutive days of September 1995 between 5:00 pm and 6:04 pm. In analyzing the percentage of spores of each of the eight mould species tested we determined that, independent of fiat and test day, C. herbarum predominated. It is good agreement with the observations of other authors who report that among large quantities of fungi that are detected in late summer, usually C. herbarum spores dominate. This is the season when the incidence of the Cladosporium spores in the atmospheric air increases. Spores of H. halodes were detected least frequently. Our study demonstrated the presence of substantial amounts of mould spores in indoor air of houses in Lódź. The spores belong to species with documented allergenicity, suggesting that they may play a role in development of allergic sensitization in susceptible subjects.

  3. Effects of trans-Eurasian transport of air pollutants on surface ozone concentrations over Western China

    NASA Astrophysics Data System (ADS)

    Li, Xiaoyuan; Liu, Junfeng; Mauzerall, Denise L.; Emmons, Louisa K.; Walters, Stacy; Horowitz, Larry W.; Tao, Shu

    2014-11-01

    Due to a lack of industrialization in Western China, surface air there was, until recently, believed to be relatively unpolluted. However, recent measurements and modeling studies have found high levels of ozone (O3) there. Based on the state-of-the-science global chemical transport model MOZART-4, we identify the origin, pathway, and mechanism of trans-Eurasian transport of air pollutants to Western China in 2000. MOZART-4 generally simulates well the observed surface O3 over inland areas of China. Simulations find surface ozone concentrations over Western China on average to be about 10 ppbv higher than Eastern China. Using sensitivity studies, we find that anthropogenic emissions from all Eurasian regions except China contribute 10-15 ppbv surface O3 over Western China, superimposed upon a 35-40 ppbv natural background. Transport from European anthropogenic sources to Northwestern China results in 2-6 ppbv O3 enhancements in spring and summer. Indian anthropogenic sources strongly influence O3 over the Tibetan Plateau during the summer monsoon. Transport of O3 originating from emissions in the Middle East occasionally reach Western China and increase surface ozone there by about 1-4 ppbv. These influences are of similar magnitude as trans-Pacific and transatlantic transport of O3 and its precursors, indicating the significance of trans-Eurasian ozone transport in hemispheric transport of air pollution. Our study further indicates that mitigation of anthropogenic emissions from Europe, the Indian subcontinent, and the Middle East could benefit public health and agricultural productivity in Western China.

  4. [Concentration of allergic fungi spores in the air of flats in Lódź].

    PubMed

    Krawczyk, P; Kowalski, M L; Ochecka-Szymańska, A

    1999-01-01

    The real contribution of moulds to the pathogenesis of allergic diseases remains unknown, although positive skin prick tests and/or specific serum IgE to moki allergens can be detected in 1-5% of atopic patients. A significant problem in assesment of exposure to mould allergens, resulting with difficulty in standarization of methods. The aim of this work was to assess the concentration of spores of 8 mould species in flats inhabited by peoples who Bont show any symptoms of allergy. The Open Petri Dish (OPD) method involving sedimentation of participles contained in the column of air over the dish was used to assess the number of spores in 1 m3 of indoor atmospheres. All colonies were counted, but only 8 mould species implicated in inhaled allergy were identified, ie.: Alternaria tenuis, Cladosporium herbarum, Helminthosporum halodes, Pullularia pullulans, Penicillium notatam, Rhizopus nigricans, Mucor mucedo, Aspergillus fumigatus. The tests were carried out in 10 flats located in various quarters of the cify of Lodź during three consecutive days of September 1995 between 5:00 pm and 6:04 pm. In analyzing the percentage of spores of each of the eight mould species tested we determined that, independent of fiat and test day, C. herbarum predominated. It is good agreement with the observations of other authors who report that among large quantities of fungi that are detected in late summer, usually C. herbarum spores dominate. This is the season when the incidence of the Cladosporium spores in the atmospheric air increases. Spores of H. halodes were detected least frequently. Our study demonstrated the presence of substantial amounts of mould spores in indoor air of houses in Lódź. The spores belong to species with documented allergenicity, suggesting that they may play a role in development of allergic sensitization in susceptible subjects. PMID:16886472

  5. A critical review of reported air concentrations of organic compounds in aircraft cabins.

    PubMed

    Nagda, N L; Rector, H E

    2003-09-01

    This paper presents a review and assessment of aircraft cabin air quality studies with measured levels of volatile and semivolatile organic compounds (VOCs and SVOCs). VOC and SVOC concentrations reported for aircraft cabins are compared with those reported for residential and office buildings and for passenger compartments of other types of transportation. An assessment of measurement technologies and quality assurance procedures is included. The six studies reviewed in the paper range in coverage from two to about 30 flights per study. None of the monitored flights included any unusual or episodic events that could affect cabin air quality. Most studies have used scientifically sound methods for measurements. Study results indicate that under routine aircraft operations, contaminant levels in aircraft cabins are similar to those in residential and office buildings, with two exceptions: (1). levels of ethanol and acetone, indicators of bioeffluents and chemicals from consumer products are higher in aircraft than in home or office environments, and (2). levels of certain chlorinated hydrocarbons and fuel-related contaminants are higher in residential/office buildings than in aircraft. Similarly, ethanol and acetone levels are higher in aircraft than in other transportation modes but the levels of some pollutants, such as m-/p-xylenes, tend to be lower in aircraft.

  6. Water complexes of important air pollutants: geometries, complexation energies, concentrations, infrared spectra, and intrinsic reactivity.

    PubMed

    Galano, Annia; Narciso-Lopez, Marcela; Francisco-Marquez, Misaela

    2010-05-13

    Water complexes involving methanol, ethanol, formaldehyde, formic acid, acetone, ammonia, acetylene, ethylene, chloroethene, trichloroethene, 1,1,1-trichloroethane, hydroxyl radical, and hydroperoxyl radical have been studied. Enthalpies, entropies, and Gibbs free energies of association have been estimated, as well as the concentrations of the complexes under lower-troposphere conditions. The influence of the relative air humidity on the complexation processes has been analyzed. The association processes yielding water complexes of methanol, ethanol, formic acid, ammonia, acetone, hydroxyl radical, and hydroperoxyl radical were found to be more exothermic than that of the water dimer. General trends for the reactivity of the studied water complexes, compared to those of the corresponding free species, are proposed based on global reactivity indexes. The previously reported increased reactivity of the (*)OOH self-reaction, when there is water present, has been explained. The IR spectra of the complexes have been analyzed and compared with those of the free species. PMID:20394451

  7. Assessment of concentrations of trace elements in ground water and soil at the Small-Arms Firing Range, Shaw Air Force Base, South Carolina

    USGS Publications Warehouse

    Landmeyer, J.E.

    1994-01-01

    Ground-water samples were collected from four shallow water-table aquifer observation wells beneath the Small-Arms Firing Range study area at Shaw Air Force Base. Water-chemistry analyses indicated that total lead concentrations in shallow ground water beneath the study area do not exceed the U.S. Environmental Protection Agency maximum contaminant level established for lead in drinking water (0.05 milligrams per liter). All other trace element total concentrations in ground water beneath the study area were at or below the detection limit of the analytical methodology.

  8. Nitrogen Limitation Alters Biomass Production but Enhances Steviol Glycoside Concentration in Stevia rebaudiana Bertoni.

    PubMed

    Barbet-Massin, Claire; Giuliano, Simon; Alletto, Lionel; Daydé, Jean; Berger, Monique

    2015-01-01

    The need for medicinal and aromatic plants for industrial uses creates an opportunity for farmers to produce alternative crops. Stevia rebaudiana Bertoni, a perennial shrub originating from Paraguay, is of increasing interest as a source of zero-calorie natural sweeteners: the steviol glycosides (SVglys). The aim of this study was to investigate the relevance of nitrogen (N) supply for leaf yield and for SVgly concentrations in leaves, which are the two major components of S. rebaudiana productivity. In this regard, the relationship between leaf N concentration, CO2 assimilation, leaf production and SVgly accumulation was investigated. The experiments were conducted consecutively in growth-chamber (CC: controlled conditions), in greenhouse (SCC: semi-controlled conditions) and in field conditions (FC) on two genotypes. In CC and SCC, three levels of N fertilization were applied. Plants were grown on four locations in the FC experiment. Both N supply (CC and SCC) and location (FC) had a significant effect on N content in leaves. When light was not limiting (SCC and FC) N content in leaves was positively correlated with CO2 assimilation rate and biomass accumulation. Irrespective of the growth conditions, N content in leaves was negatively correlated with SVgly content. However, increased SVgly content was correlated with a decreased ratio of rebaudioside A over stevioside. The evidence that the increased SVgly accumulation compensates for the negative effect on biomass production suggests that adequate SVgly productivity per plant may be achieved with relatively low fertilization. PMID:26192921

  9. Nitrogen Limitation Alters Biomass Production but Enhances Steviol Glycoside Concentration in Stevia rebaudiana Bertoni.

    PubMed

    Barbet-Massin, Claire; Giuliano, Simon; Alletto, Lionel; Daydé, Jean; Berger, Monique

    2015-01-01

    The need for medicinal and aromatic plants for industrial uses creates an opportunity for farmers to produce alternative crops. Stevia rebaudiana Bertoni, a perennial shrub originating from Paraguay, is of increasing interest as a source of zero-calorie natural sweeteners: the steviol glycosides (SVglys). The aim of this study was to investigate the relevance of nitrogen (N) supply for leaf yield and for SVgly concentrations in leaves, which are the two major components of S. rebaudiana productivity. In this regard, the relationship between leaf N concentration, CO2 assimilation, leaf production and SVgly accumulation was investigated. The experiments were conducted consecutively in growth-chamber (CC: controlled conditions), in greenhouse (SCC: semi-controlled conditions) and in field conditions (FC) on two genotypes. In CC and SCC, three levels of N fertilization were applied. Plants were grown on four locations in the FC experiment. Both N supply (CC and SCC) and location (FC) had a significant effect on N content in leaves. When light was not limiting (SCC and FC) N content in leaves was positively correlated with CO2 assimilation rate and biomass accumulation. Irrespective of the growth conditions, N content in leaves was negatively correlated with SVgly content. However, increased SVgly content was correlated with a decreased ratio of rebaudioside A over stevioside. The evidence that the increased SVgly accumulation compensates for the negative effect on biomass production suggests that adequate SVgly productivity per plant may be achieved with relatively low fertilization.

  10. Nitrogen Limitation Alters Biomass Production but Enhances Steviol Glycoside Concentration in Stevia rebaudiana Bertoni

    PubMed Central

    Barbet-Massin, Claire; Giuliano, Simon; Alletto, Lionel; Daydé, Jean; Berger, Monique

    2015-01-01

    The need for medicinal and aromatic plants for industrial uses creates an opportunity for farmers to produce alternative crops. Stevia rebaudiana Bertoni, a perennial shrub originating from Paraguay, is of increasing interest as a source of zero-calorie natural sweeteners: the steviol glycosides (SVglys). The aim of this study was to investigate the relevance of nitrogen (N) supply for leaf yield and for SVgly concentrations in leaves, which are the two major components of S. rebaudiana productivity. In this regard, the relationship between leaf N concentration, CO2 assimilation, leaf production and SVgly accumulation was investigated. The experiments were conducted consecutively in growth-chamber (CC: controlled conditions), in greenhouse (SCC: semi-controlled conditions) and in field conditions (FC) on two genotypes. In CC and SCC, three levels of N fertilization were applied. Plants were grown on four locations in the FC experiment. Both N supply (CC and SCC) and location (FC) had a significant effect on N content in leaves. When light was not limiting (SCC and FC) N content in leaves was positively correlated with CO2 assimilation rate and biomass accumulation. Irrespective of the growth conditions, N content in leaves was negatively correlated with SVgly content. However, increased SVgly content was correlated with a decreased ratio of rebaudioside A over stevioside. The evidence that the increased SVgly accumulation compensates for the negative effect on biomass production suggests that adequate SVgly productivity per plant may be achieved with relatively low fertilization. PMID:26192921

  11. Combustor exhaust-emissions and blowout-limits with diesel number 2 and jet A fuels utilizing air-atomizing and pressure atomizing nozzles

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.; Norgren, C. T.

    1975-01-01

    Experimental tests with diesel number 2 and Jet A fuels were conducted in a combustor segment to obtain comparative data on exhaust emissions and blowout limits. An air-atomizing nozzle was used to inject the fuels. Tests were also made with diesel number 2 fuel using a pressure-atomizing nozzle to determine the effectiveness of the air-atomizing nozzle in reducing exhaust emissions. Test conditions included fuel-air ratios of 0.008 to 0.018, inlet-air total pressures and temperatures of 41 to 203 newtons per square centimeter and 477 to 811 K, respectively, and a reference velocity of 21.3 meters per second. Smoke number and unburned hydrocarbons were twice as high with diesel number 2 as with Jet A fuel. This was attributed to diesel number 2 having a higher concentration of aromatics and lower volatility than Jet A fuel. Oxides of nitrogen, carbon monoxide, and blowout limits were approximately the same for the two fuels. The air-atomizing nozzle, as compared with the pressure-atomizing nozzle, reduced oxides-of-nitrogen by 20 percent, smoke number by 30 percent, carbon monoxide by 70 percent, and unburned hydrocarbons by 50 percent when used with diesel number 2 fuel.

  12. Determinants of perceived air pollution annoyance and association between annoyance scores and air pollution (PM 2.5, NO 2) concentrations in the European EXPOLIS study

    NASA Astrophysics Data System (ADS)

    Rotko, Tuulia; Oglesby, Lucy; Künzli, Nino; Carrer, Paolo; Nieuwenhuijsen, Mark J.; Jantunen, Matti

    Apart from its traditionally considered objective impacts on health, air pollution can also have perceived effects, such as annoyance. The psychological effects of air pollution may often be more important to well-being than the biophysical effects. Health effects of perceived annoyance from air pollution are so far unknown. More knowledge of air pollution annoyance levels, determinants and also associations with different air pollution components is needed. In the European air pollution exposure study, EXPOLIS, the air pollution annoyance as perceived at home, workplace and in traffic were surveyed among other study objectives. Overall 1736 randomly drawn 25-55-yr-old subjects participated in six cities (Athens, Basel, Milan, Oxford, Prague and Helsinki). Levels and predictors of individual perceived annoyances from air pollution were assessed. Instead of the usual air pollution concentrations at fixed monitoring sites, this paper compares the measured microenvironment concentrations and personal exposures of PM 2.5 and NO 2 to the perceived annoyance levels. A considerable proportion of the adults surveyed was annoyed by air pollution. Female gender, self-reported respiratory symptoms, downtown living and self-reported sensitivity to air pollution were directly associated with high air pollution annoyance score while in traffic, but smoking status, age or education level were not significantly associated. Population level annoyance averages correlated with the city average exposure levels of PM 2.5 and NO 2. A high correlation was observed between the personal 48-h PM 2.5 exposure and perceived annoyance at home as well as between the mean annoyance at work and both the average work indoor PM 2.5 and the personal work time PM 2.5 exposure. With the other significant determinants (gender, city code, home location) and home outdoor levels the model explained 14% (PM 2.5) and 19% (NO 2) of the variation in perceived air pollution annoyance in traffic. Compared to

  13. Evaluation of ambient air concentrations of polycyclic aromatic hydrocarbons in Germany from 1990 to 1998.

    PubMed

    Fertmann, Regina; Tesseraux, Irene; Schümann, Michael; Neus, Hermann

    2002-03-01

    All available polycyclic aromatic hydrocarbon (PAH) concentration data in ambient air obtained over the past 10 years in Germany were evaluated to clarify whether it is justified to use benzo(a)pyrene (BaP) as a marker compound for the total PAH exposure. The data basis comprises annual mean concentrations from 1990 to 1998 supplied by the emission protection authorities of the federal states with additional information on the region, year and site of measurement. The data are very heterogeneous with respect to sample size, the number of individual PAHs analyzed, place of origin and year. Nine of 25 individual compounds with sufficient sample size (74concentration data of BaA, BeP, BaP, DBA, BghiP, COR, BbF, BkF and INP are not normally distributed and demonstrate great variability. Location, East-West differences persisting after the German reunion and time characterize the distributive patterns, e.g., from 1991 to 1997, a significant decrease in BaP could be determined based on the data from North Rhine-Westphalia (1991, N=51, median 1.6 ng/m(3); 1997, N=45, median 0.7 ng/m(3); Pconcentrations in the new federal states in the East (N=80, median 2.2 ng/m(3)) are about twice as high compared to the ones in the old federal states in the West (N=438, median 1.1 ng/m(3); P

  14. Measurements of soot, OH, and PAH concentrations in turbulent ethylene/air jet flames

    SciTech Connect

    Lee, Seong-Young; Turns, Stephen R.; Santoro, Robert J.

    2009-12-15

    This paper presents results from an investigation of soot formation in turbulent, non-premixed, C{sub 2}H{sub 4}/air jet flames. Tests were conducted using a H{sub 2}-piloted burner with fuel issuing from a 2.18 mm i.d. tube into quiescent ambient air. A range of test conditions was studied using the initial jet velocity (16.2-94.1 m/s) as a parameter. Fuel-jet Reynolds numbers ranged from 4000 to 23,200. Planar laser-induced incandescence (LII) was employed to determine soot volume fractions, and laser-induced fluorescence (LIF) was used to measure relative hydroxyl radical (OH) concentrations and polycyclic aromatic hydrocarbons (PAHs) concentrations. Extensive information on the structure of the soot and OH fields was obtained from two-dimensional imaging experiments. Quantitative measurements were obtained by employing the LII and LIF techniques independently. Imaging results for soot, OH, and PAH show the existence of three soot formation/oxidation regions: a rapid soot growth region, in which OH and soot particles lie in distinctly different radial locations; a mixing-dominated region controlled by large-scale motion; and a soot-oxidation region in which the OH and soot fields overlap spatially, resulting in the rapid oxidation of soot particles. Detailed quantitative analyzes of soot volume fractions and OH and soot zone thicknesses were performed along with the temperature measurement using the N{sub 2}-CARS system. Measurements of OH and soot zone thicknesses show that the soot zone thickness increases linearly with axial distance in the soot formation region, whereas the OH zone thickness is nearly constant in this region. The OH zone thickness then rapidly increases with downstream distance and approximately doubles in the soot-oxidation region. Probability density functions also were obtained for soot volume fractions and OH concentrations. These probability density functions clearly define the spatial relationships among the OH, PAH concentrations, the

  15. A modeling framework for characterizing near-road air pollutant concentration at community scales.

    PubMed

    Chang, Shih Ying; Vizuete, William; Valencia, Alejandro; Naess, Brian; Isakov, Vlad; Palma, Ted; Breen, Michael; Arunachalam, Saravanan

    2015-12-15

    In this study, we combine information from transportation network, traffic emissions, and dispersion model to develop a framework to inform exposure estimates for traffic-related air pollutants (TRAPs) with a high spatial resolution. A Research LINE source dispersion model (R-LINE) is used to model multiple TRAPs from roadways at Census-block level for two U.S. regions. We used a novel Space/Time Ordinary Kriging (STOK) approach that uses data from monitoring networks to provide urban background concentrations. To reduce the computational burden, we developed and applied the METeorologically-weighted Averaging for Risk and Exposure (METARE) approach with R-LINE, where a set of selected meteorological data and annual average daily traffic (AADT) are used to obtain annual averages. Compared with explicit modeling, using METARE reduces CPU-time by 88-fold (46.8h versus 32min), while still retaining accuracy of exposure estimates. We show two examples in the Piedmont region in North Carolina (~105,000 receptors) and Portland, Maine (~7000 receptors) to characterize near-road air quality. Concentrations for NOx, PM2.5, and benzene in Portland drop by over 40% within 200m away from the roadway. The concentration drop in North Carolina is less than that in Portland, as previously shown in an observation-based study, showing the robustness of our approach. Heavy-duty diesel vehicles (HDDV) contribute over 55% of NOx and PM2.5 near interstate highways, while light-duty gasoline vehicles (LDGV) contribute over 50% of benzene to urban areas where multiple roadways intersect. Normalized mean error (NME) between explicit modeling and METARE in Portland ranges from 12.6 to 14.5% and normalized mean bias (NMB) ranges from -12.9 to -11.2%. When considering a static emission rate (i.e. the emission does not have temporal variability), both NME and NMB improved (10.5% and -9.5%). Modeled concentrations in Detroit, Michigan at an array of near-road monitors are within a factor of 2

  16. A modeling framework for characterizing near-road air pollutant concentration at community scales.

    PubMed

    Chang, Shih Ying; Vizuete, William; Valencia, Alejandro; Naess, Brian; Isakov, Vlad; Palma, Ted; Breen, Michael; Arunachalam, Saravanan

    2015-12-15

    In this study, we combine information from transportation network, traffic emissions, and dispersion model to develop a framework to inform exposure estimates for traffic-related air pollutants (TRAPs) with a high spatial resolution. A Research LINE source dispersion model (R-LINE) is used to model multiple TRAPs from roadways at Census-block level for two U.S. regions. We used a novel Space/Time Ordinary Kriging (STOK) approach that uses data from monitoring networks to provide urban background concentrations. To reduce the computational burden, we developed and applied the METeorologically-weighted Averaging for Risk and Exposure (METARE) approach with R-LINE, where a set of selected meteorological data and annual average daily traffic (AADT) are used to obtain annual averages. Compared with explicit modeling, using METARE reduces CPU-time by 88-fold (46.8h versus 32min), while still retaining accuracy of exposure estimates. We show two examples in the Piedmont region in North Carolina (~105,000 receptors) and Portland, Maine (~7000 receptors) to characterize near-road air quality. Concentrations for NOx, PM2.5, and benzene in Portland drop by over 40% within 200m away from the roadway. The concentration drop in North Carolina is less than that in Portland, as previously shown in an observation-based study, showing the robustness of our approach. Heavy-duty diesel vehicles (HDDV) contribute over 55% of NOx and PM2.5 near interstate highways, while light-duty gasoline vehicles (LDGV) contribute over 50% of benzene to urban areas where multiple roadways intersect. Normalized mean error (NME) between explicit modeling and METARE in Portland ranges from 12.6 to 14.5% and normalized mean bias (NMB) ranges from -12.9 to -11.2%. When considering a static emission rate (i.e. the emission does not have temporal variability), both NME and NMB improved (10.5% and -9.5%). Modeled concentrations in Detroit, Michigan at an array of near-road monitors are within a factor of 2

  17. On eddy accumulation with limited conditional sampling to measure air-surface exchange

    SciTech Connect

    Wesely, M.L.; Hart, R.L.

    1994-01-01

    An analysis of turbulence data collected at a height of 12.3 m above grasslands was carried out to illustrate some of the limitations and possible improvements in methods to compute vertical fluxes of trace substances by the eddy accumulation technique with conditional sampling. The empirical coefficient used in the technique has a slight dependence on atmospheric stability, which can be minimized by using a threshold vertical velocity equal to approximately 0.75{sigma}{sub w}, below which chemical sampling is suspended. This protocol results in a smaller chemical sample but increases the differences in concentrations by approximately 70%. For effective conditional sampling when mass is being accumulated in a trap or reservoir, the time of sampling during updrafts versus downdrafts should be measured and used to adjust estimates of the mean concentrations.

  18. Vapor-phase and particulate-associated pesticides and PCB concentrations in eastern North Dakota air samples

    SciTech Connect

    Hawthorne, S.B.; Miller, D.J.; Louie, P.K.K.

    1996-05-01

    Vapor-phase and suspended particulate (<50 {mu}m) samples were collected on polyurethane foam (PUF) and quartz fiber filters in rural North Dakota to determine the air concentrations of pesticides in an area where agriculture is a primary source of semivolatile pollutants. Samples were collected at two sites from 1992 to 1994 that were at least 0.4 km from the nearest farmed fields and known application of pesticides, and analyzed for 22 different organochlorine, triazine, and acid herbicide pesticides. Fourteen pesticides were found above the detection limits (typically <1 pg/m{sup 3}). Concentrations of polychlorinated biphenyl (PCB) congeners were much lower (<50 pg/m{sup 3} in all cases) than many of the pesticides. These results demonstrate that pesticides are among the most prevalent chlorinated semivolatile pollutants present in rural North Dakota, that significant transport of pesticides occurs both in the vapor-phase and on suspended particulate matter, and that blown soil may be a significant mechanism for introducing pesticides into surface and ground waters. 32 refs., 2 figs., 4 tabs.

