Science.gov

Sample records for air toxics modeling

  1. COMMUNITY SCALE AIR TOXICS MODELING WITH CMAQ

    EPA Science Inventory

    Consideration and movement for an urban air toxics control strategy is toward a community, exposure and risk-based modeling approach, with emphasis on assessments of areas that experience high air toxic concentration levels, the so-called "hot spots". This strategy will requir...

  2. AIR TOXICS MODELING RESEARCH PROGRAM: AN OVERVIEW

    EPA Science Inventory

    This product is a Microsoft Powerpoint slide presentation which was given at the joint EPA Region 3 - Mid-Atlantic Regional Air Management Association (MARAMA) Air Toxic Summit in Philadelphia, Pennsylvania held from October 18, 2005 through October 20, 2005. The slide presentat...

  3. 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...

  4. AIR QUALITY MODELING OF PM AND AIR TOXICS AT NEIGHBORHOOD SCALES

    EPA Science Inventory

    The current interest in fine particles and toxics pollutants provide an impetus for extending air quality modeling capability towards improving exposure modeling and assessments. Human exposure models require information on concentration derived from interpolation of observati...

  5. POPULATION EXPOSURE AND DOSE MODEL FOR AIR TOXICS: A BENZENE CASE STUDY

    EPA Science Inventory

    The EPA's National Exposure Research Laboratory (NERL) is developing a human exposure and dose model called the Stochastic Human Exposure and Dose Simulation model for Air Toxics (SHEDS-AirToxics) to characterize population exposure to air toxics in support of the National Air ...

  6. Validation of a novel air toxic risk model with air monitoring.

    PubMed

    Pratt, Gregory C; Dymond, Mary; Ellickson, Kristie; Thé, Jesse

    2012-01-01

    Three modeling systems were used to estimate human health risks from air pollution: two versions of MNRiskS (for Minnesota Risk Screening), and the USEPA National Air Toxics Assessment (NATA). MNRiskS is a unique cumulative risk modeling system used to assess risks from multiple air toxics, sources, and pathways on a local to a state-wide scale. In addition, ambient outdoor air monitoring data were available for estimation of risks and comparison with the modeled estimates of air concentrations. Highest air concentrations and estimated risks were generally found in the Minneapolis-St. Paul metropolitan area and lowest risks in undeveloped rural areas. Emissions from mobile and area (nonpoint) sources created greater estimated risks than emissions from point sources. Highest cancer risks were via ingestion pathway exposures to dioxins and related compounds. Diesel particles, acrolein, and formaldehyde created the highest estimated inhalation health impacts. Model-estimated air concentrations were generally highest for NATA and lowest for the AERMOD version of MNRiskS. This validation study showed reasonable agreement between available measurements and model predictions, although results varied among pollutants, and predictions were often lower than measurements. The results increased confidence in identifying pollutants, pathways, geographic areas, sources, and receptors of potential concern, and thus provide a basis for informing pollution reduction strategies and focusing efforts on specific pollutants (diesel particles, acrolein, and formaldehyde), geographic areas (urban centers), and source categories (nonpoint sources). The results heighten concerns about risks from food chain exposures to dioxins and PAHs. Risk estimates were sensitive to variations in methodologies for treating emissions, dispersion, deposition, exposure, and toxicity.

  7. Air quality modeling of selected aromatic and non-aromatic air toxics in the Houston urban and industrial airshed

    NASA Astrophysics Data System (ADS)

    Coarfa, Violeta Florentina

    2007-12-01

    Air toxics, also called hazardous air pollutants (HAPs), pose a serious threat to human health and the environment. Their study is important in the Houston area, where point sources, mostly located along the Ship Channel, mobile and area sources contribute to large emissions of such toxic pollutants. Previous studies carried out in this area found dangerous levels of different HAPs in the atmosphere. This thesis presents several studies that were performed for the aromatic and non-aromatic air toxics in the HGA. For these studies we developed several tools: (1) a refined chemical mechanism, which explicitly represents 18 aromatic air toxics that were lumped under two model species by the previous version, based on their reactivity with the hydroxyl radical; (2) an engineering version of an existing air toxics photochemical model that enables us to perform much faster long-term simulations compared to the original model, that leads to a 8--9 times improvement in the running time across different computing platforms; (3) a combined emission inventory based on the available emission databases. Using the developed tools, we quantified the mobile source impact on a few selected air toxics, and analyzed the temporal and spatial variation of selected aromatic and non-aromatic air toxics in a few regions within the Houston area; these regions were characterized by different emissions and environmental conditions.

  8. CMAQ MODELING FOR AIR TOXICS AT FINE SCALES: A PROTOTYPE STUDY

    EPA Science Inventory

    Toxic air pollutants (TAPs) or hazardous air pollutants (HAPs) exhibit considerable spatial and temporal variability across urban areas. Therefore, the ability of chemical transport models (CTMs), e.g. Community Multi-scale Air Quality (CMAQ), to reproduce the spatial and tempor...

  9. APPLICATION OF FINE SCALE AIR TOXICS MODELING WITH CMAQ TO HAPEM5

    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 Multiscale Air Quality (CMAQ) modeling system to the fifth version of the Hazardous Pollutant Exposure Model (HAPEM5). For t...

  10. National Air Toxics Assessment

    EPA Pesticide Factsheets

    NATA is an ongoing comprehensive evaluation of air toxics in the U.S. As a screening tool, it helps air agencies prioritize pollutants, emission sources and locations of interest for further study to gain a better understanding of risks.

  11. Other Priority Air Toxics in New England | Air Toxics | New ...

    EPA Pesticide Factsheets

    2017-04-10

    The air toxics of greatest concern in New England were selected due to risk modeling for only the inhalation route of exposure and these pollutants exceeded the health benchmarks in one or more of the New England states.

  12. 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...

  13. Comparing toxic air pollutant programs

    SciTech Connect

    Hawkins, S.C.

    1997-05-01

    This article compares state and federal toxic air pollutant programs. The Clean Air Act Ammendments created a program for the control of Hazardous Air Pollutants based on the establishment of control technology standards. State toxic programs can be classified into two categories: control technology-based and ambient concentration-based. Many states have opened to implement the MACT standards while enforcing their own state air toxics programs. Specific topics discussed include the following: the Federal air toxics program; existing state regulations; New Jersey Air Toxic Program; New York Toxics program.

  14. 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 ...

  15. FURTHER REFINEMENTS AND TESTING OF APEX3.0: EPA'S POPULATION EXPOSURE MODEL FOR CRITERIA AND AIR TOXIC INHALATION

    EPA Science Inventory

    The Air Pollutants Exposure Model (APEX(3.0)) is a PC-based model that was derived from the probabilistic NAAQS Exposure Model for carbon monoxide (pNEM/CO). APEX will be one of the tools used to estimate human population exposure for criteria and air toxic pollutants as part ...

  16. NATIONAL-SCALE ASSESSMENT OF AIR TOXICS RISKS

    EPA Science Inventory

    The national-scale assessment of air toxics risks is a modeling assessment which combines emission inventory development, atmospheric fate and transport modeling, exposure modeling, and risk assessment to characterize the risk associated with inhaling air toxics from outdoor sour...

  17. RESOLVING NEIGHBORHOOD-SCALE AIR TOXICS MODELING: A CASE STUDY IN WILMINGTON, CALIFORNIA

    EPA Science Inventory

    Air quality modeling is useful for characterizing exposures to air pollutants. While models typically provide results on regional scales, there is a need for refined modeling approaches capable of resolving concentrations on the scale of tens of meters, across modeling domains 1...

  18. Model-predicted concentrations of toxic air pollutants in the Minneapolis/St. Paul Metropolitan Area

    SciTech Connect

    McCourtney, M.; Pratt, G.; Wu, C.Y.

    1998-12-31

    The availability of sophisticated emission inventory methods, air dispersion models and personal computers has opened the door to developing more comprehensive studies of air concentrations of various pollutants. As part of a grant from the US Environmental Protection Agency, a current emission inventory and the Industrial Source Complex short-term dispersion model, version 3 (ISCST3) were used to estimate the ambient concentrations of several toxic compounds throughout the Minneapolis/St. Paul Metropolitan Area. A detailed emission inventory was developed of point, area and mobile sources in seven contiguous metropolitan counties that account for approximately half the population of Minnesota. Of specific interest were those sources that emit at least one of the eight Volatile Organic Compounds (VOCs): benzene, 1,3-butadiene, carbon tetrachloride, chloroform, methyl chloride, styrene, tetrachloroethylene and toluene. Emission rates were calculated for 69 industrial point sources; mobile sources, including on-road vehicles and non-road vehicles (such as aircraft, locomotives, commercial marine, agricultural, recreational, and lawn and garden equipment); and area sources, which consisted of dry cleaners, architectural surface coatings, commercial/consumer solvent products, residential fossil fuel combustion, automobile refinishing, residential wood burning, public-owned treatment works, landfills and gas stations. The ISCST3 model was used to estimate the 24-hour and annual average concentrations of the selected pollutants throughout the Minneapolis/St. Paul Metropolitan Area. Three sets of receptors were developed: a fine receptor grid with 500 meter spacing in the urban core, a coarse receptor grid with 5000 meter spacing covering the metropolitan area, and discrete receptors located 100 meters in each of four directions around each point source.

  19. Air toxics issues in the 1990s

    SciTech Connect

    Not Available

    1991-01-01

    This book on air toxic issues is organized under the following headings: initiatives by state and local regulatory agencies; industry's role in meeting air toxics goals of the reauthorized Clean Air Act; implementation of strategies and public health impacts; regulatory, permitting, and enforcement strategies; air toxics control; emission estimation, impact analysis and monitoring.

  20. Criteria air pollutants and toxic air pollutants.

    PubMed Central

    Suh, H H; Bahadori, T; Vallarino, J; Spengler, J D

    2000-01-01

    This review presents a brief overview of the health effects and exposures of two criteria pollutants--ozone and particulate matter--and two toxic air pollutants--benzene and formaldehyde. These pollutants were selected from the six criteria pollutants and from the 189 toxic air pollutants on the basis of their prevalence in the United States, their physicochemical behavior, and the magnitude of their potential health threat. The health effects data included in this review primarily include results from epidemiologic studies; however, some findings from animal studies are also discussed when no other information is available. Health effects findings for each pollutant are related in this review to corresponding information about outdoor, indoor, and personal exposures and pollutant sources. Images Figure 3 Figure 8 Figure 9 PMID:10940240

  1. Air Toxics in New England | US EPA

    EPA Pesticide Factsheets

    2017-04-10

    Find general information about air toxics, what EPA is doing to reduce ambient air toxics levels, information on the reductions we have seen to date from large New England manufacturing companies, as well as links to other related websites.

  2. 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...

  3. Measurement and modeling of exposure to selected air toxics for health effects studies and verification by biomarkers.

    PubMed

    Harrison, Roy M; Delgado-Saborit, Juana Maria; Baker, Stephen J; Aquilina, Noel; Meddings, Claire; Harrad, Stuart; Matthews, Ian; Vardoulakis, Sotiris; Anderson, H Ross

    2009-06-01

    The overall aim of our investigation was to quantify the magnitude and range of individual personal exposures to a variety of air toxics and to develop models for exposure prediction on the basis of time-activity diaries. The specific research goals were (1) to use personal monitoring of non-smokers at a range of residential locations and exposures to non-traffic sources to assess daily exposures to a range of air toxics, especially volatile organic compounds (VOCs) including 1,3-butadiene and particulate polycyclic aromatic hydrocarbons (PAHs); (2) to determine microenvironmental concentrations of the same air toxics, taking account of spatial and temporal variations and hot spots; (3) to optimize a model of personal exposure using microenvironmental concentration data and time-activity diaries and to compare modeled exposures with exposures independently estimated from personal monitoring data; (4) to determine the relationships of urinary biomarkers with the environmental exposures to the corresponding air toxic. Personal exposure measurements were made using an actively pumped personal sampler enclosed in a briefcase. Five 24-hour integrated personal samples were collected from 100 volunteers with a range of exposure patterns for analysis of VOCs and 1,3-butadiene concentrations of ambient air. One 24-hour integrated PAH personal exposure sample was collected by each subject concurrently with 24 hours of the personal sampling for VOCs. During the period when personal exposures were being measured, workplace and home concentrations of the same air toxics were being measured simultaneously, as were seasonal levels in other microenvironments that the subjects visit during their daily activities, including street microenvironments, transport microenvironments, indoor environments, and other home environments. Information about subjects' lifestyles and daily activities were recorded by means of questionnaires and activity diaries. VOCs were collected in tubes packed

  4. NEIGHBORHOOD SCALE MODELING OF PM 2.5 AND AIR TOXICS CONCENTRATION DISTRIBUTIONS TO DRIVE HUMAN EXPOSURE MODELS

    EPA Science Inventory

    Air quality (AQ) simulation models provide a basis for implementing the National Ambient Air Quality Standards (NAAQS) and are a tool for performing risk-based assessments and for developing environmental management strategies. Fine particulate matter (PM 2.5), its constituent...

  5. 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...

  6. Assessing the influence of traffic-related air pollution on risk of term low birth weight on the basis of land-use-based regression models and measures of air toxics.