  19. Soil air CO2 concentration as an integrative parameter of soil structure

    NASA Astrophysics Data System (ADS)

    Ebeling, Corinna; Gaertig, Thorsten; Fründ, Heinz-Christian

    2015-04-01

    The assessment of soil structure is an important but difficult issue and normally takes place in the laboratory. Typical parameters are soil bulk density, porosity, water or air conductivity or gas diffusivity. All methods are time-consuming. The integrative parameter soil air CO2 concentration ([CO2]) can be used to assess soil structure in situ and in a short time. Several studies highlighted that independent of soil respiration, [CO2] in the soil air increases with decreasing soil aeration. Therefore, [CO2] is a useful indicator of soil aeration. Embedded in the German research project RÜWOLA, which focus on soil protection at forest sites, we investigated soil compaction and recovery of soil structure after harvesting. Therefore, we measured soil air CO2 concentrations continuously and in single measurements and compared the results with the measurements of bulk density, porosity and gas diffusivity. Two test areas were investigated: At test area 1 with high natural regeneration potential (clay content approx. 25 % and soil-pH between 5 and 7), solid-state CO2-sensors using NDIR technology were installed in the wheel track of different aged skidding tracks in 5 and 10 cm soil depths. At area 2 (acidic silty loam, soil-pH between 3.5 and 4), CO2-sensors and water-tension sensors (WatermarkR) were installed in 6 cm soil depth. The results show a low variance of [CO2] in the undisturbed soil with a long term mean from May to June 2014 between 0.2 and 0.5 % [CO2] in both areas. In the wheel tracks [CO2] was consistently higher. The long term mean [CO2] in the 8-year-old-wheel track in test area 1 is 5 times higher than in the reference soil and shows a high variation (mean=2.0 %). The 18-year-old wheel track shows a long-term mean of 1.2 % [CO2]. Furthermore, there were strong fluctuations of [CO2] in the wheel tracks corresponding to precipitation and humidity. Similar results were yielded with single measurements during the vegetation period using a portable

  20. Variation of radon-222 concentration in exposure systems air under different conditions of exposure

    NASA Astrophysics Data System (ADS)

    Mamoon, A.; Abdul-Fattah, A. A.; Qari, T. M.

    1994-07-01

    Simplified, laboratory scale systems, namely ordinary laboratory desiccators and cylindrical containers were tested with regard to their reliability as exposure systems for determining certain parameters of radon emanation from locally obtained crushed granite rock samples. The samples were placed inside the exposure systems. Activity concentration of emanated radon in the exposure systems air increased with increase of mass of granite sample in the desiccator and with length of the exposure period. Activity concentration of radon was high near the granitic source but decreased with vertical distance from it when the exposure system was semiclosed but activity was homogeneous when the system was completely closed. The cylindrical exposure system was used in assessing Ra-226 content in some crushed granitic samples identified as altered alkali granite and found to be: 0.024 Bq g-1 (0.65 pCig-1). Rn-222 emanation rate from the same samples was: 0.013 Bq m-2 s-1 (0.34 pCi m-2 s-1). Saturation density thickness for a mixed sample of pure and alkali granites was found to be 116 g cm-2. The results agree in general with reported observations and support the reliability of the exposure systems used.

  1. Low pCO2 Air-Polarized CO2 Concentrator Development

    NASA Technical Reports Server (NTRS)

    Schubert, Franz H.

    1997-01-01

    Life Systems completed a Ground-based Space Station Experiment Development Study Program which verifies through testing the performance and applicability of the electrochemical Air-Polarized Carbon Dioxide Concentrator (APC) process technology for space missions requiring low (i.e., less than 3 mm Hg) CO2 partial pressure (pCO2) in the cabin atmosphere. Required test hardware was developed and testing was accomplished at an approximate one-person capacity CO2 removal level. Initially, two five-cell electrochemical modules using flight-like 0.5 sq ft cell hardware were tested individually, following by their testing at the integrated APC system level. Testing verified previously projected performance and established a database for sizing of APC systems. A four person capacity APC system was sized and compared with four candidate CO2 removal systems. At its weight of 252 lb, a volume of 7 cu ft and a power consumption of 566 W while operating at 2.2 mm Hg pCO2, the APC was surpassed only by an Electrochemical Depolarized CO2 Concentrator (EDC) (operating with H2), when compared on a total equivalent basis.

  2. Removal of low-concentration BTX in air using a combined plasma catalysis system.

    PubMed

    Fan, X; Zhu, T L; Wang, M Y; Li, X M

    2009-06-01

    The behavior of non-thermal plasma (NTP) and combined plasma catalysis (CPC) was investigated for removal of low-concentration benzene, toluene and p-xylene (BTX mixture) in air using a link tooth wheel-cylinder plasma reactor. Combining NTP with MnO(x)/Al(2)O(3) catalyst after the discharge zone (CPC) significantly promoted BTX conversion and improved the energy efficiency. For a specific input energy (SIE) of 10 JL(-1), the conversion of benzene, toluene and p-xylene reached 94%, 97% and 95%, respectively. The introduction of MnO(x)/Al(2)O(3) catalyst also moved the BTX conversion towards total oxidation and reduced the emission of O(3) and NO(2) as compared to NTP alone. For an SIE of 10 JL(-1), the O(3) outlet concentration decreased from 46.7 for NTP alone to 1.9 ppm for CPC, while the NO(2) emission correspondingly decreased from 1380 to 40 ppb.

  3. Effect of chimneys on indoor air concentrations of PM 10 and benzo[a]pyrene in Xuan Wei, China

    NASA Astrophysics Data System (ADS)

    Tian, Linwei; Lan, Qing; Yang, Dong; He, Xingzhou; Yu, Ignatius T. S.; Hammond, S. Katharine

    This paper reports the effect of chimneys in reducing indoor air pollution in a lung cancer epidemic area of rural China. Household indoor air pollution concentrations were measured during unvented burning (chimneys blocked) and vented burning (chimneys open) of bituminous coal in Xuan Wei, China. Concentrations of particulate matter with an aerodynamic diameter of 10 μm or less (PM 10) and of benzo[a]pyrene (BaP) were measured in 43 homes during normal activities. The use of chimneys led to significant decreases in indoor air concentrations of particulate matter with an aerodynamic diameter of 10 μm or less (PM 10) by 66% and of benzo[a]pyrene (BaP) by 84%. The average BaP content of PM 10 also decreased by 55% with the installation of a chimney. The reduction of indoor pollution levels by the installation of a chimney supports the epidemiology findings on the health benefits of stove improvement. However, even in the presence of a chimney, the indoor air concentrations for both PM 10 and BaP still exceeded the indoor air quality standards of China. Movement up the energy ladder to cleaner liquid or gaseous fuels is probably the only sustainable indoor air pollution control measure.

  4. Air pollutants in rural homes in Guizhou, China - Concentrations, speciation, and size distribution

    NASA Astrophysics Data System (ADS)

    Wang, Shuxiao; Wei, Wei; Li, Du; Aunan, Kristin; Hao, Jiming

    2010-11-01

    Several types of fuels, including coal, fuel wood, and biogas, are commonly used for cooking and heating in Chinese rural households, resulting in indoor air pollution and causing severe health impacts. In this paper, we report a study monitoring multiple pollutants including PM 10, PM 2.5, CO, CO 2, and volatile organic compounds (VOCs) from fuel combustion at households in Guizhou province of China. The results showed that most pollutants exhibited large variability for different type of fuels except for CO 2. Among these fuels, wood combustion caused the most serious indoor air pollution, with the highest concentrations of particulate matters (218˜417 μg m -3 for PM 10 and 201˜304 μg m -3 for PM 2.5), and higher concentrations of CO (10.8 ± 0.8 mg m -3) and TVOC (about 466.7 ± 337.9 μg m -3). Coal combustion also resulted in higher concentrations of particulate matters (220˜250 μg m -3 for PM 10 and 170˜200 μg m -3 for PM 2.5), but different levels for CO (respectively 14.5 ± 3.7 mg m -3 for combustion in brick stove and 5.5 ± 0.7 mg m -3 for combustion in metal stove) and TVOC (170 mg m -3 for combustion in brick stove and 700 mg m -3 for combustion in metal stove). Biogas was the cleanest fuel, which brought about the similar levels of various pollutants with the indoor case of non-combustion, and worth being promoted in more areas. Analysis of the chemical profiles of PM 2.5 indicated that OC and EC were dominant components for all fuels, with the proportions of 30˜48%. A high fraction of SO 42- (31˜34%) was detected for coal combustion. The cumulative percentages of these chemical species were within the range of 0.7˜1.3, which was acceptable for the assessment of mass balance.

  5. Effects of water-contaminated air on blowoff limits of opposed jet hydrogen-air diffusion flames

    NASA Technical Reports Server (NTRS)

    Pellett, Gerald L.; Jentzen, Marilyn E.; Wilson, Lloyd G.; Northam, G. Burton

    1988-01-01

    The effects of water-contaminated air on the extinction and flame restoration of the central portion of N2-diluted H2 versus air counterflow diffusion flames are investigated using a coaxial tubular opposed jet burner. The results show that the replacement of N2 contaminant in air by water on a mole for mole basis decreases the maximum sustainable H2 mass flow, just prior to extinction, of the flame. This result contrasts strongly with the analogous substitution of water for N2 in a relatively hot premixed H2-O2-N2 flame, which was shown by Koroll and Mulpuru (1986) to lead to a significant, kinetically controlled increase in laminar burning velocity.

  6. Concentrations of legacy and emerging flame retardants in air and soil on a transect in the UK West Midlands.

    PubMed

    Drage, Daniel S; Newton, Seth; de Wit, Cynthia A; Harrad, Stuart

    2016-04-01

    Passive air samples were collected monthly for 6 months from 8 sites along a transect of Birmingham, United Kingdom between June 2012 and January 2013. Soil samples were collected once at each site. Average concentrations of BDE-209, ΣPBDEs17:183 and ΣPBDEs in ambient air were 150, 49, and 180 pg m(-3), respectively. Atmospheric concentrations of PBDEs were negatively correlated with distance from the city centre, exhibiting an "urban pulse". The average ΣHBCDD air concentration was 100 pg m(-3), however concentrations were not correlated with distance from the city centre. Several emerging flame retardants (EFRs) were identified in air and/or soil samples: 2,3,4,5-tetrabromo-bis(2-ethylhexyl) phthalate (BEH-TEBP), 1,2-dibromo-4-(1,2 dibromoethyl)cyclohexane (TBECH or DBE-DBCH), allyl 2,4,6-tribromophenyl ether (ATE), 2-bromoallyl 2,4,6-tribromophenyl ether (BATE), decabromodiphenyl ethane (DBDPE), and dechlorane plus (DP or DDC-CO). Average concentrations of BDE-209, ΣPBDEs17:183 and ΣPBDEs in soil were 11, 3.6, and 15 ng g(-1) soil organic matter. PBDE concentrations in soil were higher at sites closest to the city centre, however correlations with distance from the city centre were not significant. BDEs-47 and -99 contributed more to ΣPBDEs in soil samples than air samples, but in both, the predominant congener was BDE-209. BATE was more abundant in air than soil but ATE was abundant in soil but not air. PMID:26807939

  7. Effects of air current speed, light intensity and co2 concentration on photosynthesis and transpiration of plant leaves

    NASA Astrophysics Data System (ADS)

    Kitaya, Y.; Tsuruyama, J.; Shibuya, T.; Kiyota, M.

    To obtain basic data for adequate air circulation to promote gas exchange and growth of plants in closed plant culture modules in bioregenerative life support systems in space, the effects of air current speeds less than 0.8 m s-1 on transpiration (Tr) and net photosynthetic rates (Pn) of sweetpotato and barley leaves were determined using a leaf chamber method under different photosynthetic photon flux densities (PPFDs) and CO_2 concentrations. The air current speed inside the leaf chamber was controlled by controlling the input voltages for an air circulation fan. The leaf surface boundary layer resistance was determined by the evaporation rate of wet paper and the water vapor pressure difference between the paper and surrounding air in the leaf chamber. The Tr and Pn of leaves rapidly increased as the air current speed increased from 0.01 to 0.1 m s-1 and gradually increased from 0.1 to 0.8 m s-1. These changes are correspondent to the change of the leaf surface boundary layer resistance. The depression of Tr by low air current speeds was greater than that of Pn. Tr and Pn decreased by 0.5 and 0.7 times, respectively, as the air current speed decreased from 0.8 to 0.01 m s-1. The depressions of Tr and Pn by low air current speeds were most notable at PPFDs of 500 and 250 μmol m-2 s-1, respectively. The air current speeds affected Tr and Pn at a CO_2 concentration of 700 μmol mol-1 as well as at 400 μmol mol-1. The results confirmed the importance of controlling air movement for enhancing Tr and Pn under the relatively high PPFD and elevated CO_2 levels likely in plant culture systems in space.

  8. Influence of the meteorological parameters on CFCs and SF6 concentration in the air of Krakow, Poland

    NASA Astrophysics Data System (ADS)

    Bielewski, Jarosław; Najman, Joanna; Śliwka, Ireneusz; Bartyzel, Jakub; Rosiek, Janusz

    2013-04-01

    key words: gas chromatography, trace gases, CFCs and SF6 measurements in urban area. Halogenated compounds (chlorofluorocarbons-CFCs), both natural and industrial, so-called freons, currently exist as trace gases in the entire human environment. The CFCs cause ozone depletion in the stratosphere. Moreover CFCs and SF6 take part in intensification of the greenhouse effect. The decisions of the Vienna Convention (1985) and of the Montreal Protocol (1987) limited the world production level of CFCs in the year 1989 at least 35% after 2004, 90% after 2015 and total reduction after year 2030. On account of international agreements, the measurements of CFCs and SF6 in air were started. Measurement "clean" stations were situated at places outside of urban areas influence and gathered on world program - AGAGE (Advanced Global Atmospheric Gases Experiment). One of these stations is Mace Head (Ireland, 53o N, 10o W), which participates in AGAGE since 1987 [1] and in European InGOS (Integrated non-CO2 Greenhouse gas Observing System) program since 2011. Similar research is also conducted in Central Europe, in urban area of Krakow (Poland, 50o N, 19o E) since 1997. The work discusses results from 15 years of concentration measurements (in the years 1997-2012) of selected halocarbons and SF6 in Krakow. To obtain concentrations of measured compounds the mathematical procedure has been used, where concentrations were calculated using a five points Lagrange's interpolation method. Using temporary measurement data were determined daily arithmetic means and their standard deviations. Based on these data, efficiency of Montreal Protocol legislation, implemented in Poland (The Journal of Laws No. 52) could be assessed [2]. Additionally cut-off filtration method was used to estimate trend of the base line of individual air pollutant. Rejected exceedances of base lines were corelated with meteorological characteristics of Krakow region to evaluate possible sources of pollution. The

  9. Concentration, temperature, and density in a hydrogen-air flame by excimer-induced Raman scattering

    NASA Technical Reports Server (NTRS)

    Wehrmeyer, Joseph A.; Bowling, John M.; Pitz, Robert W.

    1988-01-01

    Single-pulse, vibrational Raman scattering (VRS) is an attractive laser diagnostic for the study of supersonic hydrogen-air combustion. The VRS technique gives a complete thermodynamic description of the gas mixture at a point in the reacting flow. Single-pulse, vibrational Raman scattering can simultaneously provide independent measurements of density, temperature, and concentration of each major species (H2, H2O, O2 and N2) in a hydrogen/air turbulent combustor. Also the pressure can be calculated using the ideal gas law. However, single-pulse VRS systems in current use for measurement of turbulent combustion have a number of shortcomings when applied to supersonic flows: (1) slow repetition rate (1 to 5 Hz), (2) poor spatial resolution (0.5x0.3x0.3 cu mm), and (3) marginal time resolution. Most of these shortcomings are due to the use of visible wavelength flash-lamp pumped dye lasers. The advent of UV excimer laser allows the possibility of dramatic improvements in the single-pulse, vibrational Raman scattering. The excimer based VRS probe will greatly improve repetition rate (100 to 500 Hz), spatial resolution (0.1x0.1x0.1 cu mm) and time resolution (30ns). These improvements result from the lower divergence of the UV excimer, higher repetition rate, and the increased Raman cross-sections (15 to 20 times higher) at ultra-violet (UV) wavelengths. With this increased capability, single-pulse vibrational Raman scattering promises to be an ideal non-intrusive probe for the study of hypersonic propulsion flows.

  10. Effect of salt of various concentrations on liquid limit, and hydraulic conductivity of different soil-bentonite mixtures

    NASA Astrophysics Data System (ADS)

    Mishra, Anil Kumar; Ohtsubo, Masami; Li, Loretta Y.; Higashi, Takahiro; Park, Junboum

    2009-05-01

    Effect of the various concentrations of NaCl and CaCl2 on the four different soil-bentonite mixtures has been evaluated. The results show that the liquid limit of the mixtures decreases with an increase in the salt concentration. Liquid limit decreased significantly with an increase in CaCl2 concentration from 0 to 0.1 N. However, a further increase in the concentration did not produce any significant decrease in liquid limit. A quite opposite trend was observed for the NaCl solution. An increase in NaCl concentration from 0 to 0.1 N did not produce any major decrease in the liquid limit, but a further increase in concentration from 0.1 to 1 N decreased the liquid limit significantly. Consolidation tests were carried out on the mixtures to evaluate the effect of mineralogical composition of the bentonite on the hydraulic conductivity ( k) of the mixture in the presence of various salts concentrations. The k for any mixtures was found to be decreasing with decrease in the salt concentration. At relatively low concentration, Ca2+ had more effect on the k in comparison to the same concentration of Na+. However, at 1 N of NaCl and CaCl2 almost an equal value of k was observed. A comparison of the performance of four bentonites showed that the mixture with bentonite having highest exchangeable sodium percentage (ESP) exhibited the lowest k when permeated with de-ionized (DI) water, however, k increased with an increase in the salt concentration. Similarly, mixture with a bentonite of lower ESP exhibited a higher k with DI water but with the increase in the salt concentration alteration in the k, compared to all other mixtures, was relatively less.

  11. Limiter

    DOEpatents

    Cohen, S.A.; Hosea, J.C.; Timberlake, J.R.

    1984-10-19

    A limiter with a specially contoured front face is provided. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution. This limiter shape accommodates the various power scrape-off distances lambda p, which depend on the parallel velocity, V/sub parallel/, of the impacting particles.

  12. Comparison of indoor and outdoor concentrations of CO at a public school. Evaluation of an indoor air quality model

    NASA Astrophysics Data System (ADS)

    Chaloulakou, A.; Mavroidis, I.

    A field study was carried out to investigate the internal and external carbon monoxide (CO) concentration levels of a public school building in Athens, Greece. Simultaneous measurements of indoor and outdoor CO concentrations were conducted using a non-dispersive infrared analyzer. Measurements of mean hourly CO concentrations inside and outside the sampling room were conducted on a 24-h basis for 13 consecutive days during May and June 1999 and for 14 consecutive days during December 1999. The aim of the study was to investigate the attenuation pattern of external pollution levels within the building. The diurnal concentration variations reported for different days during the week show that indoor CO concentrations are in general lower than the respective outdoor levels, and that the morning peaks of indoor concentrations show a delay of 1 h or less compared to the morning peaks of outdoor concentrations. The measured indoor to outdoor concentration ratios show a seasonal variation. An indoor air quality model for the prediction of indoor concentration levels developed by Hayes (J. Air Pollut. Control Assoc. 39 (11) (1989) 1453; J. Air Waste Manage. Assoc. 41 (2) (1991) 161) is coded as a computer program and evaluated using the experimental data. The model results are in good agreement with the indoor concentration measurements, although in some cases the model cannot respond adequately to sharp outdoor concentration changes. The ratio between measured and predicted daily maximum indoor concentration ranges between 0.88 and 1.23. The regression curve between predicted by the model and measured hourly indoor concentrations, for a continuous period of 96 h, has a slope of 0.64 and a coefficient of determination ( R2) of 0.69.

  13. Sooting Limits Of Diffusion Flames With Oxygen-Enriched Air And Diluted Fuel

    NASA Technical Reports Server (NTRS)

    Sunderland, P. B.; Urban, D. L.; Stocker, D. P.; Chao, B. H.; Axelbaum, R. L.

    2003-01-01

    Oxygen-enhanced combustion permits certain benefits and flexibility that are not otherwise available in the design of practical combustors, as discussed by Baukal. The cost of pure and enriched oxygen has declined to the point that oxygen-enhanced combustion is preferable to combustion in air for many applications. Carbon sequestration is greatly facilitated by oxygen enrichment because nitrogen can be eliminated from the product stream. For example, when natural gas (or natural gas diluted with CO2) is burned in pure oxygen, the only significant products are water and CO2. Oxygen-enhanced combustion also has important implications for soot formation, as explored in this work. We propose that soot inception in nonpremixed flames requires a region where C/O ratio, temperature, and residence time are above certain critical values. Soot does not form at low temperatures, with the threshold in nonpremixed flames ranging from about 1250-1650 K, a temperature referred to here as the critical temperature for soot inception, Tc. Soot inception also can be suppressed when residence time is short (equivalently, when the strain rate in counterflow flames is high). Soot induction times of 0.8-15 ms were reported by Tesner and Shurupov for acetylene/nitrogen mixtures at 1473 K. Burner stabilized spherical microgravity flames are employed in this work for two main reasons. First, this configuration offers unrestricted control over convection direction. Second, in steady state these flames are strain-free and thus can yield intrinsic sooting limits in diffusion flames, similar to the way past work in premixed flames has provided intrinsic values of C/O ratio associated with soot inception limits.

  14. Experimental study of lean flammability limits of methane/hydrogen/air mixtures in tubes of different diameters

    SciTech Connect

    Shoshin, Y.L.; Goey, L.P.H. de

    2010-04-15

    Lean limit flames in methane/hydrogen/air mixtures propagating in tubes of internal diameters (ID) of 6.0, 8.9, 12.3, 18.4, 25.2, 35.0, and 50.2 mm have been experimentally studied. The flames propagated upward from the open bottom end of the tube to the closed upper end. The content of hydrogen in the fuel gas has been varied in the range 0-40 mol%. Lean flammability limits have been determined; flame shapes recorded and the visible speed of flame propagation measured. Most of the observed limit flames in tubes with diameters in the range of 8.9-18.4 mm had enclosed shape, and could be characterized as distorted or spherical flame balls. The tendency was observed for mixtures with higher hydrogen content to form smaller size, more uniform flame balls in a wider range of tube diameters. At hydrogen content of 20% or more in the fuel gas, limit flames in largest diameters (35.0 mm and 50.2 mm ID) tubes had small, compared to the tube diameter, size and were ''lens''-shaped. ''Regular'' open-front lean limit flames were observed only for the smallest diameters (6.0 mm and 8.9 mm) and largest diameters (35.0 and 50.2 mm ID), and only for methane/air and (90% CH{sub 4} + 10% H{sub 2})/air mixtures, except for 6 mm ID tube in which all limit flames had open front. In all experiments, except for the lean limit flames in methane/air and (90% CH{sub 4} + 10% H{sub 2})/air mixtures in the 8.9 mm ID tube, and all limit flames in 6.0 mm ID tube, visible flame speeds very weakly depended on the hydrogen content in the fuel gas and were close to- or below the theoretical estimate of the speed of a rising hot bubble. This observation suggests that the buoyancy is the major factor which determines the visible flame speed for studied limit flames, except that last mentioned. A decrease of the lean flammability limit value with decreasing the tube diameter was observed for methane/air and (90% CH{sub 4} + 10% H{sub 2})/air mixtures for tubes having internal diameters in the range

  15. 40 CFR 63.1444 - What emissions limitations and work practice standards must I meet for my copper concentrate...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... practice standards must I meet for my copper concentrate dryers, smelting furnaces, slag cleaning vessels... limitations and work practice standards must I meet for my copper concentrate dryers, smelting furnaces, slag... measured using the test methods specified in § 63.1450(a). (b) Smelting furnaces. For each smelting...

  16. Liquid products from oxidative thermal treatment of oil sludge with different oxygen concentrations of air.

    PubMed

    Shie, J L; Chang, C Y; Lin, J P; Le, D J; Wu, C H

    2001-01-01

    Oxidative thermal treatment of oil sludge with different oxygen concentrations of air by using a dynamic thermogravimetric (TG) reaction system is investigated. The experimental conditions employed are: gas flow rate of 50 cm3/min (value at 298 K) for 300 mg dry waste, a constant heating rate of 5.2 K/min, the oxygen concentrations in air of 1.09, 8.62 and 20.95 vol. % O2, and the temperature (T) range of 378-873 K. From the experimental results, the residual mass fractions (M) are about 78.95, 28.49, 8.77 and 4.13 wt. % at the oxidative T of 563, 713, 763 and 873 K for the case with 20.95 vol. % O2, respectively. The values of M with 8.62 and 1.09 vol. % O2 at T of 873 K are 4.87 and 9.44 wt. %, respectively. The distillation characteristics of the oil portion of liquid products (condensates of gas at 298 K) from the oxidative thermal treatment of oil sludge with 20.95 vol. % O2 at T of 378-873 K is close to those of commercial gasoline. Nevertheless, the liquid product contains a large amount of water. The distillation characteristics of the oil portions of liquid products with 8.62 and 1.09 vol. % O2 at T of 378-873 K are close to those of diesel and fuel oils, respectively. The oil quality with 8.62 vol. % O2 is better than that with 1.09 vol. % O2. However, the liquid product with 8.62 vol. % O2 still contains a large amount of water; nonetheless, that with 1.09 vol. % O2 is with negligible water. Compared with the oil product of nitrogen pyrolysis, the oil quality with 1.09 vol. % O2 is better. Certainly, low oxygen conditions (i.e. 1.09 vol. % O2) not only accelerate the thermal reaction of oil sludge, but also at the same time avoid or reduce the production of water. Further, from the analysis of benzene (B), ethylbenzene (E), toluene (T) and iso-xylene (X) concentrations of the oil portion of liquid products, the BETX concentrations of oil with 20.95 vol. % O2 are higher than those with 8.62 and 1.09 vol. % O2. The yields of liquid products with 20.95, 8

  17. Influences of ambient air PM₂.₅ concentration and meteorological condition on the indoor PM₂.₅ concentrations in a residential apartment in Beijing using a new approach.

    PubMed

    Han, Yang; Qi, Meng; Chen, Yilin; Shen, Huizhong; Liu, Jing; Huang, Ye; Chen, Han; Liu, Wenxin; Wang, Xilong; Liu, Junfeng; Xing, Baoshan; Tao, Shu

    2015-10-01

    PM2.5 concentrations in a typical residential apartment in Beijing and immediately outside of the building were measured simultaneously during heating and non-heating periods. The objective was to quantitatively explore the relationship between indoor and outdoor PM2.5 concentrations. A statistical method for predicting indoor PM2.5 concentrations was proposed. Ambient PM2.5 concentrations were strongly affected by meteorological conditions, especially wind directions. A bimodal distribution was identified during the heating season due to the frequent and rapid transition between severe pollution events and clean days. Indoor PM2.5 concentrations were significantly correlated with outdoor PM2.5 concentrations but with 1-2 h delay, and the differences can be explained by ambient meteorological features, such as temperature, humidity, and wind direction. These results indicate the potential to incorporate indoor exposure features to the regional air quality model framework and to more accurately estimate the epidemiological relationship between human mortality and air pollution exposure.

  18. Sulfate concentrations as an indicator of ambient particulate matter air pollution for health risk evaluations.

    PubMed

    Lippmann, M; Thurston, G D

    1996-01-01

    Retrospective population studies that have compared regression coefficients for mortality and morbidity for sulfate (SO4(2-), fine particles (PM2.5; aerodynamic diameter < 2.5 microns), thoracic particles (PM10; aerodynamic diameter < 10 microns), and total suspended particulates (TSP; undefined and variable upper cut-size) generally have found SO4(2-) concentrations to be correlated with effects as well as or better than PM2.5. In addition, both SO4(2-) and PM2.5 have yielded somewhat stronger associations with adverse health effects than PM10, and much stronger associations than TSP. Sulfate has advantages over PM2.5 for retrospective epidemiology, at least in the United States, because considerably more data on sulfate have been collected in recent decades, and there is a broader epidemiological database in the literature for comparison to other studies. While SO4(2-), per se, is an unlikely causal factor for mortality or morbidity, it often is correlated closely with variations in the strong acid component of ambient particulate matter (H+) and PM2.5 concentrations (especially in summer), which are more likely causal factors. A detailed analysis of the SO4(2-) epidemiological database is presented in this paper. In addition, drawing on our substantial archives of SO4(2-) and H+ data, we show that SO4(2-) and H+ correlate, both spatially and over time, in the eastern United States. We demonstrate the utility of SO4(2-) as a useful surrogate for ambient PM2.5 and H+ in epidemiological studies and as an index of PM exposure in ambient air quality guidelines and standards.

  19. Limiter

    DOEpatents

    Cohen, Samuel A.; Hosea, Joel C.; Timberlake, John R.

    1986-01-01

    A limiter with a specially contoured front face accommodates the various power scrape-off distances .lambda..sub.p, which depend on the parallel velocity, V.sub..parallel., of the impacting particles. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution.

  20. Assessing the impact of the forthcoming decrease in diesel exhaust particulate matter emissions on air quality: implications for black carbon concentrations in ambient air

    NASA Astrophysics Data System (ADS)

    González, Y.; Rodríguez, S.; Cuevas, E.; Ramos, R.; Abreu-Afonso, J.; Baldasano, J. M.

    2009-04-01

    Forthcoming regulations (e.g. EURO 5 and EURO 6) are planned to reduce particulate matter emissions (PM) in the exhaust of forthcoming vehicles. In this study we assess the impact of such reduction in the diesel PM exhaust emissions on the urban ambient air PM concentrations. This has been done by studying the relationship between black carbon (BC) and carbon monoxide (CO) in urban ambient air and in the exhaust of current and forthcoming vehicles. The slope of the BC-vs-CO linear relationship is mainly affected by the percentage (%) of diesel automobiles in the urban vehicles fleet. This slope is a better indicator of the diesel PM emissions than bulk BC concentrations in urban ambient air. BC-vs-CO slopes within the range 1-3 and 7-14 ngBC/µgCO are typically observed in urban areas with low (<25%) and high (≥50%) proportions of diesel-fuel consumption for on road transportation, respectively. The entry into force of forthcoming regulations will decrease the BC-vs-CO slope in urban ambient air from about 10 to 5 ngBC/µgCO in the next decade, according to calculations based on the current data on diesel vehicles in urban fleets in Spanish cities. However, this will not necessary prompt a significant decrease in the urban BC concentrations if road traffic volume follows the increasing trend of the last decade. The results of this study shows that the analysis of the BC-vs-CO slope trend in ambient air is an useful tool for understanding the involvement "of the changes in the vehicle exhaust emissions rates" and "of the changes in the road traffic volume" in the BC and PMx trends in urban ambient air.

  1. Solving widespread low-concentration VOC air pollution problems: Gas-phase photocatalytic oxidation answers the needs of many small businesses

    SciTech Connect

    Lyons, C; Turchi, C; Gratson, D

    1995-04-01

    Many small businesses are facing new regulations under the 1990 Amendments to the Clean Air Act. Regulators, as well as the businesses themselves, face new challenges to control small point-source air pollution emissions. An individual business-such as a dry cleaner, auto repair shop, bakery, coffee roaster, photo print shop, or chemical company-may be an insignificant source of air pollution, but collectively, the industry becomes a noticeable source. Often the businesses are not equipped to respond to new regulatory requirements because of limited resources, experience, and expertise. Also, existing control strategies may be inappropriate for these businesses, having been developed for major industries with high volumes, high pollutant concentrations, and substantial corporate resources. Gas-phase photocatalytic oxidation (PCO) is an option for eliminating low-concentration, low-flow-rate emissions of volatile organic compounds (VOCs) from small business point sources. The advantages PCO has over other treatment techniques are presented in this paper. This paper also describes how PCO can be applied to specific air pollution problems. We present our methodology for identifying pollution problems for which PCO is applicable and for reaching the technology`s potential end users. PCO is compared to other gas-phase VOC control technologies.

  2. BTEX air concentrations and self-reported common health problems in gasoline sellers from Cotonou, Benin.

    PubMed

    Tohon, Honesty Gbèdolo; Fayomi, Benjamin; Valcke, Mathieu; Coppieters, Yves; Bouland, Catherine

    2015-01-01

    To examine the relation between BTEX exposure levels and common self-reported health problems in 140 gasoline sellers in Cotonou, Benin, a questionnaire documenting their socioeconomic status and their health problems was used, whereas 18 of them went through semi-directed qualitative individual interviews and 17 had air samples taken on their workplace for BTEX analysis. Median concentrations for BTEX were significantly lower on official (range of medians: 54-207 μg/m³, n = 9) vs unofficial (148-1449 μg/m³, n = 8) gasoline-selling sites (p < 0.05). Self-reported health problems were less frequently reported in sellers from unofficial vs official selling sites (p < 0.05), because, as suggested by the semi-directed interviews, of their fear of losing their important, but illegal, source of income. Concluding, this study has combined quantitative and qualitative methodological approaches to account for the complex socioeconomic and environmental conditions of the investigated sellers, leading to their, in some cases, preoccupying BTEX exposure.

  3. Radical Concentrations and Prompt NO Formation in Hydrocarbon-Air Premixed Flames

    NASA Astrophysics Data System (ADS)

    Matusi, Yasuji; Yuuki, Akimasa

    1985-05-01

    Hydroxyl radical concentrations in laminar, premixed CH4-air flat-flames were measured by a conventional absorption method in the flame temperature range T{=}2200-1700 K. The OH mole fractions in the reaction zone POH were found to be insensitive to the flame temperature and the maximum POH to be about 6× 10-3 at T{=}2000 K in a stoichiometric flame. The rate constant for the prompt NO formation, CH+N2→HCN+N\\dashrightarrow2NO (4), is modified as k4{=}1.2× 1012\\exp (-13600/RT) by the relation between the amount of prompt NO and the saturation ion current Is. It is also shown from the measurements of NOx, unburnt hydrocarbons H.C., and Is, that the chemical kinetics are not significantly influenced by the flame temperature, and NO emission is reduced by reactions among NO, H.C., and N-containing intermediate species in low-temperature flames, even in stoichiometric and fuel-lean mixtures.

  4. [Volatile organic compounds concentrations and sources inside new air-conditioned bus].

    PubMed

    You, Ke-Wei; Ge, Yun-Shan; Qian, Yi-Xin; Liu, Wei; Feng, Bo; Zhang, Yan-Ni; Ning, Zhan-Wu; Hu, Bin; Zhao, Shou-Tang

    2008-05-01

    The distributing profile and concentration level inside new air-conditioned buses with 53 seats have been determined using the method of thermal desorption-capillary GC/MS under vehicle static conditions. Compounds were identified from their mass spectral data by using US National Institute of Standards and Technology (NIST02). The total numbers of identified components were 33 inside buses, including alkenes (15,45.4%), aromatic compounds (9,27.3%), alcohols (4,12.1%), ketones (3,9.1%) and esters (2,6.1%), especially in the range of C6-C10. The top 5 compounds measured inside buses were decane (8.01 mg/m3), 3-methylhexane (7.10 mg/m3), heptane (5.10 mg/m3), isoheptane (4.20 mg/m3) and 1-Methyl-3-ethylbenzene (3.56 mg/m3), and total volatile organic compounds (TVOC) > 52.5 mg/m3. The main sources of in-vehicle hydrocarbons and aromatic compounds comes from cabin components and interior trim materials (e.g., sealants, carpets, adhesives, paints, leather, plastics, PU foam and PE foam) that may retain certain VOCs during manufacturing, and/or emit these compounds over an extended period of time from off-gassing, aging-related breakdown products, heating/cooling and so on.

  5. Evaluation of Ultra-Violet Photocatalytic Oxidation (UVPCO) forIndoor Air Applications: Conversion of Volatile Organic Compounds at LowPart-per-Billion Concentrations

    SciTech Connect

    Hodgson, Alfred T.; Sullivan, Douglas P.; Fisk, William J.

    2005-09-30

    most reactive chemical classes with conversion efficiencies often near or above 70% at the low flow rate and near 40% at the high flow rate. Ketones and terpene hydrocarbons were somewhat less reactive. The relative VOC conversion rates are generally favorable for treatment of indoor air since many contemporary products used in buildings employ oxygenated solvents. A commercial UVPCO device likely would be installed in the supply air stream of a building and operated to treat both outdoor and recirculated air. Assuming a recirculation rate comparable to three times the normal outdoor air supply rate, simple mass-balance modeling suggests that a device with similar characteristics to the study unit has sufficient conversion efficiencies for most VOCs to compensate for a 50% reduction in outdoor air supply without substantially impacting indoor VOC concentrations. Formaldehyde, acetaldehyde, acetone, formic acid, and acetic acid were produced in these experiments as reaction byproducts. No other significant byproducts were observed. A coupled steady-state mass balance model is presented and applied to VOC data from a study of a single office building. For the operating assumptions described above, the model estimated a three-fold increase in indoor formaldehyde and acetaldehyde concentrations. The outcome of this limited assessment suggests that evaluation of the potential effects of the operation of a UVPCO device on indoor concentrations of these contaminants is warranted. Other suggested studies include determining VOC conversion efficiencies in actual buildings and evaluating changes in VOC conversion efficiency as monoliths age with long-term operation.

  6. Effect of the implosion and demolition of a hospital building on the concentration of fungi in the air.

    PubMed

    Barreiros, Gloria; Akiti, Tiyomi; Magalhães, Ana Cristina Gouveia; Nouér, Simone A; Nucci, Marcio

    2015-12-01

    Building renovations increase the concentration of Aspergillus conidia in the air. In 2010, one wing of the hospital building was imploded due to structural problems. To evaluate the impact of building implosion on the concentration of fungi in the air, the demolition was performed in two phases: mechanical demolition of 30 m of the building, followed by implosion of the wing. Patients at high risk for aspergillosis were placed in protected wards. Air sampling was performed during mechanical demolition, on the day of implosion and after implosion. Total and specific fungal concentrations were compared in the different areas and periods of sampling, using the anova test. The incidence of IA in the year before and after implosion was calculated. The mean concentration of Aspergillus increased during mechanical demolition and on the day of implosion. However, in the most protected areas, there was no significant difference in the concentration of fungi. The incidence of invasive aspergillosis (cases per 1000 admissions) was 0.9 in the 12 months before, 0.4 during, and 0.5 in the 12 months after mechanical demolition (P > 0.05). Continuous monitoring of the quality of air and effective infection control measures are important to minimize the impact of building demolition. PMID:26449634

  7. Indoor air quality in the Karns research houses: baseline measurements and impact of indoor environmental parameters on formaldehyde concentrations

    SciTech Connect

    Matthews, T. G.; Fung, K. W.; Tromberg, B. J.; Hawthorne, A. R.

    1985-12-01

    Baseline indoor air quality measurements, a nine-month radon study, and an environmental parameters study examining the impact of indoor temperature (T) and relative humidity (RH) levels on formaldehyde (CH2O) concentrations have been performed in three unoccupied research homes located in Karns, Tennessee. Inter-house comparison measurements of (1) CH2O concentration, (2) CH20 emission rates from primary CH20 emission sources, (3) radon and radon daughter concentrations, and (4) air exchange rates indicate that the three homes are similar. The results of the nine-month radon study indicate indoor concentrations consistently below the EPA recommended level of 4 pCi/L. Evidence was found that crawl-space concentrations may be reduced using heat pump systems whose outdoor units circulate fresh air through the crawl-spaoe. The modeled results of the environmental parameters study indicate approximate fourfold increases in CH20 concentrations from 0.07 to 0.27 ppm for seasonal T and RH conditions of 20°C, 30% RH and 29°C, 80% RH, respectively. Evaluation of these environmental parameters study data with steady-state CH2O concentration models developed from laboratory studies of the environmental dependence of CH2O emissions from particleboard underlayment indicate good correlations between the laboratory and field studies.

  8. Limiting of microjoule femtosecond pulses in air-guided modes of a hollow photonic-crystal fiber

    SciTech Connect

    Konorov, S.O.; Serebryannikov, E.E.; Sidorov-Biryukov, D.A.; Bugar, I.; Chorvat, D. Jr.; Chorvat, D.; Bloemer, M.J.; Scalora, M.; Miles, R.B.; Zheltikov, A.M.

    2004-08-01

    Self-phase-modulation-induced spectral broadening of laser pulses in air-guided modes of hollow photonic-crystal fibers (PCFs) is shown to allow the creation of fiber-optic limiters for high-intensity ultrashort laser pulses. The performance of PCF limiters is analyzed in terms of elementary theory of self-phase modulation. Experiments performed with 100 fs microjoule pulses of 800 nm Ti:sapphire laser radiation demonstrate the potential of hollow PCFs as limiters for 10 MW ultrashort laser pulses and show the possibility to switch the limiting level of output radiation energy by guiding femtosecond pulses in different PCF modes.

  9. Comparing three vegetation monoterpene emission models to measured gas concentrations with a model of meteorology, air chemistry and chemical transport

    NASA Astrophysics Data System (ADS)

    Smolander, S.; He, Q.; Mogensen, D.; Zhou, L.; Bäck, J.; Ruuskanen, T.; Noe, S.; Guenther, A.; Aaltonen, H.; Kulmala, M.; Boy, M.

    2013-11-01

    Biogenic volatile organic compounds (BVOCs) are essential in atmospheric chemistry because of their chemical reactions that produce and destroy tropospheric ozone, their effects on aerosol formation and growth, and their potential influence on global warming. As one of the important BVOC groups, monoterpenes have been a focus of scientific attention in atmospheric research. Detailed regional measurements and model estimates are needed to study emission potential and the monoterpene budget on a global scale. Since the use of empirical measurements for upscaling is limited by many physical and biological factors such as genetic variation, temperature and light, water availability, seasonal changes, and environmental stresses, comprehensive inventories over larger areas are difficult to obtain. We applied the boundary layer-chemistry-transport model SOSA to investigate Scots pine (Pinus sylvestris) monoterpene emissions in a boreal coniferous forest at the SMEAR II site, Southern Finland. SOSA was applied to simulate monoterpene emissions with three different emission modules: the semi-empirical G95, MEGAN 2.04 with improved descriptions of temperature and light responses and including also carbonyl emissions, and a process-based model SIM-BIM. For the first time, the emission models included seasonal and diurnal variations in both quantity and chemical species of emitted monoterpenes, based on parameterizations obtained from field measurements. Results indicate that modelling and observations agreed reasonably well, and that the model can be used for investigating regional air chemistry questions related to monoterpenes. The predominant modelled monoterpene concentrations, α-pinene and Δ3-carene, are consistent with observations.

  10. Background concentrations of individual and total volatile organic compounds in residential indoor air of Schleswig-Holstein, Germany.

    PubMed

    Hippelein, Martin

    2004-09-01

    During a monitoring campaign concentrations of volatile organic compounds (VOCs) were measured in indoor air of 79 dwellings where occupants had not complained about health problems or unpleasant odour. Parameters monitored were the individual concentration of 68 VOCs and the total concentration of all VOCs inside the room. VOCs adsorbed by Tenax TA were then analysed by means of thermal desorption, gas chromatography and mass spectrometry. The analytical procedure and quantification was done according to the recommendation of the ECA-IAQ Working Group 13 which gave a definition of the total volatile organic compound (TVOC) concentration. Using this recommendation TVOC-concentrations ranged between 33 and 1600 microg m(-3) with a median of 289 microg m(-3). Compounds found in every sample and with the highest concentrations were 2-propanol, alpha-pinene and toluene. Save for a few samples, all concentrations measured have been a factor 2 to 10 lower, compared to data from similar studies. Only a few terpenes and aldehydes were found exceeding published reference data or odour threshold concentrations. However, it has been found that sampling and analysing methods do have a considerable impact on the results, making direct comparisons of studies somewhat questionable. 47% of all samples revealed concentrations exceeding the threshold value of 300 microg TVOC m(-3) set by the German Federal Environmental Agency as a target for indoor air quality. Using the TVOC concentration as defined in the ECA-IAQ methodology is instrumental in assessing exposure to VOCs and identifying sources of VOCs. The background concentrations determined in this study can be used to discuss and interpret target values for individual and total volatile organic compounds in indoor air.

  11. Laminar lean premixed methane/air combustion near the lean flammability limit using nanosecond repetitive pulsed discharge plasmas

    NASA Astrophysics Data System (ADS)

    Bak, Moon Soo; Do, Hyungrok; Mungal, Mark G.; Cappelli, Mark A.

    2011-10-01

    Gas chromatographic and temperature measurements have been carried out to investigate the extent of premixed methane/air combustion with the application of nanosecond repetitive pulsed discharges around the lean flammability limit for laminar flows. The results show that the discharges lead to the complete combustion when the equivalence ratio is above 0.54, but when the ratio is below the limit, the combustion is quenched at the downstream flow. To investigate the kinetics in detail, 2-D simulations of plasma-induced combustion have been conducted for methane/air mixtures at below and above the lean flammability limit. The simulations reveal that methane is mostly combusted in the discharge region since the discharge repetition timescale is much shorter than the species diffusion and advection timescales, and so the discharge serves more as a heat and radical source rather than a small combustor, to flame hold near the lean flammability limit.

  12. Seasonal variability of tritium and ion concentrations in rain at Kumamoto, Japan and back-trajectory analysis of air mass

    SciTech Connect

    Momoshima, N.; Sugihara, S.; Toyoshima, T.; Nagao, Y.; Takahashi, M.; Nakamura, Y.

    2008-07-15

    Tritium and major ion concentrations in rain were analyzed in Kumamoto (Japan)) between 2001 and 2006 to examine present tritium concentration and seasonal variation. The average tritium concentration was 0.36 {+-} 0.19 Bq/L (n=104) and higher tritium concentrations were observed in spring than the other seasons. Among the ions, non-sea-salt (nss) SO{sub 4}{sup 2}'- showed higher concentration in winter while other ions did not show marked increase in winter. Based on the back-trajectory analyses of air masses, the increase in tritium concentrations in spring arises from downward movement of naturally produced tritium from stratosphere to troposphere, while the increase of the nss-SO{sub 4}{sup 2-} concentrations in winter is due to long range transport of pollutants from China to Japan. (authors)

  13. Optimal Modeling of Urban Ambient Air Ozone Concentration Based on Its Precursors' Concentrations and Temperature, Employing Genetic Programming and Genetic Algorithm.

    PubMed

    Mousavi, Seyed Mahmoud; Husseinzadeh, Danial; Alikhani, Sadegh

    2014-04-01

    Efficient models are required to predict the optimum values of ozone concentration in different levels of its precursors' concentrations and temperatures. A novel model based on the application of a genetic programming (GP) optimization is presented in this article. Ozone precursors' concentrations and run time average temperature have been chosen as model's parameters. Generalization performances of two different homemade models based on genetic programming and genetic algorithm (GA), which can be used for calculating theoretical ozone concentration, are compared with conventional semi-empirical model performance. Experimental data of Mashhad city ambient air have been employed to investigate the prediction ability of properly trained GP, GA, and conventional semi-empirical models. It is clearly demonstrated that the in-house algorithm which is used for the model based on GP, provides better generalization performance over the model optimized with GA and the conventional semi-empirical ones. The proposed model is found accurate enough and can be used for urban air ozone concentration prediction.

  14. Nitric Oxide and Oxygen Air-Contamination Effects on Extinction Limits of Non-Premixed Hydrocarbon-Air Flames for a HIFiRE Scramjet

    NASA Technical Reports Server (NTRS)

    Pellett, Gerald L.; Dawson, Lucy C.; Vaden, Sarah N.; Wilson, Lloyd G.

    2009-01-01

    Unique nitric oxide (NO) and oxygen air-contamination effects on the extinction Flame Strength (FS) of non-premixed hydrocarbon (HC) vs. air flames are characterized for 7 gaseous HCs, using a new idealized 9.3 mm straight-tube Opposed Jet Burner (OJB) at 1 atm. FS represents a laminar strain-induced extinction limit based on cross-section-average air jet velocity, Uair, that sustains combustion of a counter jet of gaseous fuel just before extinction. Besides ethane, propane, butane, and propylene, the HCs include ethylene, methane, and a 64 mole-% ethylene / 36 % methane mixture, the writer s previously recommended gaseous surrogate fuel for HIFiRE scramjet tests. The HC vs. clean air part of the work is an extension of a May 2008 JANNAF paper that characterized surrogates for the HIFiRE project that should mimic the flameholding of reformed (thermally- or catalytically-cracked) endothermic JP-like fuels. The new FS data for 7 HCs vs. clean air are thus consolidated with the previously validated data, normalized to absolute (local) axial-input strain rates, and co-plotted on a dual kinetically dominated reactivity scale. Excellent agreement with the prior data is obtained for all 7 fuels. Detailed comparisons are also made with recently published (Univ. Va) numerical results for ethylene extinction. A 2009-revised ethylene kinetic model (Univ. Southern Cal) led to predicted limits within approx. 5 % (compared to 45 %, earlier) of this writer s 2008 (and present) ethylene FSs, and also with recent independent data (Univ. Va) obtained on a new OJB system. These +/- 5 % agreements, and a hoped-for "near-identically-performing" reduced kinetics model, would greatly enhance the capability for accurate numerical simulations of surrogate HC flameholding in scramjets. The measured air-contamination effects on normalized FS extinction limits are projected to assess ongoing Arc-Heater-induced "facility test effects" of NO production (e.g., 3 mole-%) and resultant oxygen

  15. Uncertainty-weighted time averaging of mercury vapour concentrations in ambient air: application to measurements in the United kingdom.

    PubMed

    Brown, Richard J C; Muhunthan, Dharsheni

    2011-02-03

    Uncertainty-weighted time averaging of total gaseous mercury concentrations in ambient air, with associated robust uncertainties, has been performed for concentrations measured by the U.K. Heavy Metals Monitoring Network between 2007 and 2009. The results have been compared with averages produced using standard time-averaging methods with a view to investigating the properties of the new method and whether it represents an improvement over current practice.

  16. Blocking of the water-lunar fines reaction by air and water concentration effects

    NASA Technical Reports Server (NTRS)

    Gammage, R. B.; Holmes, H. F.

    1975-01-01

    The elements of air, if adsorbed in conjunction with water vapor or liquid water, are able to impede severely the attack of lunar fines. Thus is explained the stability of lunar fines in moisture laden air, and their small solubility in liquid, aerated water. In the absence of air, liquid water is more effective than water vapor in attacking the grains; the channels formed are wider and the expansion of area is greater.