    PubMed

    Ghosh, Jo Kay C; Wilhelm, Michelle; Su, Jason; Goldberg, Daniel; Cockburn, Myles; Jerrett, Michael; Ritz, Beate

    2012-06-15

    Few studies have examined associations of birth outcomes with toxic air pollutants (air toxics) in traffic exhaust. This study included 8,181 term low birth weight (LBW) children and 370,922 term normal-weight children born between January 1, 1995, and December 31, 2006, to women residing within 5 miles (8 km) of an air toxics monitoring station in Los Angeles County, California. Additionally, land-use-based regression (LUR)-modeled estimates of levels of nitric oxide, nitrogen dioxide, and nitrogen oxides were used to assess the influence of small-area variations in traffic pollution. The authors examined associations with term LBW (≥37 weeks' completed gestation and birth weight <2,500 g) using logistic regression adjusted for maternal age, race/ethnicity, education, parity, infant gestational age, and gestational age squared. Odds of term LBW increased 2%-5% (95% confidence intervals ranged from 1.00 to 1.09) per interquartile-range increase in LUR-modeled estimates and monitoring-based air toxics exposure estimates in the entire pregnancy, the third trimester, and the last month of pregnancy. Models stratified by monitoring station (to investigate air toxics associations based solely on temporal variations) resulted in 2%-5% increased odds per interquartile-range increase in third-trimester benzene, toluene, ethyl benzene, and xylene exposures, with some confidence intervals containing the null value. This analysis highlights the importance of both spatial and temporal contributions to air pollution in epidemiologic birth outcome studies.

  7. Final Recommendations of the Air Toxics Work Group

    EPA Pesticide Factsheets

    The Air Toxics Workgroup was organized under the Clean Air Act Advisory Committee for the purpose of discussing and identifying recommendations related to Urban Air Toxics. The workgroup is part of the Permits, New Source Review and Toxics Subcommittee.

  8. Chemical air pollutants and otorhinolaryngeal toxicity

    SciTech Connect

    Bisesi, M.S.; Rubin, A.M. . Occupational Health and Otolaryngology)

    1994-03-01

    Air pollution and the specific issue regarding the impact of airborne chemical agents to human health are familiar topics to most members of the environmental health science and environmental medicine communities. Some aspects, however, have received relatively less attention. Much has been published regarding the impact of air pollutants on the human upper and lower respiratory system, including interaction with the rhinologic (nasal) system. Relatively fewer data have been published, however, regarding the potential impact of air pollutants in reference specifically to the otologic (auditory and vestibular) and the laryngeal (larynx) system. Adverse impact to the ears, nose and throat, referred to as the otorhinolaryngeal system'', warrants attention as an important environmental health issue. Toxic interactions from exposure to many chemical air pollutants not only causes potential respiratory irritation and lung disease, but can also result in impaired hearing, balance, sense of smell, taste, and speech due to interaction with related target systems. This may be significant to environmental health risk assessment of chemical air pollutants if multi-target site models are considered.

  9. Community Multiscale Air Quality Modeling System (CMAQ)

    EPA Pesticide Factsheets

    CMAQ is a computational tool used for air quality management. It models air pollutants including ozone, particulate matter and other air toxics to help determine optimum air quality management scenarios.

  10. Air Toxics of Greatest Concern in New England | Air Toxics in ...

    EPA Pesticide Factsheets

    2017-04-10

    The 2011 National Air Toxics Assessment (NATA) estimated that state average risk values of five air toxics: acetaldehyde, benzene, carbon tetrachloride, formaldehyde, and polycyclic organic matter (POM) exceeded health benchmarks in every state in New England, and state average risk values of five air toxics: 1, 3-butadiene, acrolein, arsenic compounds, chromium compounds and naphthalene exceeded health benchmarks in at least one state in New England.

  11. CAirTOX: A compartment model for assessing the fate of and human exposure to toxic-chemical emissions to air

    SciTech Connect

    McKone, T.E.

    1993-10-01

    CAirTOX has been developed as a spreadsheet model to assist in making a risk assessment of toxic air emissions. With CAirTOX, one can address how contaminants released to an air basin can lead to contamination of soil, food, surface water, and sediments. The modeling effort includes a multimedia transport and transformation model, exposure scenario models, and efforts to quantify uncertainty in multimedia, multiple-pathway exposure assessments. The multimedia transport and transformation model is a steady-state, but non-equilibrium model that can be used to assess concentrations of contaminants released continuously to air. In Part 1, the authors describe the multimedia transport and transformation model used to determine the fate of air emissions. In Part 2, they describe inputs and data needs for CAirTOX and the development of a set of landscape factors, which can be used to represent regional air basin/water-shed systems in California. In Part 3, they describe the multiple-pathway exposure scenarios and exposure algorithms. In Part 4, they compare the HRA approach and results and the CAirTOX exposure equations. In Part 5, they consider model sensitivity and uncertainty to determine how variability and uncertainty in model inputs affects the precision, accuracy, and credibility of the model output.

  12. Mobile source contributions to U.S. air toxics

    SciTech Connect

    Paul, R.T.; Pezda, S.A.

    1997-12-31

    On-road motor vehicle emissions include several components which are considered hazardous air pollutants (HAPs) under Title III, section 112, of the Clean Air Act. Although section 112 focuses on stationary sources of HAPs, it is important to evaluate all potentially significant sources of HAPs to urban air. This paper will utilize the most recent data available on emission factors, tail-pipe analysis, fuel specifications, dispersion modeling and other information to characterize on-road mobile source contributions to urban air toxics. In particular, benzene, 1,3-butadiene and formaldehyde emissions will be evaluated. Estimates of exposure to urban populations will also be made based on emission levels, dispersion modeling and ambient concentrations, including limitations and uncertainties. A perspective will also be provided with respect to vehicle air toxic emissions and indoor versus outdoor exposures.

  13. Air toxics regulatory issues facing urban settings

    SciTech Connect

    Olden, K.; Guthrie, J.

    1996-10-01

    Biomarker research does not exist in isolation. Its usefulness can only be realized when it is translated into prevention strategies to protect public health. In the context of air toxics, these prevention strategies begin with the development of regulatory standards derived from risk assessment schemes. The Clean Air Act Amendments of 1990 list 189 air toxics, including many volatile organics, metals, and pesticides. The National Institute of Environmental Health Sciences (NIEHS), through its affiliation with the National Toxicology Program, has generated toxicity and carcinogenicity data on more than 100 of these air toxics. The NIEHS extramural and intramural research portfolios support a variety of projects that develop and validate biomarkers for use in environmental health science and risk assessment. Biomarkers have a tremendous potential in the areas of regulating air toxics and protecting public health. Risk assessors need data provided by biomarkers of exposure, biomarkers of close/pharmacokinetics, biomarkers of susceptibility or individual variability, and biomarkers of effects. The greatest benefit would be realized if biomarkers could be employed in four areas of primary and secondary prevention. The first is the use of biomarkers to enhance extrapolation of animal data to human exposure situations in establishing risk standards. The second is the use of biomarkers that assess noncancer, as well as cancer, end points. Important health end points include pulmonary dysfunction, immunotoxicity, and neurotoxicity. Third, biomarkers that serve as early warning signs to detect intermediate effects would enhance our ability to design timely and cost-effective intervention strategies. Finally, biomarkers used to evaluate the effectiveness of intervention strategies both in clinical and regulatory settings, would enable us to ensure that programs designed to protect public health do, in fact, achieve the desired outcome. 9 refs., 2 tabs.

  14. Community Multi-scale Air Quality (CMAQ) Modeling System for Air Quality Management

    EPA Pesticide Factsheets

    CMAQ simultaneously models multiple air pollutants including ozone, particulate matter and a variety of air toxics to help air quality managers determine the best air quality management scenarios for their communities, regions and states.

  15. Component modeling in ecological risk assessment: Disturbance in interspecific interactions caused by air toxics introduced into terrestrial ecosystems

    NASA Astrophysics Data System (ADS)

    Swider, Jan Zenon

    Ecological Risk Assessment standpoint and examine the impact of air toxics emissions on an ecosystem, with particular emphasis on predator-prey interactions. Such analysis may help to identify the most likely conditions leading to the ecosystem instability and possibility of its recuperation.

  16. The Air Toxics Health Effects Database (ATHED).

    PubMed

    Woodall, George M; Smith, Roy L

    2008-11-15

    The Air Toxics Health Effects Database (ATHED) is currently used by the EPA's Office of Air Quality Planning and Standards (OAQPS) to support risk assessments for the Residual Risk Program. An assessment of the residual risk is required to be performed at a specified time (typically 8 years) following the promulgation of a technology-based Maximum Achievable Control Technologies (MACT) standard. The goal of the Residual Risk Program is to assure that the risk that remains after MACT standards are implemented (i.e., the "residual risk") is acceptable, and if not, to propose additional regulations to mitigate those risks. ATHED maintains all available reference values for each chemical as separate data records, and includes values for all exposure durations (acute, short-term, subchronic and chronic). These values are used as benchmarks to determine acceptable exposure levels to the hazardous air pollutants (HAPs) listed in Section 112 of the Clean Air Act. ATHED also provides useful background information on the uncertainty and/or modifying factors that were applied in the derivation of each reference value, as well as the point of departure and the critical study/studies. To facilitate comparisons across durations for a specific chemical, ATHED data can be graphically presented.

  17. EMISSIONS OF ORGANIC AIR TOXICS FROM OPEN ...

    EPA Pesticide Factsheets

    A detailed literature search was performed to collect and collate available data reporting emissions of toxic organic substances into the air from open burning sources. Availability of data varied according to the source and the class of air toxics of interest. Volatile organic compound (VOC) and polycyclic aromatic hydrocarbon (PAH) data were available for many of the sources. Data on semivolatile organic compounds (SVOCs) that are not PAHs were available for several sources. Carbonyl and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofuran (PCDD/F) data were available for only a few sources. There were several sources for which no emissions data were available at all. Several observations were made including: 1) Biomass open burning sources typically emitted less VOCs than open burning sources with anthropogenic fuels on a mass emitted per mass burned basis, particularly those where polymers were concerned; 2) Biomass open burning sources typically emitted less SVOCs and PAHs than anthropogenic sources on a mass emitted per mass burned basis. Burning pools of crude oil and diesel fuel produced significant amounts of PAHs relative to other types of open burning. PAH emissions were highest when combustion of polymers was taking place; and 3) Based on very limited data, biomass open burning sources typically produced higher levels of carbonyls than anthropogenic sources on a mass emitted per mass burned basis, probably due to oxygenated structures r

  18. Basic Information about Mercury and Air Toxics Standards

    EPA Pesticide Factsheets

    The U.S. Environmental Protection Agency (EPA) has proposed Mercury and Air Toxics Standards (MATS) for power plants to limit mercury, acid gases and other toxic pollution from power plants. This page describes how federal mercury standards work.

  19. 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 ...

  20. Risk Assessment for Toxic Air Pollutants: A Citizen's Guide

    MedlinePlus

    ... IT ALL UP Public health agencies concerned with air quality perform risk assessments to determine the increased risk of illness from a specific human exposure to a toxic air pollutant. Risk assessment is a four-step process: ( ...

  1. Controlling air toxics through advanced coal preparation

    SciTech Connect

    Straszheim, W.E.; Buttermore, W.H.; Pollard, J.L.

    1995-11-01

    This project involves the assessment of advanced coal preparation methods for removing trace elements from coal to reduce the potential for air toxic emissions upon combustion. Scanning electron microscopy-based automated image analysis (SEM-AIA) and advanced washability analyses are being applied with state-of-the-art analytical procedures to predict the removal of elements of concern by advanced column flotation and to confirm the effectiveness of preparation on the quality of quantity of clean coal produced. Specific objectives are to maintain an acceptable recovery of combustible product, while improving the rejection of mineral-associated trace elements. Current work has focused on determining conditions for controlling column flotation system across its operating range and on selection and analysis of samples for determining trace element cleanability.

  2. EMISSIONS OF ORGANIC AIR TOXICS FROM OPEN BURNING

    EPA Science Inventory

    A detailed literature search was performed to collect and collate available data reporting emissions of toxic organic substances into the air from open burning sources. Availability of data varied according to the source and the class of air toxics of interest. Volatile organic c...