  17. Occurrence and Concentrations of Toxic VOCs in the Ambient Air of Gumi, an Electronics-Industrial City in Korea.

    PubMed

    Baek, Sung-Ok; Suvarapu, Lakshmi Narayana; Seo, Young-Kyo

    2015-08-05

    This study was carried out to characterize the occurrence and concentrations of a variety of volatile organic compounds (VOCs) including aliphatic, aromatic, halogenated, nitrogenous, and carbonyl compounds, in the ambient air of Gumi City, where a large number of electronics industries are found. Two field monitoring campaigns were conducted for a one year period in 2003/2004 and 2010/2011 at several sampling sites in the city, representing industrial, residential and commercial areas. More than 80 individual compounds were determined in this study, and important compounds were then identified according to their abundance, ubiquity and toxicity. The monitoring data revealed toluene, trichloroethylene and acetaldehyde to be the most significant air toxics in the city, and their major sources were mainly industrial activities. On the other hand, there was no clear evidence of an industrial impact on the concentrations of benzene and formaldehyde in the ambient air of the city. Overall, seasonal variations were not as distinct as locational variations in the VOCs concentrations, whereas the within-day variations showed a typical pattern of urban air pollution, i.e., increase in the morning, decrease in the afternoon, and an increase again in the evening. Considerable decreases in the concentrations of VOCs from 2003 to 2011 were observed. The reductions in the ambient concentrations were confirmed further by the Korean PRTR data in industrial emissions within the city. Significant decreases in the concentrations of benzene and acetaldehyde were also noted, whereas formaldehyde appeared to be almost constant between the both campaigns. The decreased trends in the ambient levels were attributed not only to the stricter regulations for VOCs in Korea, but also to the voluntary agreement of major companies to reduce the use of organic solvents. In addition, a site planning project for an eco-friendly industrial complex is believed to play a contributory role in improving

  18. Occurrence and Concentrations of Toxic VOCs in the Ambient Air of Gumi, an Electronics-Industrial City in Korea

    PubMed Central

    Baek, Sung-Ok; Suvarapu, Lakshmi Narayana; Seo, Young-Kyo

    2015-01-01

    This study was carried out to characterize the occurrence and concentrations of a variety of volatile organic compounds (VOCs) including aliphatic, aromatic, halogenated, nitrogenous, and carbonyl compounds, in the ambient air of Gumi City, where a large number of electronics industries are found. Two field monitoring campaigns were conducted for a one year period in 2003/2004 and 2010/2011 at several sampling sites in the city, representing industrial, residential and commercial areas. More than 80 individual compounds were determined in this study, and important compounds were then identified according to their abundance, ubiquity and toxicity. The monitoring data revealed toluene, trichloroethylene and acetaldehyde to be the most significant air toxics in the city, and their major sources were mainly industrial activities. On the other hand, there was no clear evidence of an industrial impact on the concentrations of benzene and formaldehyde in the ambient air of the city. Overall, seasonal variations were not as distinct as locational variations in the VOCs concentrations, whereas the within-day variations showed a typical pattern of urban air pollution, i.e., increase in the morning, decrease in the afternoon, and an increase again in the evening. Considerable decreases in the concentrations of VOCs from 2003 to 2011 were observed. The reductions in the ambient concentrations were confirmed further by the Korean PRTR data in industrial emissions within the city. Significant decreases in the concentrations of benzene and acetaldehyde were also noted, whereas formaldehyde appeared to be almost constant between the both campaigns. The decreased trends in the ambient levels were attributed not only to the stricter regulations for VOCs in Korea, but also to the voluntary agreement of major companies to reduce the use of organic solvents. In addition, a site planning project for an eco-friendly industrial complex is believed to play a contributory role in improving

  19. Determining the long-term effects of H₂S concentration, relative humidity and air temperature on concrete sewer corrosion.

    PubMed

    Jiang, Guangming; Keller, Jurg; Bond, Philip L

    2014-11-15

    Many studies of sewer corrosion are performed in accelerated conditions that are not representing the actual corrosion processes. This study investigated the effects of various factors over 3.5 years under controlled conditions simulating the sewer environment. Concrete coupons prepared from precorroded sewers were exposed, both in the gas phase and partially submerged in wastewater, in laboratory controlled corrosion chambers. Over the 45 month exposure period, three environmental factors of H2S concentration, relative humidity and air temperature were controlled at different levels in the corrosion chambers. A total of 36 exposure conditions were investigated to determine the long term effects of these factors by regular retrieval of concrete coupons for detailed analysis of surface pH, corrosion layer sulfate levels and concrete loss. Corrosion rates were also determined for different exposure periods. It was found that the corrosion rate of both gas-phase and partially-submerged coupons was positively correlated with the H2S concentration in the gas phase. Relative humidity played also a role for the corrosion activity of the gas-phase coupons. However, the partially-submerged coupons were not affected by humidity as the surfaces of these coupons were saturated due to capillary suction of sewage on the coupon surface. The effect of temperature on corrosion activity varied and possibly the acclimation of corrosion-inducing microbes to temperature mitigated effects of that factor. It was apparent that biological sulfide oxidation was not the limiting step of the overall corrosion process. These findings provide real insights into the long-term effects of these key environmental factors on the sewer corrosion processes.

  20. Determining the long-term effects of H₂S concentration, relative humidity and air temperature on concrete sewer corrosion.

    PubMed

    Jiang, Guangming; Keller, Jurg; Bond, Philip L

    2014-11-15

    Many studies of sewer corrosion are performed in accelerated conditions that are not representing the actual corrosion processes. This study investigated the effects of various factors over 3.5 years under controlled conditions simulating the sewer environment. Concrete coupons prepared from precorroded sewers were exposed, both in the gas phase and partially submerged in wastewater, in laboratory controlled corrosion chambers. Over the 45 month exposure period, three environmental factors of H2S concentration, relative humidity and air temperature were controlled at different levels in the corrosion chambers. A total of 36 exposure conditions were investigated to determine the long term effects of these factors by regular retrieval of concrete coupons for detailed analysis of surface pH, corrosion layer sulfate levels and concrete loss. Corrosion rates were also determined for different exposure periods. It was found that the corrosion rate of both gas-phase and partially-submerged coupons was positively correlated with the H2S concentration in the gas phase. Relative humidity played also a role for the corrosion activity of the gas-phase coupons. However, the partially-submerged coupons were not affected by humidity as the surfaces of these coupons were saturated due to capillary suction of sewage on the coupon surface. The effect of temperature on corrosion activity varied and possibly the acclimation of corrosion-inducing microbes to temperature mitigated effects of that factor. It was apparent that biological sulfide oxidation was not the limiting step of the overall corrosion process. These findings provide real insights into the long-term effects of these key environmental factors on the sewer corrosion processes. PMID:25108169

  1. Comparing three vegetation monoterpene emission models to measured gas concentrations with a model of meteorology, air chemistry and chemical transport

    NASA Astrophysics Data System (ADS)

    Smolander, S.; He, Q.; Mogensen, D.; Zhou, L.; Bäck, J.; Ruuskanen, T.; Noe, S.; Guenther, A.; Aaltonen, H.; Kulmala, M.; Boy, M.

    2014-10-01

    Biogenic volatile organic compounds (BVOCs) are essential in atmospheric chemistry because of their chemical reactions that produce and destroy tropospheric ozone, their effects on aerosol formation and growth, and their potential influence on global warming. As one of the important BVOC groups, monoterpenes have been a focus of scientific attention in atmospheric research. Detailed regional measurements and model estimates are needed to study emission potential and the monoterpene budget on a global scale. Since the use of empirical measurements for upscaling is limited by many physical and biological factors, such as genetic variation, temperature and light, water availability, seasonal changes, and environmental stresses, comprehensive inventories over larger areas are difficult to obtain. We applied the boundary-layer-chemistry-transport model SOSA (model to Simulate the concentrations of Organic vapours and Sulphuric Acid) to investigate Scots pine (Pinus sylvestris) monoterpene emissions in a boreal coniferous forest at the SMEAR (Station for Measuring forest Ecosystem-Atmosphere Relations) II site, southern Finland. SOSA was applied to simulate monoterpene emissions with three different emission modules: the semiempirical G95, MEGAN (Model of Emissions of Gases and Aerosols from Nature) 2.04 with improved descriptions of temperature and light responses and including also carbonyl emissions, and a process-based model SIM-BIM (Seasonal Isoprenoid synthase Model - Biochemical Isoprenoid biosynthesis Model). For the first time, the emission models included seasonal and diurnal variations in both quantity and chemical species of emitted monoterpenes, based on parameterizations obtained from field measurements. Results indicate that modelling and observations agreed reasonably well and that the model can be used for investigating regional air chemistry questions related to monoterpenes. The predominant modelled monoterpene concentrations, α-pinene and Δ3-carene

  2. Comparison of background levels of culturable fungal spore concentrations in indoor and outdoor air in southeastern Austria

    NASA Astrophysics Data System (ADS)

    Haas, D.; Habib, J.; Luxner, J.; Galler, H.; Zarfel, G.; Schlacher, R.; Friedl, H.; Reinthaler, F. F.

    2014-12-01

    Background concentrations of airborne fungi are indispensable criteria for an assessment of fungal concentrations indoors and in the ambient air. The goal of this study was to define the natural background values of culturable fungal spore concentrations as reference values for the assessment of moldy buildings. The concentrations of culturable fungi were determined outdoors as well as indoors in 185 dwellings without visible mold, obvious moisture problems or musty odor. Samples were collected using the MAS-100® microbiological air sampler. The study shows a characteristic seasonal influence on the background levels of Cladosporium, Penicillium and Aspergillus. Cladosporium sp. had a strong outdoor presence, whereas Aspergillus sp. and Penicillium sp. were typical indoor fungi. For the region of Styria, the median outdoor concentrations are between 100 and 940 cfu/m³ for culturable xerophilic fungi in the course of the year. Indoors, median background levels are between 180 and 420 cfu/m³ for xerophilic fungi. The I/O ratios of the airborne fungal spore concentrations were between 0.2 and 2.0. For the assessment of indoor and outdoor air samples the dominant genera Cladosporium, Penicillium and Aspergillus should receive special consideration.

  3. Applicability Limits of Beer's Law for Dispersion Media with a High Concentration of Particles.

    PubMed

    Dick, V P

    1998-07-20

    This study analyzes the values of volume concentrations of scatterers at which radiation extinction in dispersion media obeys Beer's law. The dependence of the maximum particle concentration at which Beer's law holds on the properties of the dispersion medium is investigated. It is shown that the maximum concentration is strongly dependent on the scatterers' parameters and varies over a wide range, from tenths to tens of percent.

  4. LOCATING NEARBY SOURCES OF AIR POLLUTION BY NONPARAMETRIC REGRESSION OF ATMOSPHERIC CONCENTRATIONS ON WIND DIRECTION. (R826238)

    EPA Science Inventory

    The relationship of the concentration of air pollutants to wind direction has been determined by nonparametric regression using a Gaussian kernel. The results are smooth curves with error bars that allow for the accurate determination of the wind direction where the concentrat...

  5. ORGANOCHLORINE PESTICIDE CONCENTRATIONS AND ENANTIOMER FRACTIONS FOR CHLORDANE IN INDOOR AIR FROM THE U.S. CORNBELT

    EPA Science Inventory

    Thirty-seven indoor air samples were collected and analyzed to determine if enantioselective degradation of past use organochlorine pesticides occurs indoors and to increase the available information on concentrations in homes. Samples were collected from homes in the U.S. cor...

  6. IN VITRO EFFECTS OF PARTICULATE MATTER ON AIRWAY EPITHELIAL CELLS ISOLATED FROM CONCENTRATED AIR PARTICLES-EXPOSED SPONTANEOUS HYPERTENSIVE RATS

    EPA Science Inventory

    In vitro effects of particulate matter on airway epithelial cells isolated from concentrated air particles-exposed spontaneous hypertensive rats

    Ines Pagan, Urmila Kodavanti, Paul Evansky, Daniel L Costa and Janice A Dye. U.S. Environmental Protection Agency, ORD, National...

  7. [Air negative charge ion concentration and its relationships with meteorological factors in different ecological functional zones of Hefei City].

    PubMed

    Wei, Chaoling; Wang, Jingtao; Jiang, Yuelin; Zhang, Qingguo

    2006-11-01

    Air negative charge ion concentration (ANCIC) has a close relationship with air quality. The observations on the ANCIC, sunlight intensity, air temperature, and air relative humidity in different ecological functional zones of Hefei City from 2003 to 2004 showed that the diurnal change pattern of ANCIC was of single peak in sightseeing and habitation zones, dual peak in industrial zone, and complicated in commercial zone. Different ecological functional zones had different appearance time of their daily ANCIC extremum. The diurnal fluctuation of ANCIC was in the order of commercial zone > industrial zone > habitation zone and sightseeing zone. The annual change pattern of ANCIC in these zones was similar, being the highest in summer and lowest in winter, and the mean annual ANCIC was 819, 340, 149 and 126 ions x cm(-3), respectively. The most important meteorological factor affecting the ANCIC in Hefei City was air relative humidity, followed by sunlight intensity and air temperature. There was an exponential relationship between ANCIC and air relative humidity.

  8. Effect of poverty on the relationship between personal exposures and ambient concentrations of air pollutants in Ho Chi Minh City

    NASA Astrophysics Data System (ADS)

    Mehta, Sumi; Sbihi, Hind; Dinh, Tuan Nguyen; Xuan, Dan Vu; Le Thi Thanh, Loan; Thanh, Canh Truong; Le Truong, Giang; Cohen, Aaron; Brauer, Michael

    2014-10-01

    Socioeconomic factors often affect the distribution of exposure to air pollution. The relationships between health, air pollution, and poverty potentially have important public health and policy implications, especially in areas of Asia where air pollution levels are high and income disparity is large. The objective of the study was to characterize the levels, determinants of exposure, and relationships between children personal exposures and ambient concentrations of multiple air pollutants amongst different socioeconomic segments of the population of Ho Chi Minh City, Vietnam. Using repeated (N = 9) measures personal exposure monitoring and determinants of exposure modeling, we compared daily average PM2.5, PM10, PM2.5 absorbance and NO2 concentrations measured at ambient monitoring sites to measures of personal exposures for (N = 64) caregivers of young children from high and low socioeconomic groups in two districts (urban and peri-urban), across two seasons. Personal exposures for both PM sizes were significantly higher among the poor compared to non-poor participants in each district. Absolute levels of personal exposures were under-represented by ambient monitors with median individual longitudinal correlations between personal exposures and ambient concentrations of 0.4 for NO2, 0.6 for PM2.5 and PM10 and 0.7 for absorbance. Exposures of the non-poor were more highly correlated with ambient concentrations for both PM size fractions and absorbance while those for NO2 were not significantly affected by socioeconomic position. Determinants of exposure modeling indicated the importance of ventilation quality, time spent in the kitchen, air conditioner use and season as important determinant of exposure that are not fully captured by the differences in socioeconomic position. Our results underscore the need to evaluate how socioeconomic position affects exposure to air pollution. Here, differential exposure to major sources of pollution, further influenced by

  9. The association of particulate air metal concentrations with heart rate variability.

    PubMed Central

    Magari, Shannon R; Schwartz, Joel; Williams, Paige L; Hauser, Russ; Smith, Thomas J; Christiani, David C

    2002-01-01

    Numerous studies show an association between particulate air pollution and adverse health effects. Particulate matter is a complex mixture of elemental carbon, ammonium, sulfates, nitrates, organic components, and metals. The mechanisms of action of particulate matter less than or equal to 2.5 micro m in mean aerodynamic diameter (PM(2.5)), as well as the constituents responsible for the observed cardiopulmonary health effects, have not been identified. In this study we focused on the association between the metallic component of PM(2.5) and cardiac autonomic function based on standard heart rate variability (HRV) measures in an epidemiologic study of boilermakers. Thirty-nine male boilermakers were monitored throughout a work shift. Each subject wore an ambulatory electrocardiogram (Holter) monitor and a personal monitor to measure PM(2.5). We used mixed-effects models to regress heart rate and SDNN index (standard deviation of the normal-to-normal) on PM(2.5) and six metals (vanadium, nickel, chromium, lead, copper, and manganese). There were statistically significant mean increases in the SDNN index of 11.30 msec and 3.98 msec for every 1 micro g/m(3) increase in the lead and vanadium concentrations, respectively, after adjusting for mean heart rate, age, and smoking status. Small changes in mean heart rate were seen with all exposure metrics. The results of this study suggest an association between exposure to airborne metals and significant alterations in cardiac autonomic function. These results extend our understanding of the adverse health effects of the metals component of ambient PM(2.5). PMID:12204821

  10. Air concentrations and wet deposition of major inorganic ions at five non-urban sites in China, 2001-2003

    NASA Astrophysics Data System (ADS)

    Aas, Wenche; Shao, Min; Jin, Lei; Larssen, Thorjørn; Zhao, Dawei; Xiang, Renjun; Zhang, Jinhong; Xiao, Jinsong; Duan, Lei

    Air and precipitation measurements at five sites were undertaken from 2001 to 2003 in four different provinces in China, as part of the acid rain monitoring program IMPACTS. The sites were located in Tie Shan Ping (TSP) in Chongqing, Cai Jia Tang (CJT) in Hunan, Lei Gong Shan (LGS) and Liu Chong Guan (LCG) in Guizhou and Li Xi He (LXH) in Guangdong. The site characteristics are quite varied with TSP and LCG located relatively near big cites while the three others are situated in more regionally representative areas. The distances to urban centres are reflected in the air pollution concentrations, with annual average concentrations of SO 2 ranging from 0.5 to above 40 μg S m -3. The main components in the airborne particles are (NH 4) 2SO 4 and CaSO 4. Reduced nitrogen has a considerably higher concentration level than oxidised nitrogen, reflecting the high ammonia emissions from agriculture. The gas/particle ratio for the nitrogen compounds is about 1:1 at all the three intensive measurement sites, while for sulphur it varies from 2.5 to 0.5 depending on the distance to the emission sources. As in air, the predominant ions in precipitation are sulphate, calcium and ammonium. The volume weighted annual concentration of sulphate ranges from about 70 μeq l -1 at the most rural site (LGS) to about 200 μeq l -1 at TSP and LCG. The calcium concentration ranges from 25 to 250 μeq l -1, while the total nitrogen concentration is between 30 and 150 μeq l -1; ammonium is generally twice as high as nitrate. China's acid rain research has traditionally been focused on urban sites, but these measurements show a significant influence of long range transported air pollutants to rural areas in China. The concentration levels are significantly higher than seen in most other parts of the world.

  11. Diagnostic Analysis of Ozone Concentrations Simulated by Two Regional-Scale Air Quality Models

    EPA Science Inventory

    Since the Community Multiscale Air Quality modeling system (CMAQ) and the Weather Research and Forecasting with Chemistry model (WRF/Chem) use different approaches to simulate the interaction of meteorology and chemistry, this study compares the CMAQ and WRF/Chem air quality simu...

  12. Analysis of mobile source air toxics (MSATs)–Near-Road VOC and carbonyl concentrations

    EPA Science Inventory

    Exposures to mobile source air toxics (MSATs) have been associated with numerous adverse health effects. While thousands of air toxic compounds are emitted from mobile sources, a subset of compounds are considered high priority due to their significant contribution to cancer and...

  13. Evaluation of background soil and air polychlorinated biphenyl (PCB) concentrations on a hill at the outskirts of a metropolitan city.

    PubMed

    Kuzu, S Levent; Saral, Arslan; Güneş, Gülten; Karadeniz, Aykut

    2016-07-01

    Air and soil sampling was conducted inside a forested area for 22 months. The sampling location is situated to the north of a metropolitan city. Average atmospheric gas and particle concentrations were found to be 180 and 28 pg m(-3) respectively, while that of soil phase was detected to be 3.2 ng g(-1) on dry matter, The congener pairs of PCB#4-10 had the highest contribution to each medium. TEQ concentration was 0.10 pg m(-3), 0.07 pg m(-3), 21.92 pg g(-1), for gas, particle and soil phases, respectively. PCB#126 and PCB#169 contributed to over 99% of the entire TEQ concentrations for each medium. Local sources were investigated by conditional probability function (CPF) and soil/air fugacity. Landfilling area and medical waste incinerator, located to the 8 km northeast, contributed to ambient concentrations, especially in terms of dioxin-like congeners. The industrial settlement (called Dilovasi being to the east southeast of 60 km distant) contributed from southeast direction. Further sources were identified by potential source contribution function (PSCF). Sources at close proximity had high contribution. Air mass transportation from Aliaga industrial region (being to the southwest of 300 km distant) moderately contributed to ambient concentrations. Low molecular weight congeners were released from soil body. 5-CBs and 6-CBs were close to equilibrium state between soil/air interfaces. PCB#171 was close to equilibrium and PCB#180 was likely to evaporate from soil, which constitute 7-CBs. PCB#199, representing 8-CBs deposited to soil. 9-CB (PCB#207) was in equilibrium between soil and air phases. PMID:27038903

  14. Experimental study of limit lean methane/air flame in a standard flammability tube using particle image velocimetry method

    SciTech Connect

    Shoshin, Yuriy; Gorecki, Grzegorz; Jarosinski, Jozef; Fodemski, Tadeusz

    2010-05-15

    Lean limit methane/air flame propagating upward in a standard 50 mm diameter and 1.8 m length tube was studied experimentally using particle image velocimetry method. Local stretch rate along the flame front was determined by measured gas velocity distributions. It was found that local stretch rate is maximum at the flame leading point, which is in agreement with earlier theoretical results. Similar to earlier observations, extinction of upward propagating limit flame was observed to start from the flame top. It is stated that the observed behavior of the extinction of the lean limit methane/air flame can not be explained in terms of the coupled effect of flame stretch and preferential diffusion. To qualitatively explain the observed extinction behavior, it is suggested that the positive strain-induced flame stretch increases local radiation heat losses from the flame front. An experimental methodology for PIV measurements in a round tube is described. (author)

  15. [Relationship of the ambient air concentrations of chemical substances to the spread of allergic diseases in children].

    PubMed

    Galeev, K A; Khakimova, R F

    2002-01-01

    The role of some ingredients that contaminate the ambient air in the occurrence and development of allergic diseases was studied. The closest relationships were found between the concentrations of hydrogen sulfide and the prevalence of eczema (rxy +/- m = 0.48 +/- 0.15). There was a direct correlation between the concentrations of each ingredient and the incidence of neurodermitis among children. The correlation between the summarized concentrations of ingredients and the incidence of bronchial asthma among children was rxy +/- m = 0.71 +/- 0.19. The findings serves as the basis for elaborating measures to reduce ecological tension and the incidence of allergic diseases in children. PMID:12380496

  16. Limitations of the scientific basis for the management of air quality in urban New Zealand.

    PubMed

    Hoare, John L

    2011-03-04

    As enumerated by Ministry for the Environment, planned reductions in levels of air pollution in New Zealand sufficient to allow compliance with the National Environmental Standards for Air Quality will save, in a cost-effective manner, numerous lives per year. However, as indicated by careful study of the literature and of the methods employed to perform the relevant calculations, such claims are flawed. Instead of a precise number of deaths avoided, small changes in regional life expectancy are a more likely tangible consequence of compliance and, as such, are better suited to assisting calculation of the associated benefits and costs. Some basic data relevant to communities and regions potentially susceptible to the effects of 'poor quality' or inclement air are provided. These support the view that urban air pollution as officially measured and normally encountered in New Zealand nowadays probably has comparatively small substantive mortality consequences.

  17. Assessment of an aerosol treatment to improve air quality in a swine concentrated animal feeding operation (CAFO).

    PubMed

    Rule, Ana M; Chapin, Amy R; McCarthy, Sheila A; Gibson, Kristen E; Schwab, Kellogg J; Buckley, Timothy J

    2005-12-15

    Poor air quality within swine concentrated animal feeding operations (CAFOs) poses a threat to workers, the surrounding community, and farm production. Accordingly, the current study was conducted to evaluate a technology for reducing air pollution including particulate matter (PM), viable bacteria, and ammonia within such a facility. The technology consists of an acid-oil-alcohol aerosol applied daily. Its effectiveness was evaluated by comparing air quality from before to after treatment and between treated and untreated sides of a barn separated by an impervious partition. On the untreated side, air quality was typical for a swine CAFO, with mean PM2.5 of 0.28 mg/m3 and PM(TOT) of 1.5 mg/m3. The treatment yielded a reduction in PM concentration of 75-90% from before to after treatment. Effectiveness increased with time, application, and particle size (40% reduction for 1 microm and 90% for >10 microm). Airborne bacteria levels (total bacteria, Enterobacteriaceae, and gram-positive cocci) decreased one logarithmic unit after treatment. In contrast, treatment had no effect on ammonia concentrations. These findings demonstrate the effectiveness of an intervention in yielding exposure and emission reductions. PMID:16475347

  18. Variations in vanadium, nickel and lanthanoid element concentrations in urban air.

    PubMed

    Moreno, Teresa; Querol, Xavier; Alastuey, Andrés; de la Rosa, Jesús; Sánchez de la Campa, Ana María; Minguillón, Maricruz; Pandolfi, Marco; González-Castanedo, Yolanda; Monfort, Eliseo; Gibbons, Wes

    2010-09-15

    The emission of trace metal pollutants by industry and transport takes place on a scale large enough to alter atmospheric chemistry and results in measurable differences between the urban background of inhalable particulate matter (PM) in different towns. This is particularly well demonstrated by the technogenic release into the atmosphere of V, Ni, and lanthanoid elements. We compare PM concentrations of these metals in large datasets from five industrial towns in Spain variously influenced by emissions from refinery, power station, shipping, stainless steel, ceramic tiles and brick-making. Increased La/Ce values in urban background inhalable PM, due to La-contamination from refineries and their residual products (fuel oils and petcoke), contrast with Ce-rich emissions from the ceramic related industry, and clearly demonstrate the value of this ratio as a sensitive and reliable tracer for many point source emissions. Similarly, anomalously high V/Ni values (>4) can detect the influence of nearby high-V petcoke and fuel oil combustion, although the use of this ratio in urban background PM is limited by overlapping values in natural and anthropogenic materials. Geochemical characterisation of urban background PM is a valuable compliment to the physical monitoring of aerosols widely employed in urban areas, especially given the relevance of trace metal inhalation to urban health issues. PMID:20599248

  19. Relationships between ozone photolysis rates and peroxy radical concentrations in clean marine air over the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Penkett, S. A.; Monks, P. S.; Carpenter, L. J.; Clemitshaw, K. C.; Ayers, G. P.; Gillett, R. W.; Galbally, I. E.; Meyer, C. P.

    1997-06-01

    Measurements of the sum of inorganic and organic peroxy radicals (RO2) and photolysis rate coefficients J(NO2) and J(O1D) have been made at Cape Grim, Tasmania in the course of a comprehensive experiment which studied photochemistry in the unpolluted marine boundary layer. The SOAPEX (Southern Ocean Atmospheric Photochemistry Experiment) campaign included measurements of ozone, peroxides, nitrogen oxides, water vapor, and many other parameters. This first full length paper concerned with the experiment focuses on the types of relationships observed between peroxy radicals and J(NO2), J(O1D) and √[J(O1D)] in different air masses in which ozone is either produced or destroyed by photochemistry. It was found that in baseline air with ozone loss, RO2 was proportional to √[J(O1D)], whereas in more polluted air RO2 was proportional to J(O1D). Simple algorithms were derived to explain these relationships and also to calculate the concentrations of OH radicals in baseline air from the instantaneous RO2 concentrations. The signal to noise ratio of the peroxy radical measurements was up to 10 for 1-min values and much higher than in other previous deployments of the instrument in the northern hemisphere, leading to the confident determination of the relationships between RO2 and J(O1D) in different conditions. The absolute concentration Of RO2 determined in these experiments is in some doubt, but this does not affect our conclusions concerned either with the behavior of peroxy radicals with changing light levels or with the concentrations of OH calculated from RO2. The results provide confidence that the level of understanding of the photochemistry of ozone leading to the production of peroxide via recombination of peroxy radicals in clean air environments is well advanced.

  20. Assessing concentrations and health impacts of air quality management strategies: Framework for Rapid Emissions Scenario and Health impact ESTimation (FRESH-EST).

    PubMed

    Milando, Chad W; Martenies, Sheena E; Batterman, Stuart A

    2016-09-01

    In air quality management, reducing emissions from pollutant sources often forms the primary response to attaining air quality standards and guidelines. Despite the broad success of air quality management in the US, challenges remain. As examples: allocating emissions reductions among multiple sources is complex and can require many rounds of negotiation; health impacts associated with emissions, the ultimate driver for the standards, are not explicitly assessed; and long dispersion model run-times, which result from the increasing size and complexity of model inputs, limit the number of scenarios that can be evaluated, thus increasing the likelihood of missing an optimal strategy. A new modeling framework, called the "Framework for Rapid Emissions Scenario and Health impact ESTimation" (FRESH-EST), is presented to respond to these challenges. FRESH-EST estimates concentrations and health impacts of alternative emissions scenarios at the urban scale, providing efficient computations from emissions to health impacts at the Census block or other desired spatial scale. In addition, FRESH-EST can optimize emission reductions to meet specified environmental and health constraints, and a convenient user interface and graphical displays are provided to facilitate scenario evaluation. The new framework is demonstrated in an SO2 non-attainment area in southeast Michigan with two optimization strategies: the first minimizes emission reductions needed to achieve a target concentration; the second minimizes concentrations while holding constant the cumulative emissions across local sources (e.g., an emissions floor). The optimized strategies match outcomes in the proposed SO2 State Implementation Plan without the proposed stack parameter modifications or shutdowns. In addition, the lower health impacts estimated for these strategies suggest that FRESH-EST could be used to identify potentially more desirable pollution control alternatives in air quality management planning.

  1. Assessing concentrations and health impacts of air quality management strategies: Framework for Rapid Emissions Scenario and Health impact ESTimation (FRESH-EST).

    PubMed

    Milando, Chad W; Martenies, Sheena E; Batterman, Stuart A

    2016-09-01

    In air quality management, reducing emissions from pollutant sources often forms the primary response to attaining air quality standards and guidelines. Despite the broad success of air quality management in the US, challenges remain. As examples: allocating emissions reductions among multiple sources is complex and can require many rounds of negotiation; health impacts associated with emissions, the ultimate driver for the standards, are not explicitly assessed; and long dispersion model run-times, which result from the increasing size and complexity of model inputs, limit the number of scenarios that can be evaluated, thus increasing the likelihood of missing an optimal strategy. A new modeling framework, called the "Framework for Rapid Emissions Scenario and Health impact ESTimation" (FRESH-EST), is presented to respond to these challenges. FRESH-EST estimates concentrations and health impacts of alternative emissions scenarios at the urban scale, providing efficient computations from emissions to health impacts at the Census block or other desired spatial scale. In addition, FRESH-EST can optimize emission reductions to meet specified environmental and health constraints, and a convenient user interface and graphical displays are provided to facilitate scenario evaluation. The new framework is demonstrated in an SO2 non-attainment area in southeast Michigan with two optimization strategies: the first minimizes emission reductions needed to achieve a target concentration; the second minimizes concentrations while holding constant the cumulative emissions across local sources (e.g., an emissions floor). The optimized strategies match outcomes in the proposed SO2 State Implementation Plan without the proposed stack parameter modifications or shutdowns. In addition, the lower health impacts estimated for these strategies suggest that FRESH-EST could be used to identify potentially more desirable pollution control alternatives in air quality management planning

  2. Cardiovascular Effects in Adults with Metabolic Syndrome Exposed to Concentrated Ultrafine Air Pollution Particles

    EPA Science Inventory

    RATIONALE: Epidemiologic studies report associations between ambient air pollution particulate matter (PM) and various indices of cardiopulmonary morbidity and mortality. A leading hypothesis contends that smaller ultrafine (UF) particles induce a greater physiologic response bec...

  3. Short-term effects of air temperature on plasma metabolite concentrations in patients undergoing cardiac cattheterization.

    EPA Science Inventory

    BACKGROUND: Epidemiological studies have shown associations between air temperature and cardiovascular health outcomes. Metabolic dysregulation might also play a role in the development of cardiovascular disease.OBJECTIVES: To investigate short-term temperature effects on metabol...

  4. ASSESSING THE COMPARABILITY OF AMMONIUM, NITRATE AND SULFATE CONCENTRATIONS MEASURED BY THREE AIR QUALITY MONITORING NETWORKS

    EPA Science Inventory

    Airborne fine particulate matter across the United States is monitored by different networks, the three prevalent ones presently being the Clean Air Status and Trend Network (CASTNet), the Interagency Monitoring of PROtected Visual Environment Network (IMPROVE) and the Speciati...

  5. Air pollution and associated human mortality: The role of air pollutant emissions, climate change and methane concentration increases during the industrial period

    NASA Astrophysics Data System (ADS)

    Fang, Y.; Naik, V.; Horowitz, L. W.; Mauzerall, D. L.

    2012-12-01

    Increases in surface ozone (O3) and fine particulate matter (≤ 2.5μm aerodynamic diameter, PM2.5) are associated with excess premature human mortalities. Here we estimate changes in surface O3 and PM2.5 since preindustrial (1860) times and the global present-day (2000) premature human mortalities associated with these changes. We go beyond previous work to analyze and differentiate the contribution of three factors: changes in emissions of short-lived air pollutants, climate change, and increased methane (CH4) concentrations, to air pollution levels and the associated premature mortalities. We use a coupled chemistry-climate model in conjunction with global population distributions in 2000 to estimate exposure attributable to concentration changes since 1860 from each factor. Attributable mortalities are estimated using health impact functions of long-term relative risk estimates for O3 and PM2.5 from the epidemiology literature. We find global mean surface PM2.5 and health-relevant O3 (defined as the maximum 6-month mean of 1-hour daily maximum O3 in a year) have increased by 8±0.16 μg/m3 and 30±0.16 ppbv, respectively, over this industrial period as a result of combined changes in emissions of air pollutants (EMIS), climate (CLIM) and CH4 concentrations (TCH4). EMIS, CLIM and TCH4 cause global average PM2.5 (O3) to change by +7.5±0.19 μg/m3 (+25±0.30 ppbv), +0.4±0.17 μg/m3 (+0.5±0.28 ppbv), and -0.02±0.01 μg/m3 (+4.3±0.33 ppbv), respectively. Total changes in PM2.5 are associated with 1.5 (95% confidence interval, CI, 1.0-2.5) million all-cause mortalities annually and in O3 are associated with 375 (95% CI, 129-592) thousand respiratory mortalities annually. Most air pollution mortality is driven by changes in emissions of short-lived air pollutants and their precursors (95% and 85% of mortalities from PM2.5 and O3 respectively). However, changing climate and increasing CH4 concentrations also increased premature mortality associated with air

  6. Air pollution and associated human mortality: the role of air pollutant emissions, climate change and methane concentration increases during the industrial period

    NASA Astrophysics Data System (ADS)

    Fang, Y.; Naik, V.; Horowitz, L. W.; Mauzerall, D. L.

    2012-09-01

    Increases in surface ozone (O3) and fine particulate matter (≤2.5 μm} aerodynamic diameter, PM2.5) are associated with excess premature human mortalities. Here we estimate changes in surface O3 and PM2.5 since preindustrial (1860) times and the global present-day (2000) premature human mortalities associated with these changes. We go beyond previous work to analyze and differentiate the contribution of three factors: changes in emissions of short-lived air pollutants, climate change, and increased methane (CH4) concentrations, to air pollution levels and the associated premature mortalities. We use a coupled chemistry-climate model in conjunction with global population distributions in 2000 to estimate exposure attributable to concentration changes since 1860 from each factor. Attributable mortalities are estimated using health impact functions of long-term relative risk estimates for O3 and PM2.5 from the epidemiology literature. We find global mean surface PM2.5 and health-relevant O3 (defined as the maximum 6-month mean of 1-h daily maximum O3 in a year) have increased by 8 ± 0.16 μg m-3 and 30 ± 0.16 ppbv, respectively, over this industrial period as a result of combined changes in emissions of air pollutants (EMIS), climate (CLIM) and CH4 concentrations (TCH4). EMIS, CLIM and TCH4 cause global average PM2.5(O3) to change by +7.5 ± 0.19 μg m-3 (+25 ± 0.30 ppbv), +0.4 ± 0.17 μg m-3 (+0.5 ± 0.28 ppbv), and -0.02 ± 0.01 μg m-3 (+4.3 ± 0.33 ppbv), respectively. Total changes in PM2.5 are associated with 1.5 (95% confidence interval, CI, 1.0-2.5) million all-cause mortalities annually and in O3 are associated with 375 (95% CI, 129-592) thousand respiratory mortalities annually. Most air pollution mortality is driven by changes in emissions of short-lived air pollutants and their precursors (95% and 85% of mortalities from PM2.5 and O3, respectively). However, changing climate and increasing CH4 concentrations also increased premature mortality

  7. Radon ((222)Rn) concentration in indoor air near the coal mining area of Nui Beo, North of Vietnam.

    PubMed

    Nhan, Dang Duc; Fernando, Carvalho P; Thu Ha, Nguyen Thi; Long, Nguyen Quang; Thuan, Dao Dinh; Fonseca, Heloisa

    2012-08-01

    Concentrations of radioactive radon gas ((222)Rn) were measured using passive monitors based on LR115 solid state track detectors during June-July 2010 in indoor air of dwellings in the Nui Beo coal mining area, mostly in Cam Pha and Ha Long coastal towns, Quang Ninh province, in the North of Vietnam. Global results of (222)Rn concentrations indoors varied from ≤6 to 145 Bq m(-3) averaging 46 ± 26 Bq m(-3) (n = 37), with a median value of 47 Bq m(-3). This was similar to outdoor (222)Rn concentrations in the region, averaging 43 ± 19 Bq m(-3) (n = 10), with a median value of 44 Bq m(-3). Indoor (222)Rn concentrations in the coastal town dwellings only were in average lower although not significantly different from indoor (222)Rn concentrations measured at the coal storage field near the harbor, 67 ± 4 Bq m(-3) (n = 3). Furthermore, there was no significant difference in the average (222)Rn concentration in indoor air measured in the coastal towns region and those at the touristic Tuan Chau Island located about 45 km south of the coal mine, in the Ha Long Bay. The indoor (222)Rn concentration in a floating house at the Bai Tu Long Bay, and assumed as the best estimate of the baseline (222)Rn in surface air, was 27 ± 3 Bq m(-3) (n = 3). Indoor average concentration of (222)Rn in dwellings at the Ha Noi city, inland and outside the coal mining area, was determined at 30 Bq m(-3). These results suggest that (222)Rn exhalation from the ground at the Nui Beo coal mining area may have contributed to generally increase (222)Rn concentration in the surface air of that region up to 1.7 times above the baseline value measured at the Bai Tu Long Bay and Ha Noi. The average indoor concentration of (222)Rn in Cam Pha-Ha Long area is about one-third of the value of the so-called Action Level set up by the US EPA of 148 Bq m(-3). Results suggest that there is no significant public health risk from (222)Rn exposure in the study region.

  8. Source evaluation report phase 2 investigation: Limited field investigation. Final report: United States Air Force Environmental Restoration Program, Eielson Air Force Base, Alaska

    SciTech Connect

    Not Available

    1994-10-01

    This report describes the limited field investigation work done to address issues and answer unresolved questions regarding a collection of potential contaminant sources at Eielson Air Force Base (AFB), near Fairbanks, Alaska. These sources were listed in the Eielson AFB Federal Facility Agreement supporting the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) cleanup of the base. The limited field investigation began in 1993 to resolve all remaining technical issues and provide the data and analysis required to evaluate the environmental hazard associated with these sites. The objective of the limited field investigation was to allow the remedial project managers to sort each site into one of three categories: requiring remedial investigation/feasibility study, requiring interim removal action, or requiring no further remedial action.

  9. Effects of diesel exhaust aftertreatment devices on concentrations and size distribution of aerosols in underground mine air.

    PubMed

    Bugarski, Aleksandar D; Schnakenberg, George H; Hummer, Ion A; Cauda, Emanuele; Janisko, Samuel I; Patts, Larry D

    2009-09-01

    Three types of uncatalyzed diesel particulate filter (DPF) systems, three types of high-temperature disposable filter elements (DFEs), and one diesel oxidation catalytic converter (DOC) were evaluated in underground mine conditions for their effects on the concentrations and size distributions of diesel aerosols. Those effects were compared with the effects of a standard muffler. The experimental work was conducted directly in an underground environment using a unique diesel laboratory developed in an underground experimental mine. The DPF systems reduced total mass of aerosols in the mine air approximately 10-fold for light-load and 20-fold or more for high-load test conditions. The DFEs offered similar reductions in aerosol mass concentrations. The efficiency of the new DFEs significantly increased with accumulation of operating time and buildup of diesel particulate matter in the porous structure of the filter elements. A single laundering process did not exhibit substantial effects on performance of the filter element The effectiveness of DPFs and DFEs in removing aerosols by number was strongly influenced by engine operating mode. The concentrations of nucleation mode aerosols in the mine air were found to be substantially higher for both DPFs and DFEs when the engine was operated at high-load modes than at low-load modes. The effects of the DOC on mass and number concentrations of aerosols in mine air were relatively minor when compared to those of the DPF and DFE systems.

  10. The effect of incomplete fuel-air mixing on the lean blowout limit, lean stability limit and NO(x) emissions in lean premixed gas turbine combustors

    NASA Technical Reports Server (NTRS)

    Shih, W.-P.; Lee, J. G.; Santavicca, D. A.

    1994-01-01

    Gas turbine engines for both land-based and aircraft propulsion applications are facing regulations on NOx emissions which cannot be met with current combustor technology. A number of alternative combustor strategies are being investigated which have the potential capability of achieving ultra-low NOx emissions, including lean premixed combustors, direct injection combustors, rich burn-quick quench-lean burn combustors and catalytic combustors. The research reported in this paper addresses the effect of incomplete fuel-air mixing on the lean limit performance and the NOx emissions characteristics of lean premixed combustors.

  11. The effect of time of exposure to elevated temperatures on the flammability limits of some common gaseous fuels in air

    SciTech Connect

    Wierzba, I.; Ale, B.B.

    1999-01-01

    The flammability limits of methane, ethylene, propane, and hydrogen were experimentally determined at elevated initial mixture temperatures up to 350 C at atmospheric pressure for upward flame propagation in a steel test tube apparatus. The existence of preignition reactions at these levels of temperatures that may influence the value of the flammability limits was also investigated. The fuel-air mixtures were exposed to elevated temperatures over different periods of time before spark ignition (up to 2 h). It was shown that the flammability limits for methane widened approximately linearly with an increase in the initial mixture temperature over the entire range of temperatures tested and were not affected by the length of the exposure time to these temperatures before spark ignition. However, different behavior was observed for the flammability limits of the other tested fuels--ethylene, propane, and hydrogen. At higher temperatures the flammability limits narrowed and were very significantly affected by the exposure time. The longer was the exposure time of fuel-air mixtures to the elevated temperatures, the narrower were their flammability limits.

  12. 40 CFR 227.27 - Limiting permissible con-cen-tra-tion (LPC).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...; or, when there are no applicable marine water quality criteria, (2) That concentration of waste or... procedures. (3) When there is reasonable scientific evidence on a specific waste material to justify the use... not cause unreasonable acute or chronic toxicity or other sublethal adverse effects based on...

  13. Evaluation of Land Use Regression Models Used to Predict Air Quality Concentrations in an Urban Area

    EPA Science Inventory

    Cohort studies designed to estimate human health effects of exposures to urban pollutants require accurate determination of ambient concentrations in order to minimize exposure misclassification errors. However, it is often difficult to collect concentration information at each s...

  14. Air pollution impacts of speed limitation measures in large cities: The need for improving traffic data in a metropolitan area

    NASA Astrophysics Data System (ADS)

    Baldasano, José M.; Gonçalves, María; Soret, Albert; Jiménez-Guerrero, Pedro

    2010-08-01

    Assessing the effects of air quality management strategies in urban areas is a major concern worldwide because of the large impacts on health caused by the exposure to air pollution. In this sense, this work analyses the changes in urban air quality due to the introduction of a maximum speed limit to 80 km h -1 on motorways in a large city by using a novel methodology combining traffic assimilation data and modelling systems implemented in a supercomputing facility. Albeit the methodology has been non-specifically developed and can be extrapolated to any large city or megacity, the case study of Barcelona is presented here. Hourly simulations take into account the entire year 2008 (when the 80 km h -1 limit has been introduced) vs. the traffic conditions for the year 2007. The data has been assimilated in an emission model, which considers hourly variable speeds and hourly traffic intensity in the affected area, taken from long-term measurement campaigns for the aforementioned years; it also permits to take into account the traffic congestion effect. Overall, the emissions are reduced up to 4%; however the local effects of this reduction achieve an important impact for the adjacent area to the roadways, reaching 11%. In this sense, the speed limitation effects assessed represent enhancements in air quality levels (5-7%) of primary pollutants over the area, directly improving the welfare of 1.35 million inhabitants (over 41% of the population of the Metropolitan Area) and affecting 3.29 million dwellers who are potentially benefited from this strategy for air quality management (reducing 0.6% the mortality rates in the area).

  15. Rainwater monocarboxylic and dicarboxylic acid concentrations in southeastern North Carolina, USA, as a function of air-mass back-trajectory

    NASA Astrophysics Data System (ADS)

    Brooks Avery, G.; Kieber, Robert J.; Witt, Melanie; Willey, Joan D.

    Eight organic acids were measured in 111 rain events occurring between September 1996 and May 1998 in Wilmington, North Carolina. Formic and acetic acids were the most abundant comprising approximately 75% of the total molar quantity of organic acids. The annual volume-weighted concentrations of organic acids in order of decreasing abundance in rainwater was formic (9.9 μM), acetic (7.3 μM), oxalic (1.8 μM), lactic (1.3 μM), succinic (1.0 μM), malonic (0.7 μM), pyruvic (0.3 μM), and maleic (0.1 μM), with methanesulfonic and glyoxylic acids usually below their detection limit. Growing season back-trajectory data provided strong evidence that terrestrial organic acid sources dominated over marine sources. Air mass back-trajectory analysis indicated that during the growing season air mass origin had a consistent impact on concentrations of rainwater organic acids. Rain with continental back-trajectories coming from the west had the highest concentrations of organic acids while two predominately marine back-trajectories had the lowest concentrations. Concentrations of organic acids in non-growing season rain did not display a consistent pattern indicating variability in sources. Seasonality of individual organic acids for specific back-trajectories was most pronounced in terrestrial back-trajectories and least in the marine back-trajectories indicating that seasonality in rainwater organic acid concentrations is driven by variations in terrestrial sources. Formic to acetic acid ratios (F:A), previously an indicator of terrestrial versus marine sources of these organic acids, were similar for all back-trajectories reflecting anthropogenic impacts on F:A locally and regionally. The ratios of malonic to succinic acids (M:S), also an indicator of sources for these acids, indicated direct anthropogenic sources for terrestrial back-trajectories and secondary processes for marine back-trajectories.

  16. AIRNET Data from Los Alamos National Laboratory: Air Concentration Data by Site and Isotope/Element

    DOE Data Explorer

    Ambient monitoring is the systematic, long-term assessment of pollutant levels by measuring the quantity and types of certain pollutants in the surrounding, outdoor air. The purpose of AIRNET, LANL's ambient air monitoring network, is to monitor locations where people live or work. The community of Los Alamos is downwind from LANL, so there are many monitoring stations in and around the town. AIRNET stations monitor 24 hours a day, 365 days of the year. Particulates are collected on a filter and analyzed every two weeks for identification of analytes and assessment of the potential impact on the public. Emissions measurement is the process of monitoring materials vented from buildings. Air samples are taken from building exhaust units, called stacks, and are then analyzed for particulate matter, tritium, and radioactive gases and vapors. A computer model uses the emission data to determine the dispersion. Stack monitoring is also used to measure emissions that cannot be measured by AIRNET stations.

  17. A method to derive the relationship between the annual and short-term air quality limits--analysis using the WHO Air Quality Guidelines for health protection.

    PubMed

    Lai, Hak-Kan; Hedley, Anthony J; Thach, Thuan-Quoc; Wong, Chit-Ming

    2013-09-01

    The World Health Organization (WHO) Air Quality Guidelines (AQG) were launched in 2006, but gaps remain in evidence on health impacts and relationships between short-term and annual AQG needed for health protection. We tested whether relationships between WHO short-term and annual AQG for particulates (PM10 and PM2.5) and nitrogen dioxide (NO2) are concordant worldwide and derived the annual limits for sulfur dioxide (SO2) and ozone (O3) based on the short-term AQG. We obtained air pollutant data over seven years (2004-2010) in seven cities from Asia-Pacific, North America and Europe. Based on probability distribution concept using maximum as the short-term limit and arithmetic mean as the annual limit, we developed a new method to derive limit value one from another in each paired limits for each pollutant with capability to account for allowable exceedances. We averaged the limit derived each year for each city, then used meta-analysis to pool the limit values in all cities. Pooled mean short-term limit for NO2 (140.5μg/m(3) [130.6-150.4]) was significantly lower than the WHO AQG of 200μg/m(3) while for PM10 (46.4μg/m(3) [95CI:42.1-50.7]) and PM2.5 (28.6μg/m(3) [24.5-32.6]) were not significantly different from the WHO AQG of 50 and 25μg/m(3) respectively. Pooled mean annual limits for SO2 and O3 were 4.6μg/m(3) [3.7-5.5] and 27.0μg/m(3) [21.7-32.2] respectively. Results were robust in various sensitivity analyses. The distribution relationships between the current WHO short-term and annual AQG are supported by empirical data from seven cities for PM10 and PM2.5, but not for NO2. The short-term AQG for NO2 should be lowered for concordance with the selected annual AQG for health protection. PMID:23792417

  18. 76 FR 10220 - Airworthiness Directives; Viking Air Limited (Type Certificate No. A-815 Formerly Held by...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-24

    ... ] December 7, 2010 (75 FR 75932). That NPRM proposed to require repetitively inspecting the elevator control... Order 12866, (2) Is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034...-020-AD; Amendment 39-16611; AD 2011-05-02] RIN 2120-AA64 Airworthiness Directives; Viking Air...

  19. 75 FR 75932 - Airworthiness Directives; Viking Air Limited (Type Certificate No. A-815 Formerly Held by...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-07

    ..., contact Viking Air Ltd., 9574 Hampden Road, Sidney, BC Canada V8L 5V5; telephone: (800) 663-8444; Internet... edge of the servo tab). Collecting this information will help us better understand the service history... ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979), (3)...