  3. Assessing exposure to air toxics relative to asthma.

    PubMed

    Weisel, Clifford P

    2002-08-01

    Asthma is a respiratory disease whose prevalence has been increasing since the mid 1970s and that affects more than 14.6 million residents of the United States. Environmental triggers of asthma include air pollutants that are respiratory irritants. Air toxics emitted into the ambient air are listed in the 1990 Clean Air Act Amendments as hazardous air pollutants (HAPs) if they can adversely affect human health, including the respiratory tract. HAPs include particulate and gaseous-phase pollutants, individual organic compounds and metals, and mixtures. Associations between asthma exacerbation and both particles and indoor volatile organic compounds (VOCs), often referred to as indoor air quality, have been reported. Studies conducted in the United States, Canada, and Europe over the past two decades have shown that most people living in the developed countries spend the majority of their time indoors and that the air concentrations of many air toxics or HAPs are higher indoors than in the ambient air in urban, suburban, and rural settings. Elevated indoor air concentrations result from emissions of air toxics from consumer products, household furnishings, and personal activities. The Relationship of Indoor, Outdoor and Personal Air (RIOPA) study was designed to oversample homes in close proximity to ambient sources, excluding residences where smokers lived, to determine the contribution of ambient emissions to air toxics exposure. The ratios of indoor to outdoor air concentrations of some VOCs in homes measured during RIOPA were much greater than one, and for most other VOCs that had indoor-to-outdoor ratios close to unity in the majority of homes, elevated ratios were found in the paired samples with the highest concentration. Thus, although ambient emissions contribute to exposure of some air toxics indoors as well as outdoors, this was not true for all of the air toxics and especially for the higher end of exposures to most volatile organic air toxics examined

  4. Inhalation exposure and risk from mobile source air toxics in future years.

    PubMed

    Cook, Richard; Strum, Madeleine; Touma, Jawad S; Palma, Ted; Thurman, James; Ensley, Darrell; Smith, Roy

    2007-01-01

    Modeling of inhalation exposure and risks resulting from exposure to mobile source air toxics can be used to evaluate impacts of reductions from control programs on overall risk, as well as changes in relative contributions of different source sectors to risk, changes in contributions of different pollutants to overall risk, and changes in geographic distributions of risk. Such analysis is useful in setting regulatory priorities, and informing the decision-making process. In this paper, we have conducted national-scale air quality, exposure, and risk modeling for the US in the years 2015, 2020, and 2030, using similar tools and methods as the 1999 National-Scale Air Toxics Assessment. Our results suggest that US Environmental Protection Agency emission control programs will substantially reduce average inhalation cancer risks and potential noncancer health risks from exposure to mobile source air toxics. However, cancer risk and noncancer hazard due to inhalation of air toxics will continue to be a public health concern.

  5. QUANTIFYING SUBGRID POLLUTANT VARIABILITY IN EULERIAN AIR QUALITY MODELS

    EPA Science Inventory

    In order to properly assess human risk due to exposure to hazardous air pollutants or air toxics, detailed information is needed on the location and magnitude of ambient air toxic concentrations. Regional scale Eulerian air quality models are typically limited to relatively coar...

  6. Community-Scale Air Toxics Ambient Monitoring Grant - Closed Announcement FY 2015

    EPA Pesticide Factsheets

    Grant to fund projects designed to assist state, local and tribal communities in identifying air toxics sources, characterizing the degree and extent of local-scale air toxics problems, tracking progress of air toxics reduction activities, etc.

  7. INEEL AIR MODELING PROTOCOL ext

    SciTech Connect

    C. S. Staley; M. L. Abbott; P. D. Ritter

    2004-12-01

    Various laws stemming from the Clean Air Act of 1970 and the Clean Air Act amendments of 1990 require air emissions modeling. Modeling is used to ensure that air emissions from new projects and from modifications to existing facilities do not exceed certain standards. For radionuclides, any new airborne release must be modeled to show that downwind receptors do not receive exposures exceeding the dose limits and to determine the requirements for emissions monitoring. For criteria and toxic pollutants, emissions usually must first exceed threshold values before modeling of downwind concentrations is required. This document was prepared to provide guidance for performing environmental compliance-driven air modeling of emissions from Idaho National Engineering and Environmental Laboratory facilities. This document assumes that the user has experience in air modeling and dose and risk assessment. It is not intended to be a "cookbook," nor should all recommendations herein be construed as requirements. However, there are certain procedures that are required by law, and these are pointed out. It is also important to understand that air emissions modeling is a constantly evolving process. This document should, therefore, be reviewed periodically and revised as needed. The document is divided into two parts. Part A is the protocol for radiological assessments, and Part B is for nonradiological assessments. This document is an update of and supersedes document INEEL/INT-98-00236, Rev. 0, INEEL Air Modeling Protocol. This updated document incorporates changes in some of the rules, procedures, and air modeling codes that have occurred since the protocol was first published in 1998.

  8. A framework for assessing the impact of land use policy on community exposure to air toxics.

    PubMed

    Willis, Melvin R; Keller, Arturo A

    2007-04-01

    Our research focuses on the linkage between land use planning policy and the spatial pattern of exposure to air toxics emissions. Our objective is to develop a modeling framework for assessment of the community health risk implications of land use policy. The modeling framework is not intended to be a regulatory tool for small-scale land use decisions, but a long-range planning tool to assess the community health risk implications of alternative land use scenarios at a regional or subregional scale. This paper describes the development and application of an air toxic source model for generating aggregate emission factors for industrial and commercial zoning districts as a function of permitted uses. To address the uncertainty of estimating air toxics emission rates for planned general land use or zoning districts, the source model uses an emissions probability mass function that weights each incremental permitted land use activity by the likelihood of occurrence. We thus reduce the uncertainty involved in planning for development with no prior knowledge of the specific industries that may locate within the land use district. These air toxics emission factors can then be used to estimate pollutant atmospheric mass flux from land use zoning districts, which can then be input to air dispersion and human health risk assessment models to simulate the spatial pattern of air toxics exposure risk. The model database was constructed using the California Air Toxics Inventory, 1997 US Economic Census, and land assessment records from several California counties. The database contains information on more than 200 air toxics at the 2-digit Standard Industrial Classification (SIC) level. We present a case study to illustrate application of the model. LUAIRTOX, the interactive spreadsheet model that applies our methodology to the California data, is available at http://www2.bren.ucsb.edu/~mwillis/LUAIRTOX.htm.

  9. Air toxics and asthma: Impacts and end points

    SciTech Connect

    Eschenbacher, W.L.; Holian, A.; Campion, R.J.

    1995-09-01

    The National Urban Air Toxics Research Center (NUATRC) hosted a medical/scientific workshop (February 1994) focused on possible asthma/air toxics relationships, with the results of the NUATRC`s first research contract with the University of Cincinnati as the point of discussion. The workshop explored the impact of various environmental factors, including air toxics, on asthma incidence and exacerbation; and emphasis was placed on future research directions. The information presented at the workshop suggested a possible association of asthma exacerbations with ozone and particulate matter (PM{sub 10}); however, direct relationships between worsening asthma and air toxic ambient levels were not established. Possible respiratory health effects associated with air toxics will require considerably more investigation, especially in the area of human exposure assessment. Two major recommendations for future research resulted form this workshop and an accompanying NUATRC Scientific Advisory Panel meeting: a need for more complete individual personal exposure assessments so that accurate determinations of actual personal exposures to various pollutants can be made; and a need for field experiments utilizing biomarkers of exposure and effect to more accurately assess the extent and variability of the biological effects, if any, of individual air toxics. 8 refs.

  10. Modelling Hot Air Balloons.

    ERIC Educational Resources Information Center

    Brimicombe, M. W.

    1991-01-01

    A macroscopic way of modeling hot air balloons using a Newtonian approach is presented. Misleading examples using a car tire and the concept of hot air rising are discussed. Pressure gradient changes in the atmosphere are used to explain how hot air balloons work. (KR)

  11. Evolution of the Air Toxics under the Big Sky Program

    ERIC Educational Resources Information Center

    Marra, Nancy; Vanek, Diana; Hester, Carolyn; Holian, Andrij; Ward, Tony; Adams, Earle; Knuth, Randy

    2011-01-01

    As a yearlong exploration of air quality and its relation to respiratory health, the "Air Toxics Under the Big Sky" program offers opportunities for students to learn and apply science process skills through self-designed inquiry-based research projects conducted within their communities. The program follows a systematic scope and sequence…

  12. The National Near-Road Mobile Source Air Toxics Study

    EPA Science Inventory

    Recently, much attention has been directed at understanding the impact of mobile sources on near-road air quality, especially PM and its components, NOx and CO, but little information exists for mobile source air toxics (MSATs). MSATs of interest to this project are 1,3-butadiene...

  13. Air toxics and asthma: impacts and end points.

    PubMed

    Eschenbacher, W L; Holian, A; Campion, R J

    1995-09-01

    The National Urban Air Toxics Research Center (NUATRC) hosted a medical/scientific workshop focused on possible asthma/air toxics relationships, with the results of the NUATRC's first research contract with the University of Cincinnati as the point of discussion. The workshop was held at the Texas Medical Center on 4 February 1994 and featured presentations by distinguished academic, government, and industry scientists. This one-day session explored the impact of various environmental factors, including air toxics, on asthma incidence and exacerbation; an emphasis was placed on future research directions to be pursued in the asthma/air toxics area. A key research presentation on the association of air toxics and asthma, based on the study sponsored by NUATRC, was given by Dr. George Leikauf of the University of Cincinnati Medical Center. Additional presentations were made by H. A. Boushey, Jr., Cardiovascular Research Institute/University of California at San Francisco, who spoke on of the Basic Mechanisms of Asthma; K. Sexton, U.S. Environmental Protection Agency, who spoke on hazardous air pollutants: science/policy interface; and D. V. Bates, Department of Health Care and Epidemiology at the University of British Columbia, who spoke on asthma epidemiology. H. Koren, U.S. Environmental Protection Agency, and M. Yeung, of the Respiratory Division/University of British Columbia, Vancouver General Hospital, discussed occupational health impacts on asthma. Doyle Pendleton, Texas Natural Resource Conservation Commission, reviewed air quality measurements in Texas. The information presented at the workshop suggested a possible association of asthma exacerbations with ozone and particulate matter (PM10); however, direct relationships between worsening asthma and air toxic ambient levels were not established. Possible respiratory health effects associated with air toxics will require considerably more investigation, especially in the area of human exposure assessment

  14. SNRB{trademark} air toxics monitoring. Final report

    SciTech Connect

    Not Available

    1994-01-01

    Babcock & Wilcox (B&W) is currently conducting a project under the DOE`s Clean Coal Technology (CCT II) Program to demonstrate its SO{sub x}NO{sub x}-Rox Box{trademark} (SNRB{trademark}) process in a 5 MWe Field Demonstration Unit at Ohio Edison`s R. E. Burger Plant near Shadyside, Ohio. The objective of the SNRB{trademark} Air Toxics Monitoring Project was to provide data on SNRB{trademark} air toxics emissions control performance to B&W and to add to the DOE/EPRI/EPA data base by quantifying the flow rates of selected hazardous substances (or air toxics) in all of the major input and output streams of the SNRB{trademark} process as well as the power plant. Work under the project included the collection and analysis of representative samples of all major input and output streams of the SNRB{trademark} demonstration unit and the power plant, and the subsequent laboratory analysis of these samples to determine the partitioning of the hazardous substances between the various process streams. Material balances for selected air toxics were subsequently calculated around the SNRB{trademark} and host boiler systems, including the removal efficiencies across each of the major air pollution control devices. This report presents results of the SNRB{trademark} Air Toxics Monitoring Project. In addition to the Introduction, a brief description of the test site, including the Boiler No. 8 and the SNRB{trademark} process, is included in Section H. The concentrations of air toxic emissions are presented in Section II according to compound class. Material balances are included in Section IV for three major systems: boiler, electrostatic precipitator, and SNRB{trademark}. Emission factors and removal efficiencies are also presented according to compound class in Sections V and VI, respectively. A data evaluation is provided in Section VII.

  15. Air toxics from heavy oil production and consumption

    SciTech Connect

    Lipfert, F.W.; DePhillips, M.P.; Moskowitz, P.D.

    1992-12-22

    This report assesses the potential impact of recent Federal and state regulations for airborne toxic substances on the production and consumption of heavy fuel oils. Emissions of nickel from heavy oil production in California are considered in some detail, in conjunction with California state regulations for toxic emissions. Although the use of thermal energy from heavy crude oils could in theory be impacted by toxic air pollution regulations, recent trends towards the use of natural gas for the required extraction energy appear to provide substantial relief, in addition to reducing emissions of criteria air pollutants. However, the consumption of residual fuel oils containing toxic metals could result in higher population exposures to these substances and their attendant risks may be worthy of more detailed analysis.

  16. Advanced combustor design concept to control NOx and air toxics

    SciTech Connect

    Eddings, E.G.; Pershing, D.W.; Molina, A.; Sarofim, A.F.; Spinti, J.P.; Veranth, J.

    1999-03-29

    Direct coal combustion needs to be a primary energy source for the electric utility industry and for heavy manufacturing during the next several decades because of the availability and economic advantage of coal relative to other fuels and because of the time required to produce major market penetration in the energy field. However, the major obstacle to coal utilization is a set of ever-tightening environmental regulations at both the federal and local level. It is, therefore, critical that fundamental research be conducted to support the development of low-emission, high-efficiency pulverized coal power systems. The objective of this program was to develop fundamental understanding regarding the impact of fuel and combustion changes on NOx formation, carbon burnout and air toxic emissions from pulverized coal (pc) combustion. During pc combustion, nitrogen in the coal can be oxidized to form nitrogen oxides (NO{sub x}). The 1990 Clean Air Act Amendments established much stricter NO{sub x} emissions limits for new and existing coal-fired plants, so there has been renewed interest in the processes by which NO{sub x} forms in pc flames. One of the least understood aspects of NO{sub x} formation from pc combustion is the process by which char-N (nitrogen remaining in the char after devolatilization) forms either NO{sub x} or N{sub 2}, and the development of a fundamental understanding of this process was a major focus of this research. The overall objective of this program was to improve the ability of combustion system designers and boiler manufacturers to build high efficiency, low emission pulverized coal systems by improving the design tools available to the industry. The specific program goals were to: Use laboratory experiments and modeling to develop fundamental understanding for a new submodel for char nitrogen oxidation (a critical piece usually neglected in most NOx models.); Use existing bench scale facilities to investigate alternative schemes to

  17. Emission factors of air toxics from semiconductor manufacturing in Korea.

    PubMed

    Eom, Yun-Sung; Hong, Ji-Hyung; Lee, Suk-Jo; Lee, Eun-Jung; Cha, Jun-Seok; Lee, Dae-Gyun; Bang, Sun-Ae

    2006-11-01

    The development of local, accurate emission factors is very important for the estimation of reliable national emissions and air quality management. For that, this study is performed for pollutants released to the atmosphere with source-specific emission tests from the semiconductor manufacturing industry. The semiconductor manufacturing industry is one of the major sources of air toxics or hazardous air pollutants (HAPs); thus, understanding the emission characteristics of the emission source is a very important factor in the development of a control strategy. However, in Korea, there is a general lack of information available on air emissions from the semiconductor industry. The major emission sources of air toxics examined from the semiconductor manufacturing industry were wet chemical stations, coating applications, gaseous operations, photolithography, and miscellaneous devices in the wafer fabrication and semiconductor packaging processes. In this study, analyses of emission characteristics, and the estimations of emission data and factors for air toxics, such as acids, bases, heavy metals, and volatile organic compounds from the semiconductor manufacturing process have been performed. The concentration of hydrogen chloride from the packaging process was the highest among all of the processes. In addition, the emission factor of total volatile organic compounds (TVOCs) for the packaging process was higher than that of the wafer fabrication process. Emission factors estimated in this study were compared with those of Taiwan for evaluation, and they were found to be of similar level in the case of TVOCs and fluorine compounds.

  18. Uneven Magnitude of Disparities in Cancer Risks from Air Toxics

    PubMed Central

    James, Wesley; Jia, Chunrong; Kedia, Satish

    2012-01-01

    This study examines race- and income-based disparities in cancer risks from air toxics in Cancer Alley, LA, USA. Risk estimates were obtained from the 2005 National Air Toxics Assessment and socioeconomic and race data from the 2005 American Community Survey, both at the census tract level. Disparities were assessed using spatially weighted ordinary least squares (OLS) regression and quantile regression (QR) for five major air toxics, each with cancer risk greater than 10−6. Spatial OLS results showed that disparities in cancer risks were significant: People in low-income tracts bore a cumulative risk 12% more than those in high-income tracts (p < 0.05), and those in black-dominant areas 16% more than in white-dominant areas (p < 0.01). Formaldehyde and benzene were the two largest contributors to the disparities. Contributions from emission sources to disparities varied by compound. Spatial QR analyses showed that magnitude of disparity became larger at the high end of exposure range, indicating worsened disparity in the poorest and most highly concentrated black areas. Cancer risk of air toxics not only disproportionately affects socioeconomically disadvantaged and racial minority communities, but there is a gradient effect within these groups with poorer and higher minority concentrated segments being more affected than their counterparts. Risk reduction strategies should target emission sources, risk driver chemicals, and especially the disadvantaged neighborhoods. PMID:23208297

  19. AIR TOXICS EMISSIONS FROM A VINYL SHOWER CURTAIN

    EPA Science Inventory

    The paper reports results of both static and dynamic chamber tests conducted to evaluate emission characteristics of air toxics from a vinyl shower Curtain. (NOTE: Due to the relatively low price and ease of installation, vinyl shower curtains have been widely used in bathrooms i...

  20. Background concentrations of 18 air toxics for North America.

    PubMed

    McCarthy, Michael C; Hafner, Hilary R; Montzka, Stephen A

    2006-01-01

    The U.S. Clean Air Act identifies 188 hazardous air pollutants (HAPs), or "air toxics," associated with adverse human health effects. Of these air toxics, 18 were targeted as the most important in a 10-City Pilot Study conducted in 2001 and 2002 as part of the National Air Toxics Trend Sites Program. In the present analysis, measurements available from monitoring networks in North America were used to estimate boundary layer background concentrations and trends of these 18 HAPs. The background concentrations reported in this study are as much as 85% lower than those reported in recent studies of HAP concentrations. Background concentrations of some volatile organic compounds were analyzed for trends at the 95% confidence level; only carbon tetrachloride (CCI4) and tetrachloroethylene decreased significantly in recent years. Remote background concentrations were compared with the one-in-a-million (i.e., 10(6)) cancer benchmarks to determine the possible causes of health risk in rural and remote areas; benzene, chloroform, formaldehyde, and chromium (Cr) fine particulate were higher than cancer benchmark values. In addition, remote background concentrations were found to contribute between 5% and 99% of median urban concentrations.

  1. Evaluating the Spatial Distribution of Toxic Air Contaminants in Multiple Ecosystem Indicators in the Sierra Nevada-Southern Cascades

    NASA Astrophysics Data System (ADS)

    Nanus, L.; Simonich, S. L.; Rocchio, J.; Flanagan, C.

    2013-12-01

    Toxic air contaminants originating from agricultural areas of the Central Valley in California threaten vulnerable sensitive receptors including surface water, vegetation, snow, sediments, fish, and amphibians in the Sierra Nevada-Southern Cascades region. The spatial distribution of toxic air contaminants in different ecosystem indicators depends on variation in atmospheric concentrations and deposition, and variation in air toxics accumulation in ecosystems. The spatial distribution of organic air toxics and mercury at over 330 unique sampling locations and sample types over two decades (1990-2009) in the Sierra Nevada-Southern Cascades region were compiled and maps were developed to further understand spatial patterns and linkages between air toxics deposition and ecological effects. Potential ecosystem impacts in the Sierra Nevada-Southern Cascades region include bioaccumulation of air toxics in both aquatic and terrestrial ecosystems, reproductive disruption, and immune suppression. The most sensitive ecological end points in the region that are affected by bioaccumulation of toxic air contaminants are fish. Mercury was detected in all fish and approximately 6% exceeded human consumption thresholds. Organic air toxics were also detected in fish yielding variable spatial patterns. For amphibians, which are sensitive to pesticide exposure and potential immune suppression, increasing trends in current and historic use pesticides are observed from north to south across the region. In other indicators, such as vegetation, pesticide concentrations in lichen increase with increasing elevation. Current and historic use pesticides and mercury were also observed in snowpack at high elevations in the study area. This study shows spatial patterns in toxic air contaminants, evaluates associated risks to sensitive receptors, and identifies data gaps. Future research on atmospheric modeling and information on sources is needed in order to predict which ecosystems are the

  2. AIR Model Preflight Analysis

    NASA Technical Reports Server (NTRS)

    Tai, H.; Wilson, J. W.; Maiden, D. L.

    2003-01-01

    The atmospheric ionizing radiation (AIR) ER-2 preflight analysis, one of the first attempts to obtain a relatively complete measurement set of the high-altitude radiation level environment, is described in this paper. The primary thrust is to characterize the atmospheric radiation and to define dose levels at high-altitude flight. A secondary thrust is to develop and validate dosimetric techniques and monitoring devices for protecting aircrews. With a few chosen routes, we can measure the experimental results and validate the AIR model predictions. Eventually, as more measurements are made, we gain more understanding about the hazardous radiation environment and acquire more confidence in the prediction models.

  3. IPM Analysis of the Final Mercury and Air Toxics Standards (MATS)

    EPA Pesticide Factsheets

    EPA used version 4.10_MATS of the Integrated Planning Model (IPM) to analyze the impact of the Mercury and Air Toxics Standards (MATS) rule on the U.S. electric power sector. Learn about the results and view links to documentation.

  4. Air toxics risk standards: are we addressing the real problems?

    SciTech Connect

    Laurie Miller; Richard Becker; Ted Cromwell

    2005-06-01

    Cost-effective risk reductions from major stationary emission sources have seen significant progress. EPA and state data demonstrate that their programs have dramatically reduced emissions and risk from these sources. Analyses indicate that the next generation of risk reductions for stationary sources will be provide little risk reduction, but will be much more costly and more challenging from a policy perspective. Facing these tough choices, EPA and state regulators should, with stakeholder input, be developing scientifically driven and cost-effective approaches to provide the public with honest answers and results. Air toxics risk policies and programs must prioritize and address significant remaining air toxics risks, educate and communicate to the public about the decision alternatives, build support for a holistic approach and openly communicate results. 6 refs.

  5. 77 FR 30274 - The Commission's Role Regarding the Environmental Protection Agency's Mercury and Air Toxics...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-22

    ... Mercury and Air Toxics Standards; Policy Statement on the Commission's Role Regarding the Environmental Protection Agency's Mercury and Air Toxics Standards Before Commissioners: Jon Wellinghoff, Chairman; Philip... for Administrative Orders (AO) to operate in noncompliance with EPA's Mercury and Air Toxics...

  6. A comparison of PAMS and air toxics measurements

    NASA Astrophysics Data System (ADS)

    Sistla, Gopal; Aleksic, Nenad

    One of the requirements of the 1990 Clean Air Act Amendments (CAA) is that 1-h ozone nonattainment areas that are classified severe or higher category are required to operate a network of photochemical assessment monitors (PAMS) to provide hourly measurements of volatile organic compounds (VOCs) comprising of Carbon number <12 (C2-C12), along with carbonyl measurements at 3-h intervals during the summer ozone season. Often collocated with PAMS are 24-h-integrated canister and cartridge-based measurements of selected air toxic compounds, thereby providing an opportunity for inter-comparison and validation of both sets of data. In this study, we report such a comparison and estimates of trend for benzene, m-, p- and o-xylene, toluene, ethylbenzene, 1,2,4-trimethylbenzene, formaldehyde and acetaldehyde at Bronx, NY. The analysis shows that hourly PAMS and 24-h-integrated air toxics are in good agreement with each other exhibiting similar trends and that the PAMS with the higher temporal resolution offers information on excursions of the toxic compounds that would be quite useful in assessment of acute health effects. These findings were also found to be applicable to other locations such as South De Kalb, GA; Gary, IN and Lynn, MA.

  7. Predictive Modeling of Developmental Toxicity

    EPA Science Inventory

    The use of alternative methods in conjunction with traditional in vivo developmental toxicity testing has the potential to (1) reduce cost and increase throughput of testing the chemical universe, (2) prioritize chemicals for further targeted toxicity testing and risk assessment,...

  8. Ambient and Emission Trends of Toxic Air Contaminants in California.

    PubMed

    Propper, Ralph; Wong, Patrick; Bui, Son; Austin, Jeff; Vance, William; Alvarado, Álvaro; Croes, Bart; Luo, Dongmin

    2015-10-06

    After initiating a toxic air contaminant (TAC) identification and control program in 1984, the California Air Resources Board adopted regulations to reduce TAC emissions from cars, trucks, stationary sources, and consumer products. This study quantifies ambient concentration and emission trends for the period 1990-2012 for seven TACs that are responsible for most of the known cancer risk associated with airborne exposure in California. Of these seven, diesel particulate matter (DPM) is the most important; however DPM is not measured directly. Based on a novel surrogate method, DPM concentrations declined 68%, even though the state's population increased 31%, diesel vehicle-miles-traveled increased 81%, and the gross state product (GSP) increased 74%. Based on monitoring data, concentrations of benzene, 1,3-butadiene, perchloroethylene, and hexavalent chromium declined 88-94%. Also, the ambient and emissions trends for each of these four TACs were similar. Furthermore, these declines generally occurred earlier in California than elsewhere. However, formaldehyde and acetaldehyde, which are formed in the air photochemically from volatile organic compounds (VOCs), declined only 20-21%. The collective cancer risk from exposure to these seven reviewed TACs declined 76%. Significant reduction in cancer risk to California residents from implementation of air toxics controls (especially for DPM) is expected to continue.

  9. PETROTOX: an aquatic toxicity model for petroleum substances.

    PubMed

    Redman, Aaron D; Parkerton, Thomas F; McGrath, Joy A; Di Toro, Dominic M

    2012-11-01

    A spreadsheet model (PETROTOX) is described that predicts the aquatic toxicity of complex petroleum substances from petroleum substance composition. Substance composition is characterized by specifying mass fractions in constituent hydrocarbon blocks (HBs) based on available analytical information. The HBs are defined by their mass fractions within a defined carbon number range or boiling point interval. Physicochemical properties of the HBs are approximated by assigning representative hydrocarbons from a database of individual hydrocarbons with associated physicochemical properties. A three-phase fate model is used to simulate the distribution of each structure among the water-, air-, and oil-phase liquid in the laboratory test system. Toxicity is then computed based on the predicted aqueous concentrations and aquatic toxicity of each structure and the target lipid model. The toxicity of the complex substance is computed assuming additivity of the contribution of the individual assigned hydrocarbons. Model performance was evaluated by using direct comparisons with measured toxicity data for petroleum substances with sufficient analytical characterization to run the model. Indirect evaluations were made by comparing predicted toxicity distributions using analytical data on petroleum substances from different product categories with independent, empirical distributions of toxicity data available for the same categories. Predictions compared favorably with measured aquatic toxicity data across different petroleum substance categories. These findings demonstrate the utility of PETROTOX for assessing environmental hazards of petroleum substances given knowledge of substance composition.

  10. Air toxics evaluation of ABB Combustion Engineering Low-Emission Boiler Systems

    SciTech Connect

    Wesnor, J.D.

    1993-10-26

    The specific goals of the program are to identify air toxic compounds that might be emmitted from the new boiler with its various Air Pollution Control device for APCD alternatives in levels of regulatory concern. For the compounds thought to be of concern, potential air toxic control methodologies will be suggested and a Test Protocol will be written to be used in the Proof of Concept and full scale tests. The following task was defined: Define Replations and Standards; Identify Air Toxic Pollutants of Interest to Interest to Utility Boilers; Assesment of Air Toxic By-Products; State of the Art Assessment of Toxic By-Product Control Technologies; and Test Protocol Definition.