  20. Comparison of two different passive air samplers (PUF-PAS versus SIP-PAS) to determine time-integrated average air concentration of volatile hydrophobic organic pollutants

    NASA Astrophysics Data System (ADS)

    Kim, Seung-Kyu; Park, Jong-Eun

    2014-06-01

    Despite remarkable achievements with r some chemicals, a field-measurement technique has not been advanced for volatile hydrophobic organic chemicals (HOCs) that are the subjects of international concern. This study assesses the applicability of passive air sampling (PAS) by comparing PUF-PAS and its modified SIP-PAS which was made by impregnating XAD-4 powder into PUF, overviewing the principles of PAS, screening sensitive parameters, and determining the uncertainty range of PAS-derived concentration. The PAS air sampling rate determined in this study, corrected by a co-deployed low-volume active air sampler (LAS) for neutral PFCs as model chemicals, was ˜1.2 m3 day-1. Our assessment shows that the improved sorption capacity in a SIP lengthens PAS deployment duration by expanding the linear uptake range and then enlarges the effective air sampling volume and detection frequency of chemicals at trace level. Consequently, volatile chemicals can be collected during sufficiently long times without reaching equilibrium when using SIP, while this is not possible for PUF. The most sensitive parameter to influence PAS-derived CA was an air-side mass transfer coefficient (kA), implying the necessity of spiking depuration chemicals (DCs) because this parameter is strongly related with meteorological conditions. Uncertainty in partition coefficients (KPSM-A or KOA) influences PAS-derived CA to a greater extent with regard to lower KPSM-A chemicals. Also, the PAS-derived CA has an uncertainty range of a half level to a 3-fold higher level of the calculated one. This work is expected to establish solid grounds for the improvement of field measurement technique of HOCs.

  1. Limitations to the Measurement of Oxygen Concentrations by HRTEM Imposed by Surface Roughness

    SciTech Connect

    Lupini, Andrew R; Chisholm, Matthew F; van Benthem, Klaus; Allen, L. J.; Oxley, Mark P; Findlay, Scott D.; Varela del Arco, Maria; Pennycook, Stephen J

    2005-01-01

    In an article published in Microscopy and Microanalysis recently (Jia et al., 2004), it was claimed that aberration-corrected high resolution transmission electron microscopy (HRTEM) allows the quantitative measurement of oxygen concentrations in ceramic materials with atomic resolution. Similar claims have recently appeared elsewhere, based on images obtained through aberration correction (Jia et al., 2003; Jia & Urban, 2004) or very high voltages (Zhang et al., 2003). Seeing oxygen columns is a significant achievement of great importance (Spence, 2003) that will doubtlessly allow some exciting new science; however, other models could provide a better explanation for some of the experimental data than variations in the oxygen concentration. Quantification of the oxygen concentrations was attempted by comparing experimental images with simulations in which the fractional occupancy in individual oxygen columns was reduced. The results were interpreted as representing nonstoichiometry within the bulk and at grain boundaries. This is plausible because previous studies have shown that grain boundaries can be nonstoichiometric (Kim et al., 2001), and it is indeed possible that oxygen vacancies are present at boundaries or in the bulk. However, is this the only possible interpretation? We show that for the thicknesses considered a better match to the images is obtained using a simple model of surface damage in which atoms are removed from the surface, which would usually be interpreted as surface damage or local thickness variation (from ion milling, for example).

  2. Amelioration of the reactive nitrogen flux calculation by a day/night separation in weekly mean air concentration measurements

    NASA Astrophysics Data System (ADS)

    Hayashi, Kentaro; Matsuda, Kazuhide; Ono, Keisuke; Tokida, Takeshi; Hasegawa, Toshihiro

    2013-11-01

    The low time resolution of air concentration data of atmospheric deposition in regional monitoring networks makes it difficult to estimate fluxes between the land and the atmosphere. The present study was an evaluation of the effects of day/night separation for a low time resolution of air concentration measurements (i.e., weekly mean) for the estimation of reactive nitrogen fluxes. The target chemical species included reactive nitrogen primarily ammonia (NH3) and nitric acid gas (HNO3) and secondarily nitrous acid gas, particulate ammonium, and particulate nitrate in addition to sulfur dioxide (SO2) as a reference. Monitoring was conducted for one year at a single-crop rice paddy field in central Japan. The study period was divided into the cropping and fallow seasons, which were characterized by rice plants or a drained bare soil surface, respectively. The filter-pack method was applied to measure the weekly mean air concentrations with day/night separation for the target species at two heights (6 and 2 m above the ground surface). Both an inferential and a gradient method were applied to calculate the deposition and exchange fluxes, respectively. The day/night separation in a weekly sampling protocol, on average, reduced the underestimation of HNO3 fluxes for the inferential method by 15.2% ± 6.8% and 8.2% ± 6.1% in the cropping and fallow seasons, respectively, and reduced the overestimation of NH3 fluxes for the gradient method by 121% ± 128% in the cropping season. The fluxes calculated using the inferential method agreed relatively well with those calculated using the gradient method for HNO3 and SO2. The use of single-height measurements for air concentrations with day/night separation and flux calculations using the inferential method are recommended as an appropriate way to enhance the quality in calculated fluxes while simultaneously suppress the increase in labor cost.

  3. Increasing the Upper Temperature Oxidation Limit of Alumina Forming Austenitic Stainless Steels in Air with Water Vapor

    SciTech Connect

    Brady, Michael P; Unocic, Kinga A; Lance, Michael J; Santella, Michael L; Yamamoto, Yukinori; Walker, Larry R

    2011-01-01

    A family of alumina-forming austenitic (AFA) stainless steels is under development for use in aggressive oxidizing conditions from {approx}600-900 C. These alloys exhibit promising mechanical properties but oxidation resistance in air with water vapor environments is currently limited to {approx}800 C due to a transition from external protective alumina scale formation to internal oxidation of aluminum with increasing temperature. The oxidation behavior of a series of AFA alloys was systematically studied as a function of Cr, Si, Al, C, and B additions in an effort to provide a basis to increase the upper-temperature oxidation limit. Oxidation exposures were conducted in air with 10% water vapor environments from 800-1000 C, with post oxidation characterization of the 900 C exposed samples by electron probe microanalysis (EPMA), scanning and transmission electron microscopy, and photo-stimulated luminescence spectroscopy (PSLS). Increased levels of Al, C, and B additions were found to increase the upper-temperature oxidation limit in air with water vapor to between 950 and 1000 C. These findings are discussed in terms of alloy microstructure and possible gettering of hydrogen from water vapor at second phase carbide and boride precipitates.

  4. Can changing the timing of outdoor air intake reduce indoor concentrations of traffic-related pollutants in schools?

    PubMed

    MacNeill, M; Dobbin, N; St-Jean, M; Wallace, L; Marro, L; Shin, T; You, H; Kulka, R; Allen, R W; Wheeler, A J

    2016-10-01

    Traffic emissions have been associated with a wide range of adverse health effects. Many schools are situated close to major roads, and as children spend much of their day in school, methods to reduce traffic-related air pollutant concentrations in the school environment are warranted. One promising method to reduce pollutant concentrations in schools is to alter the timing of the ventilation so that high ventilation time periods do not correspond to rush hour traffic. Health Canada, in collaboration with the Ottawa-Carleton District School Board, tested the effect of this action by collecting traffic-related air pollution data from four schools in Ottawa, Canada, during October and November 2013. A baseline and intervention period was assessed in each school. There were statistically significant (P < 0.05) reductions in concentrations of most of the pollutants measured at the two late-start (9 AM start) schools, after adjusting for outdoor concentrations and the absolute indoor-outdoor temperature difference. The intervention at the early-start (8 AM start) schools did not have significant reductions in pollutant concentrations. Based on these findings, changing the timing of the ventilation may be a cost-effective mechanism of reducing traffic-related pollutants in late-start schools located near major roads.

  5. Determination of benzene, toluene and xylene concentration in humid air using differential ion mobility spectrometry and partial least squares regression.

    PubMed

    Maziejuk, M; Szczurek, A; Maciejewska, M; Pietrucha, T; Szyposzyńska, M

    2016-05-15

    Benzene, toluene and xylene (BTX compounds) are chemicals of greatest concern due to their impact on humans and the environment. In many cases, quantitative information about each of these compounds is required. Continuous, fast-response analysis, performed on site would be desired for this purpose. Several methods have been developed to detect and quantify these compounds in this way. Methods vary considerably in sensitivity, accuracy, ease of use and cost-effectiveness. The aim of this work is to show that differential ion mobility spectrometry (DMS) may be applied for determining concentration of BTX compounds in humid air. We demonstrate, this goal is achievable by applying multivariate analysis of the measurement data using partial least squares (PLS) regression. The approach was tested at low concentrations of these compounds in the range of 5-20 ppm and for air humidity in a range 0-12 g/kg. These conditions correspond to the foreseeable application of the developed approach in occupational health and safety measurements. The average concentration assessment error was about 1 ppm for each: benzene, toluene and xylene. We also successfully determined water vapor content in air. The error achieved was 0.2 g/kg. The obtained results are very promising regarding further development of DMS technique as well as its application.

  6. Investigation of indoor air volatile organic compounds concentration levels in dental settings and some related methodological issues.

    PubMed

    Santarsiero, Anna; Fuselli, Sergio; Piermattei, Alessandro; Morlino, Roberta; De Blasio, Giorgia; De Felice, Marco; Ortolani, Emanuela

    2009-01-01

    The assessment of indoor air volatile organic compounds (VOCs) concentration levels in dental settings has a big health relevance for the potentially massive occupational exposure to a lot of diverse contaminants. The comparison of the VOCs profile relative to indoor conditions and to the corresponding outdoor concentrations, as well as the discovery of possible correlations between specific dental activities and VOCs concentration variations are of utmost importance for offering a reliable characterization of risk for dentists and dental staff health. In this study we review the most relevant environmental studies addressing the VOCs contamination level in dental settings. We analyze the methodological problems this kind of study must face and we report preliminary results of an indoor air investigation, carried out at dental hospital in Italy, the "Ospedale odontoiatrico George Eastman" of Rome, in which general lines for the analysis of dental settings in environmental terms are sketched. The aim of this work is to identify the kind of problems a typical enclosed (non-industrial) environment indoor air investigation has to cope with by means of the analysis of a case study.

  7. Short-term temperature-dependent air-surface exchange and atmospheric concentrations of polychlorinated naphthalenes and organochlorine pesticides

    SciTech Connect

    Lee, R.G.M.; Burnett, V.; Harner, T.; Jones, K.C.

    2000-02-01

    Atmospheric concentrations of five organochlorine (OC) pesticides, some of which have been banned for a number of years, and polychlorinated naphthalenes (PCNs) were measured at a U.K. site over periods of 6 h for 7 days resulting in 28 samples. Mean concentrations of the pesticides were {alpha}-HCH 90 pg m{sup {minus}3}, {gamma}-HCH 500, {rho},{rho}{prime}-DDE 8, dieldrin 63, endrin 22, and HCB 39. PCN mean homologue concentrations were {sub 3}CNs 67 pg m{sup {minus}3}, {sub 4}CNs 78, {sub 5}CNs 5, {sub 6}CNs 0.6, {sub 7}CNs 0.6, and {Sigma}PCNs 152. TEQ concentrations for those PCNs ascribed TEF values ranged between 0.36 and 3.6 fg m{sup {minus}3} which corresponds to {approximately}3.0--30% of the TEQ concentrations of PCDD/Fs at the same site. All the compounds measured, except HCB, exhibited a strong temperature-dependent diurnal cycling. Results from Clausius-Clapeyron plots show that pesticide concentrations were controlled by temperature-driven air-surface recycling throughout the first 5 days when stable atmospheric conditions were dominant, while during the last 2 days advection became more influential as more unstable and cooler weather started to influence the site. PCN concentrations were controlled primarily by a mixture of recycling and advection throughout the first 5 days and then by advection in the final 2 days, suggesting that there are ongoing emissions from diffuse point sources of PCNs into the U.K. atmosphere. This study provides further evidence of the rapid air-surface exchange of semivolatile organic compounds (SOCs) and shows how different factors alone or in combination can produce rapid changes in the atmospheric concentrations of past and present SOCs.

  8. Exposure to concentrated coarse air pollution particles causes mild cardiopulmonary effects in young healthy adults

    EPA Science Inventory

    Rationale: There is ample epidemiological and toxicological evidence that exposure to fme air pollution particles (PM2.5), which are primarily derived from combustion processes, can result in increased mortality and morbidity. There is less certainty as to the contribution of coa...

  9. Vascular Effects of a Subchronic Inhalation Exposure to Concentrated Ambient Air Particles in Atherosclerosis Susceptible Mice

    EPA Science Inventory

    Numerous studies have reported the adverse effects of particulate air pollution on cardiovascular function and disease. The causal physiochemical properties of particles and their mechanisms of action/injury remain unknown. This study examined the vascular effects in 15 wk old ma...

  10. Development and Evaluation of Land-Use Regression Models Using Modeled Air Quality Concentrations

    EPA Science Inventory

    Abstract Land-use regression (LUR) models have emerged as a preferred methodology for estimating individual exposure to ambient air pollution in epidemiologic studies in absence of subject-specific measurements. Although there is a growing literature focused on LUR evaluation, fu...

  11. A modeling framework for characterizing near-road air pollutant concentration at community scales

    EPA Science Inventory

    In this study, we combine information from transportation network, traffic emissions, and dispersion model to develop a framework to inform exposure estimates for traffic-related air pollutants (TRAPs) with a high spatial resolution. A Research LINE source dispersion model (R-LIN...

  12. Biological monitoring of dichloropropene: Air concentrations, urinary metabolite, and renal enzyme excretion

    SciTech Connect

    Osterloh, J.D.; Wang, R.; Schneider, F.; Maddy, K. )

    1989-07-01

    Fifteen applicators of dichloropropene (DCP) were studied for personal air exposure to DCP, excretion of the metabolite of DCP (3CNAC), and excretion of the renal tubular enzyme, N-acetyl glucosaminidase (NAG). Each was studied for four 6-8 h consecutive intervals following baseline determinations of 3CNAC and NAG excretion. In accord with pilot data, 24-h urinary excretion of 3CNAC (mg) correlated well with exposure product for DCP (min exposed.mg/m{sup 3}), r = 0.854, p less than .001. A more precise correlation of the air exposure product with urinary excretion of 3CNAC was discerned by using the morning urine after the previous day of exposure (micrograms/mg of creatinine), r = 0.914, p less than .001. Four workers had clinically elevated activity of NAG (greater than 4 mU/mg creatinine) in any of their urine collections after baseline. Nine workers showed greater than 25% increases in NAG excretion when compared to baseline. Dichloropropene air exposure products of greater than 700 mg.min/m{sup 3} or excretion of greater than 1.5 mg 3CNAC/d distinguished abnormally high daily excretion of NAG. These data demonstrate a firm positive relationship between air exposure and internal exposure, and a possible subclinical nephrotoxic effect in DCP workers.

  13. Existence of a Thermodynamic Spin-Glass Phase in the Zero-Concentration Limit of Anisotropic Dipolar Systems

    NASA Astrophysics Data System (ADS)

    Andresen, Juan Carlos; Katzgraber, Helmut G.; Oganesyan, Vadim; Schechter, Moshe

    2014-10-01

    The nature of ordering in dilute dipolar interacting systems dates back to the work of Debye and is one of the most basic, oldest and as-of-yet unsettled problems in magnetism. While spin-glass order is readily observed in several RKKY-interacting systems, dipolar spin glasses are the subject of controversy and ongoing scrutiny, e.g., in LiHoxY1 -xF4, a rare-earth randomly diluted uniaxial (Ising) dipolar system. In particular, it is unclear if the spin-glass phase in these paradigmatic materials persists in the limit of zero concentration or not. We study an effective model of LiHoxY1 -xF4 using large-scale Monte Carlo simulations that combine parallel tempering with a special cluster algorithm tailored to overcome the numerical difficulties that occur at extreme dilutions. We find a paramagnetic to spin-glass phase transition for all Ho+ ion concentrations down to the smallest concentration numerically accessible, 0.1%, and including Ho+ ion concentrations that coincide with those studied experimentally up to 16.7%. Our results suggest that randomly diluted dipolar Ising systems have a spin-glass phase in the limit of vanishing dipole concentration, with a critical temperature vanishing linearly with concentration. The agreement of our results with mean-field theory testifies to the irrelevance of fluctuations in interactions strengths, albeit being strong at small concentrations, to the nature of the low-temperature phase and the functional form of the critical temperature of dilute anisotropic dipolar systems. Deviations from linearity in experimental results at the lowest concentrations are discussed.

  14. Determining the 95% limit of detection for waterborne pathogen analyses from primary concentration to qPCR

    USGS Publications Warehouse

    Stokdyk, Joel P.; Firnstahl, Aaron; Spencer, Susan K.; Burch, Tucker R; Borchardt, Mark A.

    2016-01-01

    The limit of detection (LOD) for qPCR-based analyses is not consistently defined or determined in studies on waterborne pathogens. Moreover, the LODs reported often reflect the qPCR assay alone rather than the entire sample process. Our objective was to develop an approach to determine the 95% LOD (lowest concentration at which 95% of positive samples are detected) for the entire process of waterborne pathogen detection. We began by spiking the lowest concentration that was consistently positive at the qPCR step (based on its standard curve) into each procedural step working backwards (i.e., extraction, secondary concentration, primary concentration), which established a concentration that was detectable following losses of the pathogen from processing. Using the fraction of positive replicates (n = 10) at this concentration, we selected and analyzed a second, and then third, concentration. If the fraction of positive replicates equaled 1 or 0 for two concentrations, we selected another. We calculated the LOD using probit analysis. To demonstrate our approach we determined the 95% LOD for Salmonella enterica serovar Typhimurium, adenovirus 41, and vaccine-derived poliovirus Sabin 3, which were 11, 12, and 6 genomic copies (gc) per reaction (rxn), respectively (equivalent to 1.3, 1.5, and 4.0 gc L−1 assuming the 1500 L tap-water sample volume prescribed in EPA Method 1615). This approach limited the number of analyses required and was amenable to testing multiple genetic targets simultaneously (i.e., spiking a single sample with multiple microorganisms). An LOD determined this way can facilitate study design, guide the number of required technical replicates, aid method evaluation, and inform data interpretation.

  15. Concentrations of vehicle-related air pollutants in an urban parking garage.

    PubMed

    Kim, Sung R; Dominici, Francesca; Buckley, Timothy J

    2007-11-01

    There is growing evidence that traffic-related air pollution poses a public health threat, yet the dynamics of human exposure are not well understood. The urban parking garage is a microenvironment that is of concern but has not been characterized. Using time-resolved measurement methods, we evaluated air toxics levels within an urban parking garage and assessed the influence of vehicle activity and type on their levels. Carbon monoxide (CO) and particle-bound polycyclic aromatic hydrocarbons (pPAH) were measured with direct-reading instruments. Volatile organic compounds (VOCs) were measured in 30 min intervals using a sorbent tube loaded sequential sampler. Vehicle volume and type were evaluated by video recording. Sampling was conducted from June 24 to July 17, 2002. We observed garage traffic median volumes of 71 counts/h on weekdays and 6 counts/h on weekends. The 12-fold reduction in traffic volume from weekday to weekend corresponded with a decrease in median air pollution that varied from a minimum 2- (CO) to a maximum 7 (pPAH)-fold. The actual 30-min median weekday and weekend values were: CO--2.6/1.2 ppm; pPAH--19/2.6 ng/m(3); 1,3-butadiene-0.5/0.2 microg/m(3), MTBE-7.4/0.4 microg/m(3); and benzene-2.7/0.3 microg/m(3). The influence of traffic was quantified using longitudinal models. The pollutant coefficients provide an indication of the average air pollution vehicle source contribution and ranged from 0.31 (CO) to 1.08 (pPAH) percent increase/vehicle count. For some pollutants, a slightly higher (0.5-0.6%) coefficient was observed for light-trucks relative to cars. This study has public health relevance in providing a unique assessment of air pollution levels and source contribution for the urban parking garage.

  16. Response of ozone to changes in hydrocarbon and nitrogen oxide concentrations in outdoor smog chambers filled with Los Angeles air

    NASA Astrophysics Data System (ADS)

    Kelly, Nelson A.; Gunst, Richard F.

    During the summer portion of the 1987 Southern California Air Quality Study (SCAQS), outdoor smog chamber experiments were performed on Los Angeles air to determine the response of maximum ozone levels, O 3(max), to changes in the initial concentrations of hydrocarbons, HC, and nitrogen oxides, NO x. These captive-air experiments were conducted in downtown Los Angeles and in the downwind suburb of Claremont. Typically, eight chambers were filled with LA air in the morning. In some chambers the initial HC and/or NO x concentrations were changed by 25% to 50% by adding various combinations of a mixture of HC, clean air, or NO x. The O 3 concentration in each chamber was monitored throughout the day to determine O 3(max). An empirical mathematical model for O 3(max) was developed from regression fits to the initial HC and NO x concentrations and to the average daily temperature at both sites. This is the first time that a mathematical expression for the O 3-precursor relationship and the positive effect of temperature on O 3(max) have been quantified using captive-air experiments. An ozone isopleth diagram prepared from the empirical model was qualitatively similar to those prepared from photochemical mechanisms. This constitutes the first solely empirical corroboration of the O 3 contour shape for Los Angeles. To comply with the Federal Ozone Standard in LA, O 3(max) must be reduced by approximately 50%. Several strategies for reducing O 3(max) by 50% were evaluated using the empirical model. For the average initial conditions that we measured in LA, the most efficient strategy is one that reduces HC by 55-75%, depending on the ambient HC/NO x ratio. Any accompanying reduction in NO x would be counter-productive to the benefits of HC reductions. In fact, reducing HC and NO x simultaneously requires larger percentage reductions for both than the reduction required when HC alone is reduced. The HC-reduction strategy is the most efficient on average, but no single

  17. The GIS-based SafeAirView software for the concentration assessment of radioactive pollutants after an accidental release.

    PubMed

    Canepa, Elisa; D'Alberti, Francesco; D'Amati, Francesco; Triacchini, Giuseppe

    2007-02-01

    The European Commission Joint Research Centre (JRC) in Ispra (Italy) has long been running nuclear installations for research purposes. The Nuclear Decommissioning and Facilities Management Unit (NDFM) is responsible for the surveillance of radioactivity levels in nuclear emergency conditions. The NDFM Unit has commissioned the implementation of a specifically developed decision support system, which can be used for quick emergency evaluation in the case of hypothetical accident and for emergency exercises. The requisites were to be a user-friendly software, able to quickly calculate and display values of air and ground radioactive contamination in the complex area around JRC, following an accidental release of radioactive substances from a JRC nuclear research installation. The developed software, named "SafeAirView", is an advanced implementation of GIS technology applied to an existing MS-DOS mode dispersion model, SAFE_AIR (Simulation of Air pollution From Emissions_Above Inhomogeneous Regions). SAFE_AIR is a numerical model which simulates transport, diffusion, and deposition of airborne pollutants emitted in the low atmosphere above complex orography at both local and regional scale, under non-stationary and inhomogeneous emission and meteorological conditions. SafeAirView makes use of user-friendly MS-Windows type interface which drives the dispersion model by a sequential and continuous input-output process, allowing a real time simulation. The GIS environment allows a direct interaction with the territory elements in which the simulation takes place, using data for the JRC Ispra region represented in geo-referenced cartography. Furthermore it offers the possibility to relate concentrations with population distribution and other geo-referenced maps, in a geographic view. Output concentration and deposition patterns can be plotted and/or exported. In spite of the selected specific databases, the SafeAirView software architecture is a general structure

  18. Toxicity of atrazine, glyphosate, and quinclorac in bullfrog tadpoles exposed to concentrations below legal limits.

    PubMed

    Dornelles, M F; Oliveira, G T

    2016-01-01

    This work sought to ascertain survival and possible changes in levels of glycogen, triglycerides, total lipids, cholesterol, protein, and lipid peroxidation in gills, liver, and muscle of bullfrog tadpoles (Lithobates catesbeianus) exposed to low concentrations of atrazine (2.5 μg L(-1)), glyphosate (18 μg L(-1)), and quinclorac (0.025 μg L(-1)) at laboratorial conditions. Tadpoles showed a reduction of glycogen and triglyceride in all organs and an increase in lipid peroxidation (LPO) compared with control animals. Total lipid in gills and muscle increased in exposure to atrazine, and gills alone in exposure to glyphosate, but decreased in gills, liver, and muscle after quinclorac. Cholesterol increased in gills and liver after atrazine, in gills and muscle after glyphosate, and decreased in liver after quinclorac. Total protein in gills decreased after exposure to all herbicides, increased in muscle after atrazine, and in liver and muscle after quinclorac. These findings show that at concentrations of these herbicides tested can lead to an increase in energy expenditure to maintain homeostasis and survival of these animals despite the increase in lipid peroxidation levels in all organs analyzed. Responses observed can be one of the factors responsible for the decline in the number of amphibians around the world.

  19. Understand the limitations of air/water testing of distillation equipment

    SciTech Connect

    Bennett, D.L.; Ludwig, K.A. )

    1994-04-01

    Distillation continues to be a unit operation of major importance--and a dynamic area for technical development. The designs of trays and packings are rapidly evolving, and the application of equipment also is changing. As chemical processes are pushed to become more efficient and lower cost, a general reduction in the traditional values for equipment safety factors are being seen. The net results is that one now has a greater need for a more thorough and fundamental understanding of distillation equipment. One technique to improve the understanding of distillation equipment is air/water testing. Such testing of distillation trays has become very common, and air/water test results for packed columns also are being reported. In this article, the authors will provide some guidance on how to assess the validity of such tests to industrial applications. In addition, they will discuss several possible approaches to test--and develop confidence in--the design of distillation equipment.

  20. Particle Concentrations and Effectiveness of Free-Standing Air Filters in Bedrooms of Children with Asthma in Detroit, Michigan

    PubMed Central

    Du, Liuliu; Batterman, Stuart; Parker, Edith; Godwin, Christopher; Chin, Jo-Yu; O'Toole, Ashley; Robins, Thomas; Brakefield-Caldwell, Wilma; Lewis, Toby

    2011-01-01

    Asthma can be exacerbated by environmental factors including airborne particulate matter (PM) and environmental tobacco smoke (ETS). We report on a study designed to characterize PM levels and the effectiveness of filters on pollutant exposures of children with asthma. 126 households with an asthmatic child in Detroit, Michigan, were recruited and randomized into control or treatment groups. Both groups received asthma education; the latter also received a free-standing high efficiency air filter placed in the child’s bedroom. Information regarding the home, emission sources, and occupant activities was obtained using surveys administered to the child's caregiver and a household inspection. Over a one-week period, we measured PM, carbon dioxide (CO2), environmental tobacco smoke (ETS) tracers, and air exchange rates (AERs). Filters were installed at midweek. Before filter installation, PM concentrations averaged 28 µg m−3, number concentrations averaged 70,777 and 1,471 L−1 in 0.3–1.0 and 1–5 µm size ranges, respectively, and the median CO2 concentration was 1,018 ppm. ETS tracers were detected in 23 of 38 homes where smoking was unrestricted and occupants included smokers and, when detected, PM concentrations were elevated by an average of 15 µg m−3. Filter use reduced PM concentrations by an average of 69 to 80%. Simulation models representing location conditions show that filter air flow, room volume and AERs are the key parameters affecting PM removal, however, filters can achieve substantial removal in even "worst" case applications. While PM levels in homes with asthmatic children can be high, levels can be dramatically reduced using filters. PMID:21874085

  1. [Air negative ion concentration in different modes of courtyard forests in southern mountainous areas of Jinan, Shandong Province of East China].

    PubMed

    Wang, Xiao-Lei; Li, Chuan-Rong; Xu, Jing-Wei; Hu, Ding-Meng; Zhao, Zhen-Lei; Zhang, Liu-dong

    2013-02-01

    Taking five typical courtyard forests and a non-forest courtyard in southern mountains areas of Jinan as test objects, a synchronous observation was conducted on the air negative ion concentration and related meteorological factors in March-December, 2010. The air negative ion concentration in the test courtyards showed an obvious seasonal variation, being in the order of summer > autumn > spring > winter. The diurnal variation of the air negative ion concentration presented a double peak curve, with the maximum in 10:00 - 11:00 and 16:00 - 17:00 and the minimum around 12:00. The daily air quality was the best at 10:00 and 16:00, and better in afternoon than in the morning. Summer time and garden sketch mode had the best air quality in a year. The mean annual air negative ion and the coefficient of air ion (CI) of the test courtyards were in the order of garden sketch > economic fruit forest > natural afforested forest > flowers and bonsai > farm tourist > non-forest, with the air negative ion concentration being 813, 745, 695, 688, 649, and 570 ions.cm-3, and the CI being 1.22, 1.11, 0.85, 0.84, 0.83, and 0.69, respectively. It could be concluded that garden sketch was the ideal courtyard forest mode. The air negative ion concentration was significantly positively correlated with air temperature and relative humidity, but irrelevant to light intensity.

  2. Experimental Limiting Oxygen Concentrations for Nine Organic Solvents at Temperatures and Pressures Relevant to Aerobic Oxidations in the Pharmaceutical Industry

    PubMed Central

    2015-01-01

    Applications of aerobic oxidation methods in pharmaceutical manufacturing are limited in part because mixtures of oxygen gas and organic solvents often create the potential for a flammable atmosphere. To address this issue, limiting oxygen concentration (LOC) values, which define the minimum partial pressure of oxygen that supports a combustible mixture, have been measured for nine commonly used organic solvents at elevated temperatures and pressures. The solvents include acetic acid, N-methylpyrrolidone, dimethyl sulfoxide, tert-amyl alcohol, ethyl acetate, 2-methyltetrahydrofuran, methanol, acetonitrile, and toluene. The data obtained from these studies help define safe operating conditions for the use of oxygen with organic solvents. PMID:26622165

  3. Spatial and seasonal variation in volatile compounds air concentrations in a hemiboreal mixed forest.

    NASA Astrophysics Data System (ADS)

    Noe, Steffen M.; Hüve, Katja; Niinemets, Ülo; Copolovici, Lucian

    2013-04-01

    The seasonal and vertical distribution of ambient biogenic volatile organic compounds (BVOC) concentrations within a hemiboreal forest canopy was investigated over a period of one year. Variability in temporal and spatial terpene concentrations spanned over a wide range. Specially stress related emissions lead to very high ambient concentrations in dry and hot summer months. Seasonal differences in the share of different monoterpenes were found. During summer months, dominance of α-pinene in the lower and of limonene in the upper part of the canopy was observed, both accounting for up to 70 % of the total monoterpene concentration. During wintertime, Δ3-carene was the dominant species, accounting for 60 % of total monoterpene concentration in January. Spatially, the possible sources of biogenic monoterpenes are beside foliage the leaf litter and top soil as well as resins exuding from stems.

  4. Industrial sources influence air concentrations of hydrogen sulfide and sulfur dioxide in rural areas of western Canada.

    PubMed

    Burstyn, Igor; Senthilselvan, Ambikaipakan; Kim, Hyang-Mi; Cherry, Nicola M; Pietroniro, Elise; Waldner, Cheryl

    2007-10-01

    A survey of monthly average concentrations of sulfur dioxide (SO2) and hydrogen sulfide (H2S) at rural locations in western Canada (provinces of Alberta, British Columbia, and Saskatchewan) was conducted in 2001-2002, as part of an epidemiological study of the effects of oil and gas industry emissions on the health of cattle. Repeated measurements were obtained at some months and locations. We aimed to develop statistical models of the effect of oil and gas infrastructure on air concentrations. The regulatory authorities supplied the information on location of the different oil and gas facilities during the study period and, for Alberta, provided data on H2S content of wells and flaring volumes. Linear mixed effects models were used to relate observed concentrations to proximity and type of oil and gas infrastructure. Low concentrations were recorded; the monthly geometric mean was 0.1-0.2 ppb for H2S, and 0.3-1.3 ppb for SO2. Substantial variability between repeated measurements was observed. The precision of the measurement method was 0.005 ppb for both contaminants. There were seasonal trends in the concentrations, but the spatial variability was greater. This was explained, in part, by proximity to oil/gas/bitumen wells and (for SO2) gas plants. Wells within 2 km of monitoring stations had the greatest impact on measured concentrations. For H2S, 8% of between-location variability was explained by proximity to industrial sources of emissions; for SO2 this proportion was 18%. In Alberta, proximity to sour gas wells and flares was associated with elevated H2S concentrations; however, the estimate of the effect of sour gas wells in the immediate vicinity of monitoring stations was unstable. Our study was unable to control for all possible sources of the contaminants. However, the results suggest that oil and gas extraction activities contribute to air pollution in rural areas of western Canada. PMID:17972769

  5. Dynamic simulation of concentrated macromolecular solutions with screened long-range hydrodynamic interactions: Algorithm and limitations

    PubMed Central

    Ando, Tadashi; Chow, Edmond; Skolnick, Jeffrey

    2013-01-01

    Hydrodynamic interactions exert a critical effect on the dynamics of macromolecules. As the concentration of macromolecules increases, by analogy to the behavior of semidilute polymer solutions or the flow in porous media, one might expect hydrodynamic screening to occur. Hydrodynamic screening would have implications both for the understanding of macromolecular dynamics as well as practical implications for the simulation of concentrated macromolecular solutions, e.g., in cells. Stokesian dynamics (SD) is one of the most accurate methods for simulating the motions of N particles suspended in a viscous fluid at low Reynolds number, in that it considers both far-field and near-field hydrodynamic interactions. This algorithm traditionally involves an O(N3) operation to compute Brownian forces at each time step, although asymptotically faster but more complex SD methods are now available. Motivated by the idea of hydrodynamic screening, the far-field part of the hydrodynamic matrix in SD may be approximated by a diagonal matrix, which is equivalent to assuming that long range hydrodynamic interactions are completely screened. This approximation allows sparse matrix methods to be used, which can reduce the apparent computational scaling to O(N). Previously there were several simulation studies using this approximation for monodisperse suspensions. Here, we employ newly designed preconditioned iterative methods for both the computation of Brownian forces and the solution of linear systems, and consider the validity of this approximation in polydisperse suspensions. We evaluate the accuracy of the diagonal approximation method using an intracellular-like suspension. The diffusivities of particles obtained with this approximation are close to those with the original method. However, this approximation underestimates intermolecular correlated motions, which is a trade-off between accuracy and computing efficiency. The new method makes it possible to perform large-scale and

  6. A gravimetric approach to providing SI traceability for concentration measurement results of mercury vapor at ambient air levels

    NASA Astrophysics Data System (ADS)

    Ent, Hugo; van Andel, Inge; Heemskerk, Maurice; van Otterloo, Peter; Bavius, Wijnand; Baldan, Annarita; Horvat, Milena; Brown, Richard J. C.; Quétel, Christophe R.

    2014-11-01

    Current measurement and calibration capabilities for mercury vapor in air are maintained at levels of 0.2-40 μg Hg m-3. In this work, a mercury vapor generator has been developed to establish metrological traceability to the international system of units (SI) for mercury vapor measurement results ≤15 ng Hg m-3, i.e. closer to realistic ambient air concentrations (1-2 ng Hg m-3) [1]. Innovations developed included a modified type of diffusion cell, a new measurement method to weigh the loss in (mercury) mass of these diffusion cells during use (ca. 6-8 μg mass difference between successive weighings), and a new housing for the diffusion cells to maximize flow characteristics and to minimize temperature variations and adsorption effects. The newly developed mercury vapor generator system was tested by using diffusion cells generating 0.8 and 16 ng Hg min-1. The results also show that the filter system, to produce mercury free air, is working properly. Furthermore, and most importantly, the system is producing a flow with a stable mercury vapor content. Some additional improvements are still required to allow the developed mercury vapor generator to produce SI traceable mercury vapor concentrations, based upon gravimetry, at much lower concentration levels and reduced measurement uncertainties than have been achieved previously. The challenges to be met are especially related to developing more robust diffusion cells and better mass measurement conditions. The developed mercury vapor generator will contribute to more reliable measurement results of mercury vapor at ambient and background air levels, and also to better safety standards and cost reductions in industrial processes, such as the liquefied natural gas field, where aluminum main cryogenic heat exchangers are used which are particularly prone to corrosion caused by mercury.

  7. A pilot study to assess ground-level ambient air concentrations of fine particles and carbon monoxide in urban Guatemala.

    PubMed

    Shendell, Derek G; Naeher, Luke P

    2002-11-01

    Ambient concentrations and the elemental composition of particles less than 2.5 microm in diameter (PM2.5), as well as carbon monoxide (CO) concentrations, were measured at ground-level in three Guatemalan cities in summer 1997: Guatemala City, Quetzaltenango, and Antigua. This pilot study also included quantitative and qualitative characterizations of microenvironment conditions, e.g., local meteorology, reported elsewhere. The nondestructive X-ray fluorescence elemental analysis (XRF) of Teflon filters was conducted. The highest integrated average PM2.5. concentrations in an area (zona) of Guatemala City and Quetzaltenango were 150 microg m(-3) (zona 12) and 120 microg m(-3) (zona 2), respectively. The reported integrated average PM2.5 concentration for Antigua was 5 microg m(-3). The highest observed half-hour and monitoring period average CO concentrations in Guatemala City were 10.9 ppm (zona 8) and 7.2 ppm (zonas 8 and 10), respectively. The average monitoring period CO concentration in Antigua was 2.6 ppm. Lead and bromine concentrations were negligible, indicative of the transition to unleaded fuel use in cars and motorcycles. The XRF results suggested sources of air pollution in Guatemala, where relative rankings varied by city and by zonas within each city, were fossil fuel combustion emitting hydrocarbons, combustion of sulfurous conventional fuels, soil/roadway dust, farm/agricultural dust, and vehicles (evaportion of gas, parts' wear).

  8. Polystyrene-poly(ethylene oxide) diblock copolymer: the effect of polystyrene and spreading concentration at the air/water interface.

    PubMed

    Glagola, Cameron P; Miceli, Lia M; Milchak, Marissa A; Halle, Emily H; Logan, Jennifer L

    2012-03-20

    Polystyrene-block-poly(ethylene oxide) (PS-PEO) is an amphiphilic diblock copolymer that undergoes microphase separation when spread at the air/water interface, forming nanosized domains. In this study, we investigate the impact of PS by examining a series of PS-PEO samples containing constant PEO (~17,000 g·mol(-1)) and variable PS (from 3600 to 200,000 g·mol(-1)) through isothermal characterization and atomic force microscopy (AFM). The polymers separated into two categories: predominantly hydrophobic and predominantly hydrophilic with a weight percent of PEO of ~20% providing the boundary between the two. AFM results indicated that predominantly hydrophilic PS-PEO forms dots while more hydrophobic samples yield a mixture of dots and spaghetti with continent-like structures appearing at ~7% PEO or less. These structures reflect a blend of polymer spreading, entanglement, and vitrification as the solvent evaporates. Changing the spreading concentration provides insight into this process with higher concentrations representing earlier kinetic stages and lower concentrations demonstrating later ones. Comparison of isothermal results and AFM analysis shows how polymer behavior at the air/water interface correlates with the observed nanostructures. Understanding the impact of polymer composition and spreading concentration is significant in leading to greater control over the nanostructures obtained through PS-PEO self-assembly and their eventual application as polymer templates.

  9. Comparison of Ambient Radon Concentrations in Air in the Northern Mojave Desert from Continuous and Integrating Instruments

    SciTech Connect

    David S. Shafer; David McGraw; Lynn H. Karr; Greg McCurdy; Tammy L. Kluesner; Karen J. Gray; Jeffrey Tappen

    2010-05-18

    As part of a program to characterize and baseline environmental parameters, ambient radon-222 (Rn) monitoring was conducted in the rural community of Amargosa Valley, NV, the closest community to Yucca Mountain. Passive integrating and continuous Rn monitoring instruments were deployed adjacent to the Community Environmental Monitoring Program (CEMP) station in Amargosa Valley. The CEMP station provided real-time ambient gamma exposure and meteorological data used to correct the integrated Rn measurements, verified the meteorological data collected by the continuous Rn monitoring instrument, and for provided instrumentation for evaluating the relationships between meteorological conditions and Rn concentrations. Hourly Rn concentrations in air measured by the continuous Rn monitoring instrument (AlphaGUARD®) were compared to the average hourly values for the integrating Rn measurements (E-PERM®) by dividing the total Rn measurements by the number of hours the instruments were deployed. The results of the comparison indicated that average hourly ambient Rn concentrations as measured by both methods ranged from 0.2 to 0.4 pico-curies per liter of air. Ambient Rn values for the AlphaGUARD exhibited diurnal variations. When Rn concentrations were compared with measurements of temperature (T), barometric pressure, and relative humidity, the correlation (inversely) was highest with T, albeit weakly.

  10. An assessment of indoor air concentrations and health risks of volatile organic compounds in three primary schools.

    PubMed

    Sofuoglu, Sait C; Aslan, Guler; Inal, Fikret; Sofuoglu, Aysun

    2011-01-01

    Concentrations of volatile organic compounds (VOCs), including formaldehyde, in classrooms, kindergartens, and outdoor playgrounds of three primary schools were measured in spring, winter, and fall terms in İzmir, Turkey. A health-risk assessment was conducted for odor detection, sensory irritation, chronic toxic effects, and cancer. Active sampling was applied for VOCs and formaldehyde on Tenax TA and DNPH tubes, respectively. VOCs were analyzed in a thermal desorption-GC-MS system. Formaldehyde analysis was performed using an HPLC instrument. Benzene, toluene, and formaldehyde were the most abundant compounds with 95th percentile indoor air concentrations of 29, 87, and 106 μg/m(3), respectively. Naphthalene and xylenes followed them with an order of magnitude lower concentrations. Two isomers of dichlorobenzene (1,3 and 1,4) were the other notable compounds. The concentrations were utilized to classify the indoor air pollutants with respect to potential health effects. In addition, carcinogenic and chronic toxic risks were estimated using Monte-Carlo simulation. Formaldehyde appears to be the most concerning pollutant with high chronic toxic and carcinogenic risk levels according to the health assessment followed by naphthalene, benzene, and toluene due to their chronic effects.

  11. Ambient air concentration of sulfur dioxide affects flight activity in bees

    SciTech Connect

    Ginevan, M.E.; Lane, D.D.; Greenberg, L.

    1980-10-01

    Three long-term (16 to 29 days) low-level (0.14 to 0.28 ppM) sulfur dioxide fumigations showed that exposure tothis gas has deleterious effects on male sweat bees (Lasioglossum zephrum). Although effects on mortality were equivocal, flight activity was definitely reduced. Because flight is necessary for successful mating behavior, the results suggest that sulfur dioxide air pollution could adversely affect this and doubtless other terrestrial insects.

  12. Sources, Concentrations and Risks of Naphthalene in Indoor and Outdoor Air

    PubMed Central

    Batterman, Stuart; Chin, Jo-Yu; Jia, Chunrong; Godwin, Christopher; Parker, Edith; Robins, Thomas; Max, Paul; Lewis, Toby

    2011-01-01

    Naphthalene is a ubiquitous pollutant, and very high concentrations are sometimes encountered indoors when this chemical is used as a pest repellent or deodorant. This study describes the distribution and sources of vapor phase naphthalene concentrations in four communities in southeast Michigan, USA. Outdoors, naphthalene was measured in the communities and at a near-road site. Indoors, naphthalene levels were characterized in 288 suburban and urban homes. The median outdoor concentration was 0.15 µg m−3, and a modest contribution from rush-hour traffic was noted. The median indoor long-term concentration was 0.89 µg m−3, but concentrations were extremely skewed and 14% of homes exceeded 3 µg m−3, the chronic reference concentration for non-cancer effects, 8% exceeded 10 µg m−3, and levels reached 200 µg m−3. The typical individual lifetime cancer risk was about 10−4, and reached 10−2 in some homes. Important sources include naphthalene's use as a pest repellent and deodorant, migration from attached garages, and to lesser extents, cigarette smoke and vehicle emissions. Excessive use as a repellent caused the highest concentrations. Naphthalene presents high risks in a subset of homes, and policies and actions to reduce exposures, e.g., sales bans or restrictions, improved labeling and consumer education, should be considered. PMID:22145682

  13. Concentrations and Risks of p-Dichlorobenzene in Indoor and Outdoor Air

    PubMed Central

    Chin, Jo-Yu; Godwin, Christopher; Jia, Chunrong; Robins, Thomas; Lewis, Toby; Parker, Edith; Max, Paul; Batterman, Stuart

    2012-01-01

    p-Dichlorobenzene (PDCB) is a chlorinated volatile organic compound (VOC) that can be encountered at high concentrations in buildings due to its use as pest repellent and deodorant. This study characterizes PDCB concentrations in four communities in southeast Michigan. The median concentration outside 145 homes was 0.04 µg m−3, and the median concentration inside 287 homes was 0.36 µg m−3. The distribution of indoor concentrations was extremely skewed. For example, 30% of the homes exceeded 0.91 µg m−3, which corresponds to a cancer risk level of 10−5 based on the California unit risk estimate, and 4% of homes exceeded 91 µg m−3, equivalent to a 10−3 risk level. The single highest measurement was 4,100 µg m−3. Estimates of whole house emission rates were largely consistent with chamber test results in the literature. Indoor concentrations that exceed a few µg m−3 indicate use of PDCB products. PDCB concentrations differed among households and the four cities, suggesting the importance of locational, cultural and behavioral factors in the use patterns of this chemical. The high PDCB levels found suggest the need for policies and actions to lower exposures, e.g., sales or use restrictions, improved labeling, and consumer education. PMID:22725685

  14. Effects of radiation and compression on propagating spherical flames of methane/air mixtures near the lean flammability limit

    SciTech Connect

    Chen, Zheng

    2010-12-15

    Large discrepancies between the laminar flame speeds and Markstein lengths measured in experiments and those predicted by simulations for ultra-lean methane/air mixtures bring a great concern for kinetic mechanism validation. In order to quantitatively explain these discrepancies, a computational study is performed for propagating spherical flames of lean methane/air mixtures in different spherical chambers using different radiation models. The emphasis is focused on the effects of radiation and compression. It is found that the spherical flame propagation speed is greatly reduced by the coupling between thermal effect (change of flame temperature or unburned gas temperature) and flow effect (inward flow of burned gas) induced by radiation and/or compression. As a result, for methane/air mixtures near the lean flammability limit, the radiation and compression cause large amounts of under-prediction of the laminar flame speeds and Markstein lengths extracted from propagating spherical flames. Since radiation and compression both exist in the experiments on ultra-lean methane/air mixtures reported in the literature, the measured laminar flame speeds and Markstein lengths are much lower than results from simulation and thus cannot be used for kinetic mechanism validation. (author)

  15. 75 FR 64673 - Approval and Promulgation of Air Quality Implementation Plans; Delaware; Limiting Emissions of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-20

    ...) antiperspirants or deodorants, (5) charcoal lighter materials, and (6) floor wax strippers. Regulation 1141... Emissions of Volatile Organic Compounds From Consumer Products AGENCY: Environmental Protection Agency (EPA... 1141 (formerly SIP Regulation No. 41)--Limiting Emissions of Volatile Organic Compounds from ]...

  16. Limitations of the whole cell patch clamp technique in the control of intracellular concentrations.

    PubMed Central

    Mathias, R T; Cohen, I S; Oliva, C

    1990-01-01

    Recent experimental studies (Pusch and Neher, 1988) and theoretical studies (Oliva et al., 1988) have found that the pipette tip is a significant barrier to diffusion in the whole cell patch clamp configuration. In this paper, we extend the theoretical analysis of fluxes between the pipette and cell to include transmembrane fluxes. The general conclusions are: (a) within the pipette, ion fluxes are driven primarily by diffusion rather than voltage gradients. (b) At steady state there is a concentration difference between the bulk pipette and intracellular solution that is described by delta c = jRp/Dp, where delta c = 1 mM for a flux, j = 1 fmol/s, through a pipette of resistance, Rp = 1 M omega, filled with a solution of resistivity, p = 100 omega --cm, given a solute diffusion coefficient, D = 10(-5) cm2/s. (c) The time to steady state is always accelerated by membrane transport, regardless of the direction of transport. We apply our analysis to the measurement of transport by the Na/K pump and Na/Ca exchanger in cells from the ventricles of mammalian heart. We find that the binding curve for intracellular Na+ to the Na/K pump will appear significantly less steep and more linear if one does not correct for the concentration difference between intracellular and pipette Na+. Similar shifts in the binding curve for extracellular Na+ to the Na/Ca exchanger can occur due to depletion of intracellular Ca(+)+ when the exchanger is stimulated. Lastly, in Appendix we analyze the effects of mobile and fixed intracellular buffers on the movement of Ca(+)+ between the pipette and cell. Fixed buffers greatly slow the time for equilibration of pipette and intracellular Ca(+)+. Mobile buffers act like a shuttle system, as they carry Ca(+)+ from pipette to cell then diffuse back when they are empty. Vigorous transport by the Na/Ca exchanger depletes mobile buffered calcium, thus stimulating diffusion from the pipette to match the rate of Ca(+)+ transport. Moreover, we find that

  17. The flammability limits of lean fuel-air mixtures: thermochemical and kinetic criteria for explosion hazards.

    PubMed

    Burgess, D; Hertzberg, M

    1975-01-01

    The present state of knowledge is reviewed concisely in terms of the experimental methods used, the effect of apparatus size, accuracy of data, methods of data presentation, and the sensitivity of the limits to initial temperature and pressure. The heat of combustion per mole of gas mixture at the lean limit is a reliable thermochemical criterion for the flammability of organic fuels with comparable reactivities. The limit calorific value for the heavy paraffins is 11.5 +/- 0.1 kcal mole -1. However, kinetic effects strongly influence this value. Highly reactive fuels (hydrogen, acetylene) require lower energy contents, whereas less reactive fuels (ammonia) require higher values. Hydrogen-starved fuels (carbon monoxide, cyanogen) show marked anomalies and are sensitive to impurities that can provide H-atom chain carriers. These kinetic effects are reflected in the experimentally measurable burning velocity of the fuel. This parameter is a key ingredient in the theory of flammable limits, which is briefly sketched. Five competing processes dissipate power from the combustion wave and quench it at some characteristic limit velocity. The prevalent consensus that the limits are controlled by natural convection is clearly demonstrated, and the complex interplay of kinetics and thermochemistry follows logically therefrom.