  11. Air toxic emissions from snowmobiles in Yellowstone National Park.

    PubMed

    Zhou, Yong; Shively, David; Mao, Huiting; Russo, Rachel S; Pape, Bruce; Mower, Richard N; Talbot, Robert; Sive, Barkley C

    2010-01-01

    A study on emissions associated with oversnow travel in Yellowstone National Park (YNP) was conducted for the time period of February 13-16, 2002 and February 12-16, 2003. Whole air and exhaust samples were characterized for 85 volatile organic compounds using gas chromatography. The toxics including benzene, toluene, ethylbenzene, xylenes (p-, m-, and o-xylene), and n-hexane, which are major components of two-stroke engine exhaust, show large enhancements during sampling periods resulting from increased snowmobile traffic. Evaluation of the photochemical history of air masses sampled in YNP revealed that emissions of these air toxics were (i) recent, (ii) persistent throughout the region, and (iii) consistent with the two-stroke engine exhaust sample fingerprints. The annual fluxes were estimated to be 0.35, 1.12, 0.24, 1.45, and 0.36 Gg yr(-1) for benzene, toluene, ethylbenzene, xylenes, and n-hexane, respectively, from snowmobile usage in YNP. These results are comparable to the flux estimates of 0.23, 0.77, 0.17, and 0.70 Gg yr(-1) for benzene, toluene, ethylbenzene, and xylenes, respectively, that were derived on the basis of (i) actual snowmobile counts in the Park and (ii) our ambient measurements conducted in 2003. Extrapolating these results, annual emissions from snowmobiles in the U.S. appear to be significantly higher than the values from the EPA National Emissions Inventory (1999). Snowmobile emissions represent a significant fraction ( approximately 14-21%) of air toxics with respect to EPA estimates of emissions by nonroad vehicles. Further investigation is warranted to more rigorously quantify the difference between our estimates and emission inventories.

  12. Retinoblastoma and ambient exposure to air toxics in the perinatal period

    PubMed Central

    Heck, Julia E.; Park, Andrew S.; Qiu, Jiaheng; Cockburn, Myles; Ritz, Beate

    2014-01-01

    We examined ambient exposure to specific air toxics in the perinatal period in relation to retinoblastoma development. Cases were ascertained from California Cancer Registry records of children diagnosed 1990–2007 and matched to California birth certificates. Controls were randomly selected from state birth records for the same time period. We chose 27 air toxics for the present study that had been listed as possible, probable, or established human carcinogens by the International Agency for Research on Cancer. Children (103 cases and 30,601 controls) included in the study lived within 5 miles (~8K) of an air pollution monitor. Using logistic regression analyses, we modeled the risk of retinoblastoma due to air toxics exposure, separately for exposures in pregnancy and the first year of life. With a per interquartile range increase in air toxics exposure, retinoblastoma risk was found to be increased with pregnancy exposure to benzene (OR=1.67, 95%CI 1.06, 2.64) and other toxics which primarily arise from gasoline and diesel combustion: toluene, 1,3 butadiene, ethyl benzene, ortho-xylene, and meta/para-xylene; these 6 toxics were highly correlated. Retinoblastoma risk was also increased with pregnancy exposure to chloroform (OR=1.35, 95%CI 1.07, 1.70), chromium (OR=1.29, 95%CI 1.04, 1.60), para-dichlorobenzene (OR=1.24, 95%CI 1.04, 1.49), nickel (OR=1.48, 95%CI 1.08, 2.01), and in the first year of life, acetaldehyde (OR=1.62, 95%CI 1.06, 2.48). Sources of these agents are discussed. PMID:24280682

  13. [Toxic fungi in Buenos Aires City and surroundings].

    PubMed

    Romano, Gonzalo M; Iannone, Leopoldo; Novas, María V; Carmarán, Cecilia; Romero, Andrea I; López, Silvia E; Lechner, Bernardo E

    2013-01-01

    In Facultad de Ciencias Exactas y Naturales,Universidad de Buenos Aires there is a service called Servicio de Identificación de Hongos Tóxicos, directed by researchers of the Program of Medicinal Plants and Fungi Involved in Biological Degradation (PROPLAME-PRHIDEB, CONICET) that assist hospitals and other health establishments, identifying the different samples of fungi and providing information about their toxicity, so that patients can receive the correct treatment. The objective of the present study was to analyze all the cases received from 1985 to 2012. This analysis permitted the confection of a table identifying the most common toxic species. The information gathered revealed that 47% of the patients were under 18 years of age and had eaten basidiomes; the remaining 53% were adults who insisted that they were able to distinguish edible from toxic mushrooms. Chlorophyllum molybdites turned out to be the main cause of fungal intoxication in Buenos Aires, which is commonly confused with Macrolepiota procera, an edible mushroom. In the second place Amanita phalloides was registered, an agaric known to cause severe symptoms after a long period of latency (6-10 hours), and which can lead to hepatic failure even requiring a transplant to prevent severe internal injuries or even death, is not early and correctly treated.

  14. Quantitative Predictive Models for Systemic Toxicity (SOT)

    EPA Science Inventory

    Models to identify systemic and specific target organ toxicity were developed to help transition the field of toxicology towards computational models. By leveraging multiple data sources to incorporate read-across and machine learning approaches, a quantitative model of systemic ...

  15. An Evaluation of EPA's National-Scale Air Toxics Assessment (NATA): Comparison with Benzene Measurements in Detroit, Michigan

    EPA Science Inventory

    The U.S. EPA periodically evaluates ambient concentrations, human exposures, and health risks for 180 hazardous air pollutants plus diesel particulate matter using modeled estimates from the National-Scale Air Toxics Assessment (NATA). NATA publishes estimates at the spatial reso...

  16. Notification: Background Investigation Services EPA’s Efforts to Incorporate Environmental Justice Into Clean Air Act Inspections for Air Toxics

    EPA Pesticide Factsheets

    Project #OPE-FY14-0017, March 7, 2014. The OIG plans to begin the preliminary research phase of an evaluation of the EPA's efforts to incorporate environmental justice into Clean Air Act (CAA) inspections for air toxics.

  17. Combinatorial QSAR Modeling of Rat Acute Toxicity by Oral Exposure

    EPA Science Inventory

    Quantitative Structure-Activity Relationship (QSAR) toxicity models have become popular tools for identifying potential toxic compounds and prioritizing candidates for animal toxicity tests. However, few QSAR studies have successfully modeled large, diverse mammalian toxicity end...

  18. Segregation and black/white differences in exposure to air toxics in 1990.

    PubMed Central

    Lopez, Russ

    2002-01-01

    I examined non-Hispanic Black and non-Hispanic White differences in exposure to noncriteria air pollutants in 44 U.S. Census Bureau-defined metropolitan areas with populations greater than one million, using data on air toxics concentrations prepared for the U.S. Environmental Protection Agency as part of its Cumulative Exposure Project combined with U.S. census data. I measured differences in exposure to air toxics through the calculation of a net difference score, which is a statistical measure used in income inequality analysis to measure inequality over the whole range of exposures. The scores ranged from 11.52 to 83.60. In every metropolitan area, non-Hispanic Blacks are more likely than non-Hispanic Whites to be living in tracts with higher total modeled air toxics concentrations. To assess potential reasons for such a wide variation in exposure differences, I performed a multiple regression analysis with the net difference score as the dependent variable. Independent variables initially included were as follows: the dissimilarity index (to measure segregation), Black poverty/White poverty (to control for Black/White economic differences), population density and percentage of persons traveling to work who drive to work (alone and in car pools), and percentage of workforce employed in manufacturing (factors affecting air quality). After an initial analysis I eliminated from the model the measures of density and the persons driving to work because they were statistically insignificant, they did not add to the predictive power of the model, and their deletion did not affect the other variables. The final model had an R(2) of 0.56. Increased segregation is associated with increased disparity in potential exposure to air pollution. PMID:11929740

  19. 3 CFR - Flexible Implementation of the Mercury and Air Toxics Standards Rule

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 3 The President 1 2012-01-01 2012-01-01 false Flexible Implementation of the Mercury and Air... Flexible Implementation of the Mercury and Air Toxics Standards Rule Memorandum for the Administrator of... the final Mercury and Air Toxics Standards rule for power plants (the “MATS Rule”) represents a...

  20. 76 FR 80727 - Flexible Implementation of the Mercury and Air Toxics Standards Rule

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-27

    ... Documents#0;#0; ] Memorandum of December 21, 2011 Flexible Implementation of the Mercury and Air Toxics... the Environmental Protection Agency (EPA), of the final Mercury and Air Toxics Standards rule for... comments, prescribes standards under section 112 of the Clean Air Act to control emissions of mercury...

  1. SIMULATING URBAN AIR TOXICS OVER CONTINENTAL AND URBAN SCALES

    EPA Science Inventory

    The US EPA is evaluating a version of the CMAQ model to support risk assessment for the exposure to Hazardous Air Pollutants (HAPs). The model uses a variant of the CB4 chemical mechanism to simulate ambient concentrations of twenty HAPs that exist primarily as gaseous compounds...

  2. Regulatory Actions - Final Mercury and Air Toxics Standards (MATS) for Power Plants

    EPA Pesticide Factsheets

    The U.S. Environmental Protection Agency (EPA) has proposed Mercury and Air Toxics Standards (MATS) for power plants to limit mercury, acid gases and other toxic pollution from power plants. This page describes Federal regulatory actions.

  3. Regulatory Actions - Proposed Mercury and Air Toxics Standards (MATS) for Power Plants

    EPA Pesticide Factsheets

    The U.S. Environmental Protection Agency (EPA) has proposed Mercury and Air Toxics Standards (MATS) for power plants to limit mercury, acid gases and other toxic pollution from power plants. This page includes supporting documentation and

  4. Emissions of air toxics from coal-fired boilers: Arsenic

    SciTech Connect

    Mendelsohn, M.H.; Huang, H.S.; Livengood, C.D.

    1994-08-01

    Concerns over emissions of hazardous air pollutants (air toxics) have emerged as a major environmental issue; the authority of the US Environmental Protection Agency to regulate such pollutants has been greatly expanded through passage of the Clean Air Act Amendments of 1990. Arsenic and arsenic compounds are of concern mainly because of their generally recognized toxicity. Arsenic is also regarded as one of the trace elements in coal subject to significant vaporization. This report summarizes and evaluates available published information on the arsenic content of coals mined in the United States, on arsenic emitted in coal combustion, and on the efficacy of various environmental control technologies for controlling airborne emissions. Bituminous and lignite coals have the highest mean arsenic concentrations, with subbituminous and anthracite coals having the lowest. However, all coal types show very significant variations in arsenic concentrations. Arsenic emissions from coal combustion are not well-characterized, particularly with regard to determination of specific arsenic compounds. Variations in emission, rates of more than an order of magnitude have been reported for some boiler types. Data on the capture of arsenic by environmental control technologies are available primarily for systems with cold electrostatic precipitators, where removals of approximately 50 to 98% have been reported. Limited data for wet flue-gas-desulfurization systems show widely varying removals of from 6 to 97%. On the other hand, waste incineration plants report removals in a narrow range of from 95 to 99%. This report briefly reviews several areas of research that may lead to improvements in arsenic control for existing flue-gas-cleanup technologies and summarizes the status of analytical techniques for measuring arsenic emissions from combustion sources.

  5. Optimizing electric utility air toxics compliance with other titles of the Clean Air Act

    SciTech Connect

    Loeb, A.P.; South, D.W.

    1993-12-31

    This paper provides an overview of regulatory issues under Title III of the Clean Air Act Amendments that could affect electric utilities. Title III contains provisions relating to hazardous air pollutants (HAPs) and provides special treatment for electric utilities. Generally, this discussion documents that if utility toxic emissions are regulated, one of the chief difficulties confronting utilities will be the lack of coordination between Title III and other titles of the Act. The paper concludes that if the US Environmental Protection Agency (EPA) determines that regulation of utility HAPs is warranted under Title III, savings can be realized from flexible compliance treatment.

  6. Air modeling: Air dispersion models; regulatory applications and technological advances

    SciTech Connect

    Miller, M.; Liles, R.

    1995-09-01

    Air dispersion models are a useful and practical tool for both industry and regulatory agencies. They serve as tools for engineering, permitting, and regulations development. Their cost effectiveness and ease of implementation compared to ambient monitoring is perhaps their most-appealing trait. Based on the current momentum within the U.S. EPA to develop better models and contain regulatory burdens on industry, it is likely that air dispersion modeling will be a major player in future air regulatory initiatives.

  7. National Air Toxics Information clearinghouse: Bibliography of selected reports and Federal Register notices related to air toxics. Volume 3. Citations, 1989

    SciTech Connect

    Pickett, D.F.; Owen, C.A.; Norris, C.E.

    1989-07-01

    The purpose of the bibliography is to provide State and local agencies with citations to reports and Federal Register notices useful to them in developing and operating air toxics control programs. The reports selected for the bibliography were published by the following agencies: U.S. EPA, NAS, NCI, NIEHS, NTP, NIOSH, ATSDR, CPSC, and WHO, including the International Agency for Research on Cancer. Relevant reports published by various State and local agencies are also included in the edition. The edition of the bibliography updates the cumulative bibliography previously published by the National Air Toxics Information Clearinghouse, Bibliography of Selected Reports and Federal Register Notices Related to Air Toxics, July 1988.

  8. Air toxics provisions of the Clean Air Act: Potential impacts on energy

    SciTech Connect

    Hootman, H.A.; Vernet, J.E.

    1991-11-01

    This report provides an overview of the provisions of the Clean Air Act and its Amendments of 1990 that identify hazardous air pollutant (HAP) emissions and addresses their regulation by the US Environmental Protection Agency (EPA). It defines the major energy sector sources of these HAPs that would be affected by the regulations. Attention is focused on regulations that would cover coke oven emissions; chromium emission from industrial cooling towers and the electroplating process; HAP emissions from tank vessels, asbestos-related activities, organic solvent use, and ethylene oxide sterilization; and emissions of air toxics from municipal waste combustors. The possible implications of Title III regulations for the coal, natural gas, petroleum, uranium, and electric utility industries are examined. The report discusses five major databases of HAP emissions: (1) TRI (EPA`s Toxic Release Inventory); (2) PISCES (Power Plant Integrated Systems: Chemical Emissions Studies developed by the Electric Power Research Institute); (3) 1985 Emissions Inventory on volatile organic compounds (used for the National Acid Precipitation Assessment Program); (4) Particulate Matter Species Manual (EPA); and (5) Toxics Emission Inventory (National Aeronautics and Space Administration). It also offers information on emission control technologies for municipal waste combustors.

  9. Air toxics provisions of the Clean Air Act: Potential impacts on energy

    SciTech Connect

    Hootman, H.A.; Vernet, J.E.

    1991-11-01

    This report provides an overview of the provisions of the Clean Air Act and its Amendments of 1990 that identify hazardous air pollutant (HAP) emissions and addresses their regulation by the US Environmental Protection Agency (EPA). It defines the major energy sector sources of these HAPs that would be affected by the regulations. Attention is focused on regulations that would cover coke oven emissions; chromium emission from industrial cooling towers and the electroplating process; HAP emissions from tank vessels, asbestos-related activities, organic solvent use, and ethylene oxide sterilization; and emissions of air toxics from municipal waste combustors. The possible implications of Title III regulations for the coal, natural gas, petroleum, uranium, and electric utility industries are examined. The report discusses five major databases of HAP emissions: (1) TRI (EPA's Toxic Release Inventory); (2) PISCES (Power Plant Integrated Systems: Chemical Emissions Studies developed by the Electric Power Research Institute); (3) 1985 Emissions Inventory on volatile organic compounds (used for the National Acid Precipitation Assessment Program); (4) Particulate Matter Species Manual (EPA); and (5) Toxics Emission Inventory (National Aeronautics and Space Administration). It also offers information on emission control technologies for municipal waste combustors.

  10. A METHOD OF ASSESSING AIR TOXICS CONCENTRATIONS IN URBAN AREAS USING MOBILE PLATFORM MEASUREMENTS

    EPA Science Inventory

    The objective of this paper is to demonstrate an approach to characterize the spatial variability in ambient air concentrations using mobile platform measurements. This approach may be useful for air toxic assessments in Environmental Justice applications, epidemiological studies...

  11. Potential Air Toxics Hot Spots in Truck Terminals and Cabs

    PubMed Central

    Smith, Thomas J.; Davis, Mary E.; Hart, Jaime E.; Blicharz, Andrew; Laden, Francine; Garshick, Eric

    2016-01-01

    INTRODUCTION Hot spots are areas where concentrations of one or more air toxics — organic vapors or particulate matter (PM) — are expected to be elevated. The U.S. Environmental Protection Agency’s (EPA*) screening values for air toxics were used in our definition of hot spots. According to the EPA, a screening value “is used to indicate a concentration of a chemical in the air to which a person could be continually exposed for a lifetime … and which would be unlikely to result in a deleterious effect (either cancer or noncancer health effects)” (U.S. EPA 2006). Our characterization of volatile organic compounds (VOCs; namely 18 hydrocarbons, methyl tert-butyl ether [MTBE], acetone, and aldehydes) was added onto our ongoing National Cancer Institute–funded study of lung cancer and particulate pollutant concentrations (PM with an aerodynamic diameter ≤ 2.5 µm [PM2.5], elemental carbon [EC], and organic carbon [OC]) and source apportionment of the U.S. trucking industry. We focused on three possible hot spots within the trucking terminals: upwind background areas affected by nearby industrial parks; downwind areas affected by upwind and terminal sources; and the loading docks and mechanic shops within terminal as well as the interior of cabs of trucks being driven on city, suburban, and rural streets and on highways. METHODS In Phase 1 of our study, 15 truck terminals across the United States were each visited for five consecutive days. During these site visits, sorbent tubes were used to collect 12-hour integrated samples of hydrocarbons and aldehydes from upwind and downwind fence-line locations as well as inside truck cabs. Meteorologic data and extensive site information were collected with each sample. In Phase 2, repeat visits to six terminals were conducted to test the stability of concentrations across time and judge the representativeness of our previous measurements. During the repeat site visits, the sampling procedure was expanded to

  12. Spatial variations of particulate matter and air toxics in communities adjacent to the Port of Oakland.

    PubMed

    Fujita, Eric M; Campbell, David E; Arnott, W Patrick; Lau, Virginia; Martien, Philip T

    2013-12-01

    The Bay Area Air Quality Management District (BAAQMD) sponsored the West Oakland Monitoring Study (WOMS) to provide supplemental air quality monitoring that will be used by the BAAQMD to evaluate local-scale dispersion modeling of diesel emissions and other toxic air contaminants for the area within and around the Port of Oakland. The WOMS was conducted during two seasonal periods of 4 weeks in summer 2009 and winter 2009/2010. Monitoring data showed spatial patterns of pollutant concentrations that were generally consistent with proximity to vehicle traffic. Concentrations of directly emitted pollutants were highest on heavily traveled roads with consistently lower concentrations away from the roadways. Pollutants that have higher emission rates from diesel trucks (nitric oxide, black carbon) tended to exhibit sharper gradients than pollutants that are largely associated with gasoline vehicles, such as carbon monoxide and volatile organic compounds, including benzene, toluene, ethylbenzene, and xylenes (BTEX). BTEX concentrations in West Oakland were similar to those measured at the three air toxics monitoring network sites in the Bay Area (San Francisco, Fremont, and San Jose). Aldehyde levels were higher in Fremont and San Jose than in West Oakland, reflecting greater contributions from photo-oxidation of hydrocarbons downwind of the Bay Area. A 2005 modeling-based health risk assessment of diesel particulate matter concentrations is consistent with aerosol carbon concentrations measured during the WOMS after adjusting for recent mitigation measures and improved estimates of heavy-duty truck traffic volumes.

  13. Modeling toxic compounds from nitric oxide emission measurements

    NASA Astrophysics Data System (ADS)

    Vallero, Daniel A.; Peirce, Jeffrey; Cho, Ki Don

    Determining the amount and rate of degradation of toxic pollutants in soil and groundwater is difficult and often requires invasive techniques, such as deploying extensive monitoring well networks. Even with these networks, degradation rates across entire systems cannot readily be extrapolated from the samples. When organic compounds are degraded by microbes, especially nitrifying bacteria, oxides or nitrogen (NO x) are released to the atmosphere. Thus, the flux of nitric oxide (NO) from the soil to the lower troposphere can be used to predict the rate at which organic compounds are degraded. By characterizing and applying biogenic and anthropogenic processes in soils the rates of degradation of organic compounds. Toluene was selected as a representative of toxic aromatic compounds, since it is inherently toxic, it is a substituted benzene compound and is listed as a hazardous air pollutant under Section 12 of the Clean Air Act Amendments of 1990. Measured toluene concentrations in soil, microbial population growth and NO fluxes in chamber studies were used to develop and parameterize a numerical model based on carbon and nitrogen cycling. These measurements, in turn, were used as indicators of bioremediation of air toxic (i.e. toluene) concentrations. The model found that chemical concentration, soil microbial abundance, and NO production can be directly related to the experimental results (significant at P < 0.01) for all toluene concentrations tested. This indicates that the model may prove useful in monitoring and predicting the fate of toxic aromatic contaminants in a complex soil system. It may also be useful in predicting the release of ozone precursors, such as changes in reservoirs of hydrocarbons and oxides of nitrogen. As such, the model may be a tool for decision makers in ozone non-attainment areas.

  14. 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...

  15. Determination of carbonyl compounds by HPLC/UV analysis in the CASTNet Air Toxics Monitoring Program (CATMP)

    SciTech Connect

    Weichert, B.A.; Baker, R.D.; Johnson, B.T.; Winslow, M.G.

    1994-12-31

    The determination of carbonyl compounds in ambient air is one of the analytical requirements of the Environmental Protection Agency`s (EPA`s) Clean Air Status and Trends Network (CASTNet) Air Toxics Monitoring Program (CATMP). The CATMP was established in 1993 by EPA to reactivate and operate the Urban Air Toxics Monitoring Program (UATMP). The purpose of the program is to establish baseline toxics concentrations, develop air emission inventories, and to identify air toxic sources using chemical mass balance modeling techniques. 1993 results for the CATMP analysis of carbonyl compounds by method TO-11 are presented. Samples were collected using Waters` dinitrophenyl hydrazine (DNPN) impregnated cartridges and analyzed using high performance liquid chromatography (HPLC) with ultraviolet (UV) detection. A regulatory program approach to quality control was taken to insure that all aspects of shipping, sampling and analysis contained sufficient controls in order to produce data of acceptable and consistent precision and accuracy. Database presentations will include the overall quality assurance approach, quality control measurements, and sample results from eight sites. An examination of background interferences detected in the various control samples also is discussed.

  16. Impact of underestimating the effects of cold temperature on motor vehicle start emissions of air toxics in the United States.

    PubMed

    Cook, Richard; Touma, Jawad S; Fernandez, Antonio; Brzezinski, David; Bailey, Chad; Scarbro, Carl; Thurman, James; Strum, Madeleine; Ensley, Darrell; Baldauf, Richard

    2007-12-01

    Analyses of U.S. Environmental Protection Agency (EPA) certification data, California Air Resources Board surveillance testing data, and EPA research testing data indicated that EPA's MOBILE6.2 emission factor model substantially underestimates emissions of gaseous air toxics occurring during vehicle starts at cold temperatures for light-duty vehicles and trucks meeting EPA Tier 1 and later standards. An unofficial version of the MOBILE6.2 model was created to account for these underestimates. When this unofficial version of the model was used to project emissions into the future, emissions increased by almost 100% by calendar year 2030, and estimated modeled ambient air toxics concentrations increased by 6-84%, depending on the pollutant. To address these elevated emissions, EPA recently finalized standards requiring reductions of emissions when engines start at cold temperatures.

  17. Developmental Toxicity Assays Using the Drosophila Model

    PubMed Central

    Rand, Matthew D.; Montgomery, Sara L.; Prince, Lisa; Vorojeikina, Daria

    2014-01-01

    The fruit fly (Drosophila melanogaster) has long been a premier model for developmental biologists and geneticists. The utility of Drosophila for toxicology studies has only recently gained broader recognition as a tool to elaborate molecular genetic mechanisms of toxic substances. In this article two practical applications of Drosophila for developmental toxicity assays are described. The first assay takes advantage of newly developed methods to render the fly embryo accessible to small molecules, toxicants and drugs. The second assay engages straightforward exposures to developing larvae and easy to score outcomes of adult development. With the extensive collections of flies that are publicly available and the ease with which to create transgenic flies, these two assays have a unique power for identifying and characterizing molecular mechanisms and cellular pathways specific to the mode of action of a number of toxicants and drugs. PMID:24789363

  18. Consensus Modeling of Oral Rat Acute Toxicity

    EPA Science Inventory

    An acute toxicity dataset (oral rat LD50) with about 7400 compounds was compiled from the ChemIDplus database. This dataset was divided into a modeling set and a prediction set. The compounds in the prediction set were selected so that they were present in the modeling set used...

  19. Air Toxics under the Big Sky: A Real-World Investigation to Engage High School Science Students

    ERIC Educational Resources Information Center

    Adams, Earle; Smith, Garon; Ward, Tony J.; Vanek, Diana; Marra, Nancy; Jones, David; Henthorn, Melissa; Striebel, Jim

    2008-01-01

    This paper describes a problem-based chemistry education model in which students perform scientific research on a local environmentally relevant problem. The project is a collaboration among The University of Montana and local high schools centered around Missoula, Montana. "Air Toxics under the Big Sky" involves high school students in collecting…

  20. Avian models for toxicity testing

    USGS Publications Warehouse

    Hill, E.F.; Hoffman, D.J.

    1984-01-01

    The use of birds as test models in experimental and environmental toxicology as related to health effects is reviewed, and an overview of descriptive tests routinely used in wildlife toxicology is provided. Toxicologic research on birds may be applicable to human health both directly by their use as models for mechanistic and descriptive studies and indirectly as monitors of environmental quality. Topics include the use of birds as models for study of teratogenesis and embryotoxicity, neurotoxicity, behavior, trends of environmental pollution, and for use in predictive wildlife toxicology. Uses of domestic and wild-captured birds are discussed.