  18. Fermentation of High Concentrations of Maltose by Saccharomyces cerevisiae Is Limited by the COMPASS Methylation Complex▿

    PubMed Central

    Houghton-Larsen, Jens; Brandt, Anders

    2006-01-01

    In Saccharomyces cerevisiae, genes encoding maltose permeases and maltases are located in the telomeric regions of different chromosomes. The COMPASS methylation complex, which methylates lysine 4 on histone H3, controls the silencing of telomeric regions. Yeast strains deleted for SWD1, SWD3, SDC1, SET1, BRE2, or SPP1, encoding components of the COMPASS complex, fermented a medium containing 22% maltose with noticeably higher attenuation than did the wild type, resulting in production of up to 29% more ethanol. The least effective strain was spp1. Absence of COMPASS components had no effect on the fermentation of media with 20% glucose, 20% sucrose, or 16% maltose. Deletion of SWD3 resulted in larger amounts of MAL12 transcript, encoding maltase, at the late stages of fermentation of 22% maltose. A similar effect on maltase activity and maltose uptake capability was seen. The lysine 4 residue of histone H3 was trimethylated in wild-type cells at the late stages, while only small amounts of the dimethylated form were detected. Trimethylation and dimethylation of this residue were not detected in strains deleted for SWD1, SWD3, SET1, BRE2, or SDC1. Trimethylated lysine 4 was apparent only at the early stages (48 and 96 h) of fermentation in an spp1 strain. This work indicates that the COMPASS complex represses the expression of maltose utilization genes during the late stages of fermentation of a high concentration of maltose. PMID:16980427

  19. Mucus secretion by the freshwater snail Lymnaea stagnalis limits aluminum concentrations of the aqueous environment

    SciTech Connect

    Jugdaohsingh, R.; Thompson, R.P.H.; Powell, J.J.; Campbell, M.M.; Mccrohan, C.R.; White, K.N.

    1998-09-01

    Extracellular mucopolysaccharide (EPS) is a significant component in many waters. Its role in the cycling and mobilization of metals is unclear. In vitro studies were conducted to examine the influence of EPS, secreted by the freshwater pond snail, Lymnaea stagnalis, on soluble water Al concentrations at near-neutral pH. Snails maintained in aerated water of known ion content and added aluminum reduced Al in solution as compared to controls. Although snails accumulated Al into soft tissue, this only accounted for a small percentage of the total reduction. The remaining Al was recovered following acidification of the water. This observation was attributed to pedal EPS secreted by L. stagnalis which is chiefly insoluble and substrate bound. The Al that remained in solution was more labile, possibly due to the influence of soluble EPS. Further experiments with isolated EPS, confirmed that this poorly soluble film binds and reduces Al in solution. The influence of EPS on the solution chemistry and bioavailability of Al and possibly other metals may be important in natural waters.

  20. Techniques of low technology sampling of air pollution by metals: a comparison of concentrations and map patterns.

    PubMed

    Lloyd, O L; Gailey, F A

    1987-07-01

    During a 17 month survey of air pollution in the town of Armadale, central Scotland, the concentrations of some metals (iron, manganese, zinc, lead, copper, chrome, nickel, cadmium, and cobalt) were measured in seven types of low technology sampler--four indigenous and three transplanted--at 47 sites. The geographical patterns of the concentrations in the samplers were compared on two types of map. For most metals, sites with high concentrations were present close to the foundry and also in the north of the town. The differences between the patterns of pollution shown by the various types of sampler probably reflected differing mechanisms for collection and different affinities for various sizes and types of metal particle.

  1. Prediction of hydrodynamics and chemistry of confined turbulent methane-air frames in a two concentric tube combustor

    NASA Technical Reports Server (NTRS)

    Markatos, N. C.; Spalding, D. B.; Srivatsa, S. K.

    1978-01-01

    A formulation of the governing partial differential equations for fluid flow and reacting chemical species in a two-concentric-tube combustor is presented. A numerical procedure for the solution of the governing differential equations is described and models for chemical-equilibrium and chemical-kinetics calculations are presented. The chemical-equilibrium model is used to characterize the hydrocarbon reactions. The chemical-kinetics model is used to predict the concentrations of the oxides of nitrogen. The combustor considered consists of two coaxial ducts. Concentric streams of gaseous fuel and air enter the inlet duct at one end; the flow then reverses and flows out through the outer duct. Two sample cases with specified inlet and boundary conditions are considered and the results are discussed.

  2. Dissolved methane concentration profiles and air-sea fluxes from 41°S to 27°N

    NASA Astrophysics Data System (ADS)

    Kelley, Cheryl A.; Jeffrey, Wade H.

    2002-07-01

    Water column samples from a transect cruise from southern Chile through the Panama Canal to the Gulf of Mexico were used to determine dissolved methane depth profiles and air-sea methane fluxes. In the Gulf of Mexico, surface concentrations were approximately 40% supersaturated with respect to the atmosphere, whereas near the equator and in the Peru upwelling region, 10-20% supersaturation generally occurred. These saturation ratios translate into an average flux of methane from the sea surface to the atmosphere of 0.38 μmol m-2 d-1. In addition, water column profiles of dissolved methane indicate that subsurface maxima in dissolved methane concentrations are a consistent feature of the open ocean, except near the equator. At the equator, the subsurface peak at the base of the mixed layer may be bowed down by the Equatorial Undercurrent. The highest methane concentration (12 nM) was observed in the Peru upwelling region.

  3. The CO2 concentrating mechanism and photosynthetic carbon assimilation in limiting CO2 : how Chlamydomonas works against the gradient.

    PubMed

    Wang, Yingjun; Stessman, Dan J; Spalding, Martin H

    2015-05-01

    The CO2 concentrating mechanism (CCM) represents an effective strategy for carbon acquisition that enables microalgae to survive and proliferate when the CO2 concentration limits photosynthesis. The CCM improves photosynthetic performance by raising the CO2 concentration at the site of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), simultaneously enhancing carbon fixation and suppressing photorespiration. Active inorganic carbon (Ci) uptake, Rubisco sequestration and interconversion between different Ci species catalyzed by carbonic anhydrases (CAs) are key components in the CCM, and an array of molecular regulatory elements is present to facilitate the sensing of CO2 availability, to regulate the expression of the CCM and to coordinate interplay between photosynthetic carbon metabolism and other metabolic processes in response to limiting CO2 conditions. This review intends to integrate our current understanding of the eukaryotic algal CCM and its interaction with carbon assimilation, based largely on Chlamydomonas as a model, and to illustrate how Chlamydomonas acclimates to limiting CO2 conditions and how its CCM is regulated.

  4. Comparative microarray analysis and pulmonary changes in Brown Norway rats exposed to ovalbumin and concentrated air particulates.

    PubMed

    Heidenfelder, Brooke L; Reif, David M; Harkema, Jack R; Cohen Hubal, Elaine A; Hudgens, Edward E; Bramble, Lori A; Wagner, James G; Morishita, Masako; Keeler, Gerald J; Edwards, Stephen W; Gallagher, Jane E

    2009-03-01

    The interaction between air particulates and genetic susceptibility has been implicated in the pathogenesis of asthma. The overall objective of this study was to determine the effects of inhalation exposure to environmentally relevant concentrated air particulates (CAPs) on the lungs of ovalbumin (ova) sensitized and challenged Brown Norway rats. Changes in gene expression were compared with lung tissue histopathology, morphometry, and biochemical and cellular parameters in bronchoalveolar lavage fluid (BALF). Ova challenge was responsible for the preponderance of gene expression changes, related largely to inflammation. CAPs exposure alone resulted in no significant gene expression changes, but CAPs and ova-exposed rodents exhibited an enhanced effect relative to ova alone with differentially expressed genes primarily related to inflammation and airway remodeling. Gene expression data was consistent with the biochemical and cellular analyses of the BALF, the pulmonary pathology, and morphometric changes when comparing the CAPs-ova group to the air-saline or CAPs-saline group. However, the gene expression data were more sensitive than the BALF cell type and number for assessing the effects of CAPs and ova versus the ova challenge alone. In addition, the gene expression results provided some additional insight into the TGF-beta-mediated molecular processes underlying these changes. The broad-based histopathology and functional genomic analyses demonstrate that exposure to CAPs exacerbates rodents with allergic inflammation induced by an allergen and suggests that asthmatics may be at increased risk for air pollution effects. PMID:19176365

  5. Biomonitoring urban air pollution using transplanted lichens: element concentrations across seasons.

    PubMed

    Malaspina, Paola; Tixi, Sara; Brunialti, Giorgio; Frati, Luisa; Paoli, Luca; Giordani, Paolo; Modenesi, Paolo; Loppi, Stefano

    2014-11-01

    We investigated the bioaccumulation of selected trace elements in samples of the lichen Evernia prunastri (L.) Ach. transplanted across two seasons in the urban area of Genoa (NW Italy), which is heavily affected by traffic and industrial pollution. Total concentration of most elements did not exhibit differences between seasons, exceptions being Al and Na, higher in summer, and As, Cd, and Ti, higher in winter. Differences emerged in the initial concentrations of some elements in control samples, and this was accounted for by the use of exposed-to-control (EC) ratios, which allowed interpretation of changes in element concentrations. The study area resulted highly polluted, likely by particulate matter, as suggested also by the higher concentrations of airborne PM10 during winter months. Bioaccumulation of particulate matter seems to be affected by differences in rainfall regimes across seasons, since element solubilization and leaching due to precipitation may vary considerably.

  6. THE CONTRIBUTION OF PARTICLE RESUSPENSION TO INDOOR AND PERSONAL AIR CONCENTRATIONS

    EPA Science Inventory

    An association has been demonstrated between ambient PM concentrations and human morbidity/mortality. However, little is known regarding the most important sources of PM exposure, inter- and intrapersonal variability in exposure, and the relationship between personal exposure a...

  7. Meteorological adjustment of yearly mean values for air pollutant concentration comparison

    NASA Technical Reports Server (NTRS)

    Sidik, S. M.; Neustadter, H. E.

    1976-01-01

    Using multiple linear regression analysis, models which estimate mean concentrations of Total Suspended Particulate (TSP), sulfur dioxide, and nitrogen dioxide as a function of several meteorologic variables, two rough economic indicators, and a simple trend in time are studied. Meteorologic data were obtained and do not include inversion heights. The goodness of fit of the estimated models is partially reflected by the squared coefficient of multiple correlation which indicates that, at the various sampling stations, the models accounted for about 23 to 47 percent of the total variance of the observed TSP concentrations. If the resulting model equations are used in place of simple overall means of the observed concentrations, there is about a 20 percent improvement in either: (1) predicting mean concentrations for specified meteorological conditions; or (2) adjusting successive yearly averages to allow for comparisons devoid of meteorological effects. An application to source identification is presented using regression coefficients of wind velocity predictor variables.

  8. Organic Nitrogen in Atmospheric Drops and Particles: Concentrations, (Limited) Speciation, and Chemical Transformations

    NASA Astrophysics Data System (ADS)

    Anastasio, C.; Zhang, Q.

    2003-12-01

    While quite a bit is known of the concentrations, speciation, and chemistry of inorganic forms of nitrogen in the atmosphere, the same cannot be said for organic forms. Despite this, there is growing evidence that organic N (ON) is ubiquitous in the atmosphere, especially in atmospheric condensed phases such as fog/cloud drops and aerosol particles. Although the major compounds that make up organic N are generally unknown, as are the sources of these compounds, it is clear that there are significant fluxes of ON between the atmosphere and ecosystems. It also appears that organic N can have significant effects in both spheres. The goal of our recent work in this area has been to better describe the atmospheric component of the biogeochemistry of organic nitrogen. Based on particle, gas, and fogwater samples from Northern California we have made three major findings: 1) Organic N represents a significant component, approximately 20%, of the total atmospheric N loading in these samples. This is broadly consistent with studies from other locations. 2) Amino compounds, primarily as combined amino acids, account for approximately 20% of the measured ON in our condensed phase samples. Given the properties of amino acids, these compounds could significantly affect the chemical and physical properties of atmospheric particles. 3) Organic nitrogen in atmospheric particles and drops is transformed to inorganic forms - primarily ammonium, nitrate, and nitrogen oxides (NOx) - during exposure to sunlight and/or ozone. These chemical reactions likely increase the bioavailability of the condensed phase nitrogen pool and enhance its biological effects after deposition to ecosystems.

  9. Effects of percentage of blockage and flameholder downstream counterbores on lean combustion limits of premixed, prevaporized propane-air mixture

    NASA Technical Reports Server (NTRS)

    Fernandez, M. A. B.

    1983-01-01

    Lean combustion limits were determined for a premixed prevaporized propane air mixture with flat plate flame stabilizers. Experiments were conducted in a constant area flame tube combustor utilizing flameholders of varying percentages of blockage and downstream counterbores. Combustor inlet air velocity at ambient conditions was varied from 4 to 9 meters per second. Flameholders with a center hole and four half holes surrounding it were tested with 63, 73, and 85 percent blockage and counterbore diameters of 112 and 125 percent of the thru hole diameter, in addition to the no counterbore configuration. Improved stability was obtained by using counterbore flameholders and higher percentages of blockage. Increases in mixture velocity caused the equivalence ratio at blowout to increase in all cases.

  10. A theoretical analysis of the extinction limits of a methane-air opposed-jet diffusion flame

    NASA Technical Reports Server (NTRS)

    Olson, S. L.; T'Ien, J. S.

    1987-01-01

    A theoretical analysis is described for a methane-air diffusion flame stabilized in the forward stagnation region of a porous metal cylinder in a forced convective flow. The analysis includes effects of radiative heat loss from the porous metal surface and finite rate kinetics but neglects the effects of gravity. The theoretically predicted extinction limits compare well with experimentally observed extinction limits from the literature. After the predicted limits compared well with the experimental limits, a parametric study of the effect of fuel surface emissivity and Lewis number was conducted with the numerical model. It was found that the computed blowoff limit is independent of radiative heat loss for high fuel blowing velocities but is a strong function of Lewis number. At low fuel blowing velocities, the extinction limit varies with both radiative heat loss and Lewis number. It is discovered, however, that even if thermal losses from the fuel surface are absent, the flame can extinguish at the fuel surface independently of Lewis number due to excessive reaction zone thinning.

  11. Temperature and food concentration have limited influence on the mixture toxicity of copper and Microcystis aeruginosa to Daphnia magna.

    PubMed

    Hochmuth, Jennifer D; Janssen, Colin R; De Schamphelaere, Karel A C

    2016-03-01

    Standard ecotoxicity tests are conducted under constant and favorable experimental conditions. In natural communities, however, the toxicity of chemicals may be influenced by abiotic and biotic environmental factors. Firstly, the authors examined the influence of temperature and total food concentration on the nature of the combined effects of copper (Cu) and the cyanobacterium Microcystis aeruginosa to Daphnia magna (i.e., whether the combined effects deviated from noninteraction). Secondly, the authors investigated the relative influence of the percentage of M. aeruginosa in the diet, temperature, and total food concentration on chronic Cu toxicity to D. magna. The nature of the combined effects between Cu and M. aeruginosa (i.e., synergism according to the independent action reference model and noninteraction according to concentration addition reference model) was not affected by temperature and total food concentration. In line with other studies, the concentration addition reference model gave rise to more protective predictions of mixture toxicity than the independent action reference model, thus confirming the former model's suitability as a conservative scenario for evaluating mixture toxicity of Cu and M. aeruginosa under the temperature and food concentrations tested. Further, the 21-d median effective concentration for Cu based on reproduction varied between 20 μg/L and 100 μg/L, and the results indicate that the percentage of M. aeruginosa explained 76% of the variance in the Cu median effective concentration for reproduction, whereas the effects of temperature and total food were limited (together explaining 11% of the variance). The present study suggests that environmental risk assessment of Cu should consider specific situations where harmful M. aeruginosa blooms can co-occur with elevated Cu exposure.

  12. Mapping Air Pollution Concentrations and Sources in China from Ground-Level Observations

    NASA Astrophysics Data System (ADS)

    Rohde, R. A.; Muller, R. A.

    2014-12-01

    China has recently established an extensive air quality monitoring system with over 1500 sites providing hourly data on airborne particulate matter (PM2.5 / PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), and carbon monoxide (CO). Based on Kriging interpolation of these surface data, we derive a detailed map of air pollution across the eastern half of China. In northern and central China, the pollution is widespread; contrary to popular belief, pollution is not simply localized to major cities such as Beijing, Shanghai, or Chongqing, or in geologic basins. Pollution levels are lower in southern China, in part due to frequent rains. By incorporating wind measurements and estimating pollution transport, we also infer source distributions for key pollutants. Sources are widespread, but many of the largest sources are often situated in or near major population centers. A northeast corridor extending from near Shanghai to north of Beijing includes many of the most significant pollution sources in China. Roughly 5% of the study region accounts for 25% of observed particulate matter emissions. During the analysis period, roughly half of the population of China was subjected to a long-term average pollution level in the unhealthy range, according to standards used by the US Environmental Protection Agency. In addition, nearly all of China's population (>90%) was exposed to unhealthy levels of air pollution at least some of the time. Based on health impact estimates from the Huai River Study, we estimate that the observed levels of particulate matter pollution contribute to about 1.4 million deaths every year in China, about 3500 per day, in agreement with prior estimates. Identification of sources from pollution data was facilitated by the reporting of hourly measurements, and we encourage other nations around the world to follow China's example and provide such time-resolved data.

  13. 40 CFR Table 3 to Subpart Kkkk of... - Emission Limits for Affected Sources Using the Control Efficiency/Outlet Concentration Compliance...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Using the Control Efficiency/Outlet Concentration Compliance Option 3 Table 3 to Subpart KKKK of Part 63... Concentration Compliance Option You must comply with the emission limits that apply to your affected source in... concentration option to comply with the emission limitations for any coating operation(s) . . . Then you...

  14. 40 CFR Table 3 to Subpart Kkkk of... - Emission Limits for Affected Sources Using the Control Efficiency/Outlet Concentration Compliance...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Using the Control Efficiency/Outlet Concentration Compliance Option 3 Table 3 to Subpart KKKK of Part 63... Concentration Compliance Option You must comply with the emission limits that apply to your affected source in... concentration option to comply with the emission limitations for any coating operation(s) . . . Then you...

  15. 40 CFR Table 3 to Subpart Kkkk of... - Emission Limits for Affected Sources Using the Control Efficiency/Outlet Concentration Compliance...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Using the Control Efficiency/Outlet Concentration Compliance Option 3 Table 3 to Subpart KKKK of Part 63... Concentration Compliance Option You must comply with the emission limits that apply to your affected source in... concentration option to comply with the emission limitations for any coating operation(s) . . . Then you...

  16. Effects of platinum stagnation surface on the lean extinction limits of premixed methane/air flames at moderate surface temperatures

    SciTech Connect

    Wiswall, J.T.; Li, J.; Wooldridge, M.S.; Im, H.G.

    2011-01-15

    A stagnation flow reactor was used to study the effects of platinum on the lean flammability limits of atmospheric pressure premixed methane/air flames at moderate stagnation surface temperatures. Experimental and computational methods were used to quantify the equivalence ratio at the lean extinction limit ({phi}{sub ext}) and the corresponding stagnation surface temperature (T{sub s}). A range of flow rates (57-90 cm/s) and corresponding strain rates were considered. The results indicate that the gas-phase methane/air flames are sufficiently strong relative to the heterogeneous chemistry for T{sub s} conditions less than 750 K that the platinum does not affect {phi}{sub ext}. The computational results are in good agreement with the experimentally observed trends and further indicate that higher reactant flow rates (>139 cm/s) and levels of dilution (>{proportional_to}10% N{sub 2}) are required to weaken the gas-phase flame sufficiently for surface reaction to play a positive role on extending the lean flammability limits. (author)

  17. Combustion rate limits of hydrogen plus hydrocarbon fuel: Air diffusion flames from an opposed jet burner technique

    NASA Technical Reports Server (NTRS)

    Pellett, Gerald L.; Guerra, Rosemary; Wilson, Lloyd G.; Reeves, Ronald N.; Northam, G. Burton

    1987-01-01

    Combustion of H2/hydrocarbon (HC) fuel mixtures may be considered in certain volume-limited supersonic airbreathing propulsion applications. Effects of HC addition to H2 were evaluated, using a recent argon-bathed, coaxial, tubular opposed jet burner (OJB) technique to measure the extinction limits of counterflow diffusion flames. The OJB flames were formed by a laminar jet of (N2 and/or HC)-diluted H2 mixture opposed by a similar jet of air at ambient conditions. The OJB data, derived from respective binary mixtures of H2 and methane, ethylene, or propane HCs, were used to characterize BLOWOFF and RESTORE. BLOWOFF is a sudden breaking of the dish-shaped OJB flame to a stable torus or ring shape, and RESTORE marks sudden restoration of the central flame by radial inward flame propagation. BLOWOFF is a measure of kinetically-limited flame reactivity/speed under highly stretched, but relatively ideal impingement flow conditions. RESTORE measures inward radial flame propagation rate, which is sensitive to ignition processes in the cool central core. It is concluded that relatively small molar amounts of added HC greatly reduce the reactivity characteristics of counterflow hydrogen-air diffusion flames, for ambient initial conditions.

  18. [Concentrations of mercury in ambient air in wastewater irrigated area of Tianjin City and its accumulation in leafy vegetables].

    PubMed

    Zheng, Shun-An; Han, Yun-Lei; Zheng, Xiang-Qun

    2014-11-01

    limit of mercury in food. Spinach appeared to accumulate more mercury than the other four vegetables, in which the median and mean mercury content were both higher than 20 μg x kg(-1). The mercury concentrations in rape, lettuce and allium tuberosum were lower than the standard. Moreover, test results indicated that the Hg content in leafy vegetables was mainly the gaseous mercury through leaf adsorption but not the Hg particulates. This study clearly manifested that there should be a great concern on the pollution risk of both air-and soil borne mercury when cultivating leafy vegetables in long-term wastewater-irrigated area.

  19. Air Pollution and Preterm Birth in the U.S. State of Georgia (2002–2006): Associations with Concentrations of 11 Ambient Air Pollutants Estimated by Combining Community Multiscale Air Quality Model (CMAQ) Simulations with Stationary Monitor Measurements

    PubMed Central

    Hao, Hua; Chang, Howard H.; Holmes, Heather A.; Mulholland, James A.; Klein, Mitch; Darrow, Lyndsey A.; Strickland, Matthew J.

    2015-01-01

    Background: Previous epidemiologic studies suggest associations between preterm birth and ambient air pollution. Objective: We investigated associations between 11 ambient air pollutants, estimated by combining Community Multiscale Air Quality model (CMAQ) simulations with measurements from stationary monitors, and risk of preterm birth (< 37 weeks of gestation) in the U.S. state of Georgia. Methods: Birth records for singleton births ≥ 27 weeks of gestation with complete covariate information and estimated dates of conception between 1 January 2002 and 28 February 2006 were obtained from the Office of Health Indicators for Planning, Georgia Department of Public Health (n = 511,658 births). Daily pollutant concentrations at 12-km resolution were estimated for 11 ambient air pollutants. We used logistic regression with county-level fixed effects to estimate associations between preterm birth and average pollutant concentrations during the first and second trimester. Discrete-time survival models were used to estimate third-trimester and total pregnancy associations. Effect modification was investigated by maternal education, race, census tract poverty level, and county-level urbanicity. Results: Trimester-specific and total pregnancy associations (p < 0.05) were observed for several pollutants. All the traffic-related pollutants (carbon monoxide, nitrogen dioxide, PM2.5 elemental carbon) were associated with preterm birth [e.g., odds ratios for interquartile range increases in carbon monoxide during the first, second, and third trimesters and total pregnancy were 1.005 (95% CI: 1.001, 1.009), 1.007 (95% CI: 1.002, 1.011), 1.010 (95% CI: 1.006, 1.014), and 1.011 (95% CI: 1.006, 1.017)]. Associations tended to be higher for mothers with low educational attainment and African American mothers. Conclusion: Several ambient air pollutants were associated with preterm birth; associations were observed in all exposure windows. Citation: Hao H, Chang HH, Holmes HA

  20. Inter-comparison of air pollutant concentrations in different indoor environments in Hong Kong

    NASA Astrophysics Data System (ADS)

    Lee, Shun-Cheng; Guo, Hai; Li, Wai-Ming; Chan, Lo-Yin

    Indoor air quality in selected indoor environments in Hong Kong such as homes, offices, schools, shopping malls and restaurants were investigated. Average CO 2 levels and total bacteria counts in air-conditioned classrooms, shopping malls and restaurants were comparatively higher than those measured in occupied offices and homes. Elevated CO 2 levels exceeding 1000 ppm and total bacteria counts resulted from high occupancy combined with inadequate ventilation. Average PM 10 levels were usually higher indoors than outdoors in homes, shopping malls and restaurants. The highest indoor PM 10 levels were observed at investigated restaurants due to the presence of cigarette smoking and extensive use of gas stoves for cooking. The restaurants and shopping malls investigated had higher formaldehyde levels than other indoor environments when building material, smoking and internal renovation work were present. Volatile organic compounds (VOCs) in both indoor and outdoor environments mainly resulted from vehicle exhaust emissions. It was observed that interior decoration work and the use of industrial solvents in an indoor environment could significantly increase the indoor levels of VOCs.