  1. The C. elegans model in toxicity testing

    PubMed Central

    2016-01-01

    Abstract Caenorhabditis elegans is a small nematode that can be maintained at low cost and handled using standard in vitro techniques. Unlike toxicity testing using cell cultures, C. elegans toxicity assays provide data from a whole animal with intact and metabolically active digestive, reproductive, endocrine, sensory and neuromuscular systems. Toxicity ranking screens in C. elegans have repeatedly been shown to be as predictive of rat LD50 ranking as mouse LD50 ranking. Additionally, many instances of conservation of mode of toxic action have been noted between C. elegans and mammals. These consistent correlations make the case for inclusion of C. elegans assays in early safety testing and as one component in tiered or integrated toxicity testing strategies, but do not indicate that nematodes alone can replace data from mammals for hazard evaluation. As with cell cultures, good C. elegans culture practice (GCeCP) is essential for reliable results. This article reviews C. elegans use in various toxicity assays, the C. elegans model's strengths and limitations for use in predictive toxicology, and GCeCP. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. Journal of Applied Toxicology published by John Wiley & Sons Ltd. PMID:27443595

  2. Evaporation and air-stripping to assess and reduce ethanolamines toxicity in oily wastewater.

    PubMed

    Libralato, G; Ghirardini, A Volpi; Avezzù, F

    2008-05-30

    Toxicity from industrial oily wastewater remains a problem even after conventional activated sludge treatment process, because of the persistence of some toxicant compounds. This work verified the removal efficiency of organic and inorganic pollutants and the effects of evaporation and air-stripping techniques on oily wastewater toxicity reduction. In a lab-scale plant, a vacuum evaporation procedure at three different temperatures and an air-stripping stage were tested on oily wastewater. Toxicity reduction/removal was observed at each treatment step via Microtox bioassay. A case study monitoring real scale evaporation was also done in a full-size wastewater treatment plant (WWTP). To implement part of a general project of toxicity reduction evaluation, additional investigations took into account the monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA) role in toxicity definition after the evaporation phase, both as pure substances and mixtures. Only MEA and TEA appeared to contribute towards effluent toxicity.

  3. Air Modeling - Observational Meteorological Data

    EPA Pesticide Factsheets

    Observed meteorological data for use in air quality modeling consist of physical parameters that are measured directly by instrumentation, and include temperature, dew point, wind direction, wind speed, cloud cover, cloud layer(s), ceiling height,

  4. ULTRA HIGH EFFICIENCY ESP DEVELOPMENT FOR AIR TOXICS CONTROL

    SciTech Connect

    David K. Anderson

    1999-11-01

    Because more than 90 percent of U.S. coal-fired utility boilers are equipped with electrostatic precipitators (ESPs), retrofitable ESP technologies represent a logical approach towards achieving the Department of Energy's (DOE) goal of a major reduction in fine particulate and mercury emissions (air toxics) from coal based power systems. EPA's recent issuance of significantly tightened ambient air standards for particles smaller than 2.5 {micro}m (PM{sub 2.5}) creates a new urgency for developing cost-effective means to control fine particulate emissions. This challenge is compounded by the on-going switch in the utility industry to low-sulfur Powder River Basin (PRB) coals, that generate higher resistivity and difficult-to-collect fly ash. Particulate emissions can increase by a factor of ten when a utility switches to a low-sulfur coal. Numerous power plants are presently limited in operation by the inability of their ESPs to control opacity at high loads. In Phase I of this program, ABB investigated five technologies to improve the collection of fine particulate and trace metals in ESPs. These included: (1) flue-gas cooling, (2) flue-gas humidification, (3) pulsed energization, (4) wet ESP and precharger modules, and (5) sorbent injection for mercury control. Tests were conducted with an Eastern bituminous coal and a Powder River Basin sub-bituminous low-sulfur coal in an integrated pilot-scale combustor and ESP test facility. The impacts of the different retrofit technologies on ESP performance, individually and in combination, were evaluated indepth through advanced sampling and measurement techniques. In Phase II, the most promising concepts identified from Phase I testing, flue-gas cooling and humidification, pulsed energization, and sorbent injection at low flue-gas temperatures for mercury control, were integrated into a commercially oriented sub-scale system for field testing at Commonwealth Edison's Waukegan Unit No. 8. The main objective of the proposed

  5. National Air Toxics Information Clearinghouse: Bibliography of Selected Reports and Federal Register Notices Related to Air Toxics, Index 1989. Interim report

    SciTech Connect

    Pickett, D.F.; Owen, C.A.; Norris, C.E.

    1989-07-01

    The purpose of the bibliography is to provide State and local agencies with citations to reports and Federal Register notices useful to them in developing and operating air toxics control programs. The reports selected for the bibliography were published by the following agencies: U.S. EPA, NAS, NCI, NIEHS, NTP, NIOSH, ATSDR, CPSC, and WHO, including the International Agency for Research on Cancer. Relevant reports published by various State and local agencies are also included in this edition. This edition of the bibliography updates the cumulative bibliography previously published by the National Air Toxics Information Clearinghouse, Bibliography of Selected Reports and Federal Register Notices Related to Air Toxics, July 1988. The citations selected for the year were compiled from sources available through January 31, 1989.

  6. National air toxics information clearinghouse: Bibliography of selected reports and federal register notices related to air toxics. Index, 1992. Final report

    SciTech Connect

    Not Available

    1992-07-01

    The purpose of the bibliography is to provide State and local agencies with citations to report and Federal Register notices useful to them in developing and operating air toxics control programs. The reports selected for this bibliography were published by the following agencies: U.S. EPA, NAS, NCI, NIEHS, NTP, NIOSH, ATSDR, CPSC, and WHO, including the International Agency for Research on Cancer. Relevant reports published by various State and local agencies are also included in this edition. The edition of the bibliography updates the cumulative bibliography previously published by the National Air Toxics Information Clearinghouse, Bibliography of Selected Reports and Federal Register Notices Related to Air Toxics, July 1991. The citations selected for this year were compiled from sources available through January 31, 1992.

  7. Old, the new, the states, the evolution of the regulation of air toxics. Master's thesis

    SciTech Connect

    Vecera, D.R.

    1993-02-14

    The activism associated with America in the 1960s spilled over into many areas, one of which was a new environmental movement. A product of that movement was the Clean Air Act passed in 1970. The new law included a selection aimed specifically at controlling emissions of hazardous or toxic air pollutants. However, over the next 20 years there was very little government regulation of air toxics, and this section of the Clean Air Act was considered to be a resounding failure. What went wrong. How did this lofty goal to protect human health and the environment end up on the back burner. The article will address the idealism that led to the Clean Air Act legislation, in particular the air toxics program, and explore the realities that scuttled those ideals when it came time to implement the law.

  8. Regional Models for Sediment Toxicity Assessment

    EPA Science Inventory

    This paper investigates the use of empirical models to predict the toxicity of sediment samples within a region to laboratory test organisms based on sediment chemistry. In earlier work, we used a large nationwide database of matching sediment chemistry and marine amphipod sedim...

  9. Reactor modeling in heterogeneous photocatalysis: toxicity and biodegradability assessment.

    PubMed

    Satuf, M L; José, S; Paggi, J C; Brandi, R J; Cassano, A E; Alfano, O M

    2010-01-01

    Photocatalysis employing titanium dioxide is a useful method to degrade a wide variety of organic and inorganic pollutants from water and air. However, the application of this advanced oxidation process at industrial scale requires the development of mathematical models to design and scale-up photocatalytic reactors. In the present work, intrinsic kinetic expressions previously obtained in a laboratory reactor are employed to predict the performance of a bench scale reactor of different configuration and operating conditions. 4-Chlorophenol was chosen as the model pollutant. The toxicity and biodegradability of the irradiated mixture in the bench photoreactor was also assessed. Good agreement was found between simulation and experimental data. The root mean square error of the estimations was 9.9%. The photocatalytic process clearly enhances the biodegradability of the reacting mixture, and the initial toxicity of the pollutant was significantly reduced by the treatment.

  10. Petition for EPA action to protect communities from oil and gas wells toxic air pollution

    EPA Pesticide Factsheets

    Petition submitted by Earthjustice urging EPA to list oil and gas wells and associated equipment as an area sourcecategory and set national air toxics standards to protect public health from these sources.

  11. Biodiesel and Cold Temperature Effects on Speciated Mobile Source Air Toxics from Modern Diesel Trucks

    EPA Science Inventory

    Speciated volatile organic compounds (VOCs) with a particular focus on mobile source air toxics (MSATs) were measured in diesel exhaust from three heavy-duty trucks equipped with modern aftertreatment technologies. Emissions testing was conducted on a temperature controlled chass...

  12. Biodiesel and Cold Temperature Effect on Speciated Mobile Source Air Toxics from Modern Diesel Trucks

    EPA Science Inventory

    Speciated volatile organic compounds (VOCs) with a particular focus on mobile source air toxics (MSATs) were measured in diesel exhaust from three heavy-duty trucks equipped with modern aftertreatment technologies. Emissions testing was conducted on a temperature controlled chass...

  13. Report: EPA’s Method for Calculating Air Toxics Emissions for Reporting Results Needs Improvement

    EPA Pesticide Factsheets

    Report #2004-P-00012, March 31, 2004. Although the methods by which air toxics emissions are estimated have improved substantially, unvalidated assumptions and other limitations underlying the NTI continue to impact its use as a GPRA performance measure.

  14. Fact Sheet: Final Air Toxics Standards for Area Sources in the Chemical Manufacturing Industry

    EPA Pesticide Factsheets

    Fact sheet on the national air toxics standards issued October 16, 2009 by the Environmental Protection Agency (EPA) for smaller-emitting sources, known as area sources, in the chemical manufacturing industry.

  15. MONITORING THE AIR FOR TOXIC AND GENOTOXIC COMPOUNDS

    EPA Science Inventory

    A time-integrated sampling system interfaced with a toxicity-based assay is reported for monitoring volatile toxic industrial chemicals (TICs). Semipermeable membrane devices (SPMDs) using dimethyl sulfoxide (DMSO) as the fill solvent accumulated each of 17 TICs from the vapor p...

  16. Power Plants Likely Covered by the Mercury and Air Toxics Standards (MATS)

    EPA Pesticide Factsheets

    The U.S. Environmental Protection Agency (EPA) has proposed Mercury and Air Toxics Standards (MATS) for power plants to limit mercury, acid gases and other toxic pollution from power plants. Using Google Earth, this page locates power plants in your state.

  17. AIR QUALITY MODELING AT COARSE-TO-FINE SCALES IN URBAN AREAS

    EPA Science Inventory

    Urban air toxics control strategies are moving towards a community based modeling approach, with an emphasis on assessing those areas that experience high air toxic concentration levels, the so-called "hot spots". This approach will require information that accurately maps and...

  18. Air-quality-model update

    SciTech Connect

    Penner, J.E.; Walton, J.J.

    1982-01-15

    The Livermore Regional Air Quality Model (LIRAQ) has been updated and improved. This report describes the changes that have been made in chemistry, species treatment, and boundary conditions. The results of smog chamber simulations that were used to verify the chemistry as well as simulations of the entire air quality model for two prototype days in the Bay Area are reported. The results for the prototype day simulations are preliminary due to the need for improvement in meteorology fields, but they show the dependence and sensitivity of high hour ozone to changes in selected boundary and initial conditions.

  19. Modeling Respiratory Toxicity of Authentic Lunar Dust

    NASA Technical Reports Server (NTRS)

    Santana, Patricia A.; James, John T.; Lam, Chiu-Wing

    2010-01-01

    The lunar expeditions of the Apollo operations from the 60 s and early 70 s have generated awareness about lunar dust exposures and their implication towards future lunar explorations. Critical analyses on the reports from the Apollo crew members suggest that lunar dust is a mild respiratory and ocular irritant. Currently, NASA s space toxicology group is functioning with the Lunar Airborne Dust Toxicity Assessment Group (LADTAG) and the National Institute for Occupational Safety and Health (NIOSH) to investigate and examine toxic effects to the respiratory system of rats in order to establish permissible exposure levels (PELs) for human exposure to lunar dust. In collaboration with the space toxicology group, LADTAG and NIOSH the goal of the present research is to analyze dose-response curves from rat exposures seven and twenty-eight days after intrapharyngeal instillations, and model the response using BenchMark Dose Software (BMDS) from the Environmental Protection Agency (EPA). Via this analysis, the relative toxicities of three types of Apollo 14 lunar dust samples and two control dust samples, titanium dioxide (TiO2) and quartz will be determined. This will be executed for several toxicity endpoints such as cell counts and biochemical markers in bronchoaveolar lavage fluid (BALF) harvested from the rats.

  20. EPA'S CONTROL TECHNOLOGY APPROACH TO ASSISTING STATES AND REGIONS WITH AIR TOXICS PROBLEMS: FIVE CASE STUDIES

    EPA Science Inventory

    The paper discusses a new U.S. strategy to reduce public exposure to toxic air pollutants in the ambient air. he strategy calls for state and local authorities to take on more of the lead regulatory role. he shift in emphasis and responsibility prompted EPA's Offices of Research ...

  1. Carcinogenic Air Toxics Exposure and Their Cancer-Related Health Impacts in the United States.

    PubMed

    Zhou, Ying; Li, Chaoyang; Huijbregts, Mark A J; Mumtaz, M Moiz

    2015-01-01

    Public health protection from air pollution can be achieved more effectively by shifting from a single-pollutant approach to a multi-pollutant approach. To develop such multi-pollutant approaches, identifying which air pollutants are present most frequently is essential. This study aims to determine the frequently found carcinogenic air toxics or hazardous air pollutants (HAPs) combinations across the United States as well as to analyze the health impacts of developing cancer due to exposure to these HAPs. To identify the most commonly found carcinogenic air toxics combinations, we first identified HAPs with cancer risk greater than one in a million in more than 5% of the census tracts across the United States, based on the National-Scale Air Toxics Assessment (NATA) by the U.S. EPA for year 2005. We then calculated the frequencies of their two-component (binary), and three-component (ternary) combinations. To quantify the cancer-related health impacts, we focused on the 10 most frequently found HAPs with national average cancer risk greater than one in a million. Their cancer-related health impacts were calculated by converting lifetime cancer risk reported in NATA 2005 to years of healthy life lost or Disability-Adjusted Life Years (DALYs). We found that the most frequently found air toxics with cancer risk greater than one in a million are formaldehyde, carbon tetrachloride, acetaldehyde, and benzene. The most frequently occurring binary pairs and ternary mixtures are the various combinations of these four air toxics. Analysis of urban and rural HAPs did not reveal significant differences in the top combinations of these chemicals. The cumulative annual cancer-related health impacts of inhaling the top 10 carcinogenic air toxics included was about 1,600 DALYs in the United States or 0.6 DALYs per 100,000 people. Formaldehyde and benzene together contribute nearly 60 percent of the total cancer-related health impacts. Our study shows that although there are many

  2. Carcinogenic Air Toxics Exposure and Their Cancer-Related Health Impacts in the United States

    PubMed Central

    Zhou, Ying; Li, Chaoyang; Huijbregts, Mark A. J.; Mumtaz, M. Moiz

    2015-01-01

    Public health protection from air pollution can be achieved more effectively by shifting from a single-pollutant approach to a multi-pollutant approach. To develop such multi-pollutant approaches, identifying which air pollutants are present most frequently is essential. This study aims to determine the frequently found carcinogenic air toxics or hazardous air pollutants (HAPs) combinations across the United States as well as to analyze the health impacts of developing cancer due to exposure to these HAPs. To identify the most commonly found carcinogenic air toxics combinations, we first identified HAPs with cancer risk greater than one in a million in more than 5% of the census tracts across the United States, based on the National-Scale Air Toxics Assessment (NATA) by the U.S. EPA for year 2005. We then calculated the frequencies of their two-component (binary), and three-component (ternary) combinations. To quantify the cancer-related health impacts, we focused on the 10 most frequently found HAPs with national average cancer risk greater than one in a million. Their cancer-related health impacts were calculated by converting lifetime cancer risk reported in NATA 2005 to years of healthy life lost or Disability-Adjusted Life Years (DALYs). We found that the most frequently found air toxics with cancer risk greater than one in a million are formaldehyde, carbon tetrachloride, acetaldehyde, and benzene. The most frequently occurring binary pairs and ternary mixtures are the various combinations of these four air toxics. Analysis of urban and rural HAPs did not reveal significant differences in the top combinations of these chemicals. The cumulative annual cancer-related health impacts of inhaling the top 10 carcinogenic air toxics included was about 1,600 DALYs in the United States or 0.6 DALYs per 100,000 people. Formaldehyde and benzene together contribute nearly 60 percent of the total cancer-related health impacts. Our study shows that although there are many

  3. Hybrid regional air pollution models

    SciTech Connect

    Drake, R.L.

    1980-03-01

    This discussion deals with a family of air quality models for predicting and analyzing the fine particulate loading in the atmosphere, for assessing the extent and degree of visibility impairment, and for determining the potential of pollutants for increasing the acidity of soils and water. The major horizontal scales of interest are from 400km to 2000km; and the time scales may vary from several hours, to days, weeks, and a few months or years, depending on the EPA regulations being addressed. First the role air quality models play in the general family of atmospheric simulation models is described. Then, the characteristics of a well-designed, comprehensive air quality model are discussed. Following this, the specific objectives of this workshop are outlined, and their modeling implications are summarized. There are significant modeling differences produced by the choice of the coordinate system, whether it be the fixed Eulerian system, the moving Lagrangian system, or some hybrid of the two. These three systems are briefly discussed, and a list of hybrid models that are currently in use are given. Finally, the PNL regional transport model is outlined and a number of research needs are listed.

  4. Significance of 1,3-butadiene to the US air toxics regulatory effort.

    PubMed

    Morrow, N L

    2001-06-01

    Because of its prevalence, particularly as a combustion by-product, 1,3-butadiene is a particularly important air toxic. It plays a significant role in all air toxics regulatory efforts in the US. The various requirements of the Federal Clean Air Act (CAA) dealing with air toxics are reviewed and the significance of 1,3-butadiene in each area is discussed in light of what is known about its emissions and health effects. The impacts of the changes in the understanding of 1,3-butadiene cancer potency over the past 15 years demonstrates the possible impact of such benchmarks and the importance of using the best science in understanding public health risks.

  5. SIMULATION MODELS FOR ENVIRONMENTAL MULTIMEDIA ANALYSIS OF TOXIC CHEMICALS

    EPA Science Inventory

    Multimedia understanding of pollutant behavior in the environment is of particular concern for chemicals that are toxic and are subject to accumulation in the environmental media (air, soil, water, vegetation) where biota and human exposure is significant. Multimedia simulation ...

  6. Washability of air toxics in marketed Illinois coals

    SciTech Connect

    Demir, I.; Ruch, R.R.; Cahill, R.A.; Lytle, J.M.; Ho, K.K.

    1996-12-31

    The purpose of this study was to generate float-sink washability data to estimate how much more hazardous air pollutants content of Illinois coals can be decreased if advanced gravity based coal cleaning was used at preparation plants.

  7. The importance of toxicity in determining the impact of hazardous air pollutants on the respiratory health of children in Tennessee.

    PubMed

    Moore, Roberta J H; Hotchkiss, Julie L

    2016-09-01

    Respiratory diseases, exacerbated through point source pollution, are currently among the leading causes of hospitalization of children in the United States. This paper investigates the relationship between the proximity of hazardous air pollutants (HAPs) emitted from Toxic Release Inventory (TRI) facilities and the number of children diagnosed in hospitals with a respiratory disease in Tennessee. The importance of controlling for toxicity of those HAPs is of particular interest. Hospital discharge, socioeconomic, TRI emission, and HAP toxicity data are used to estimate, via Generalized Linear Methods, a logistic regression model describing the relationship between the percent of children living in a zip code area treated for respiratory illness and the average annual emissions over the previous 10 years of HAPs from TRI sites in that area. Controlling for area socioeconomic characteristics, we find that accounting for toxicity is important in uncovering the relationship between HAP emissions and respiratory health of children. A one standard deviation increase in toxicity-weighted emissions per 100 square miles is associated with an increase in the number of children diagnosed with asthma (chronic bronchitis) by about 1205 (260). The evidence suggests that, with a goal to improving children's respiratory health, monitoring the toxicity of chemicals being emitted is at least as important as simply monitoring total emission levels. This suggests that the EPA should consider making efforts toward establishing toxicity adjusted emission guidelines.

  8. APPLICATION OF JET REMPI AND LIBS TO AIR TOXIC MONITORING

    EPA Science Inventory

    The paper discusses three advanced, laser-based monitoring techniques that the EPA is assisting in developing for real time measurement of toxic aerosol compounds. One of the three techniques is jet resonance enhanced multiphoton ionization (Jet REMPI) coupled with a time-of-flig...

  9. Epidemiologic evidence for asthma and exposure to air toxics: linkages between occupational, indoor, and community air pollution research.

    PubMed Central

    Delfino, Ralph J

    2002-01-01

    Outdoor ambient air pollutant exposures in communities are relevant to the acute exacerbation and possibly the onset of asthma. However, the complexity of pollutant mixtures and etiologic heterogeneity of asthma has made it difficult to identify causal components in those mixtures. Occupational exposures associated with asthma may yield clues to causal components in ambient air pollution because such exposures are often identifiable as single-chemical agents (e.g., metal compounds). However, translating occupational to community exposure-response relationships is limited. Of the air toxics found to cause occupational asthma, only formaldehyde has been frequently investigated in epidemiologic studies of allergic respiratory responses to indoor air, where general consistency can be shown despite lower ambient exposures. The specific volatile organic compounds (VOCs) identified in association with occupational asthma are generally not the same as those in studies showing respiratory effects of VOC mixtures on nonoccupational adult and pediatric asthma. In addition, experimental evidence indicates that airborne polycyclic aromatic hydrocarbon (PAH) exposures linked to diesel exhaust particles (DEPs) have proinflammatory effects on airways, but there is insufficient supporting evidence from the occupational literature of effects of DEPs on asthma or lung function. In contrast, nonoccupational epidemiologic studies have frequently shown associations between allergic responses or asthma with exposures to ambient air pollutant mixtures with PAH components, including black smoke, high home or school traffic density (particularly truck traffic), and environmental tobacco smoke. Other particle-phase and gaseous co-pollutants are likely causal in these associations as well. Epidemiologic research on the relationship of both asthma onset and exacerbation to air pollution is needed to disentangle effects of air toxics from monitored criteria air pollutants such as particle mass

  10. Temporal and modal characterization of DoD source air toxic ...

    EPA Pesticide Factsheets

    This project tested three, real-/near real-time monitoring techniques to develop air toxic emission factors for Department of Defense (DoD) platform sources. These techniques included: resonance enhanced multi photon ionization time of flight mass spectrometry (REMPI-TOFMS) for organic air toxics, laser induced breakdown spectroscopy (LIBS) for metallic air toxics, and optical remote sensing (ORS) methods for measurement of criteria pollutants and other hazardous air pollutants (HAPs). Conventional emission measurements were used for verification of the real-time monitoring results. The REMPI-TOFMS system was demonstrated on the following: --a United States U.S. Marine Corps (USMC) diesel generator, --a U.S. Air Force auxiliary power unit (APU), --the waste combustor at the Portsmouth Naval Shipyard, during a multi-monitor environmental technology verification (ETV) test for dioxin monitoring systems, --two dynamometer-driven high mobility multi-purpose wheeled vehicles (HMMWVs), --an idling Abrams battle tank, --a Bradley infantry fighting vehicle (IFV), and --an F-15 and multiple F-22 U.S. Air Force aircraft engines. LIBS was tested and applied solely to the U.S. Marine Corps diesel generator. The high detection limits of LIBS for toxic metals limited its usefulness as a real time analyzer for most DoD sources. ORS was tested only on the APU with satisfactory results for non-condensable combustion products (carbon monoxide [CO], carbon dioxide

  11. EXTRAN: A computer code for estimating concentrations of toxic substances at control room air intakes

    SciTech Connect

    Ramsdell, J.V.

    1991-03-01

    This report presents the NRC staff with a tool for assessing the potential effects of accidental releases of radioactive materials and toxic substances on habitability of nuclear facility control rooms. The tool is a computer code that estimates concentrations at nuclear facility control room air intakes given information about the release and the environmental conditions. The name of the computer code is EXTRAN. EXTRAN combines procedures for estimating the amount of airborne material, a Gaussian puff dispersion model, and the most recent algorithms for estimating diffusion coefficients in building wakes. It is a modular computer code, written in FORTRAN-77, that runs on personal computers. It uses a math coprocessor, if present, but does not require one. Code output may be directed to a printer or disk files. 25 refs., 8 figs., 4 tabs.

  12. Formaldehyde: a candidate toxic air contaminant. Final report

    SciTech Connect

    Frye, B.; Parker, T.

    1988-03-01

    Formaldehyde (HCHO) is a gas widely used in adhesives and resins, textiles, embalming fluids, fungicides, air fresheners, and cosmetics. It is directly emitted into the ambient outdoor air from vehicular and stationary sources, and is also produced in the atmosphere from other substances by photochemical smog processes. The International Agency for Research on Cancer (IARC) has determined that there is sufficient evidence for carcinogenicity of formaldehyde to animals, and limited evidence for carcinogenicity to humans. EPA classifies formaldehyde as a probable human carcinogen with a one in a million risk concentration of 0.08 ppb.

  13. National air toxics information clearinghouse: Bibliography of selected reports and federal register notices related to air toxics. Volume 6. Citations, 1992. Final report

    SciTech Connect

    Not Available

    1992-07-01

    The purpose of the report is to provide State and local agencies with citations of reports and Federal Register notices useful in developing and operating air toxics control programs. The reports selected for the bibliography were published by the following agencies: EPA, NAS, NCI, NIEHS, NTP, NIOSH, ATSDR, CPSC, WHO, and IARC. Relevant reports published by various State and local agencies are also included in the edition. The citations selected this year were compiled from sources available through January 31, 1992.

  14. National Air Toxics Information Clearinghouse: Bibliography of selected reports and Federal Register notices related to air toxics. Index, 1990. Final report

    SciTech Connect

    Owen, C.A.; Cooper, L.Y.; Norris, C.E.

    1990-07-01

    The purpose of the report is to provide State and local agencies with citations of reports of Federal Register notices useful in developing and operating air toxics control programs. The reports selected for the bibliography were published by the following agencies: EPA, NAS, NCI, NIEHS, NTP, NIOSH, ATSDR, CPSC, WHO, and IARC. Relevant reports published by various State and local agencies are also included in the edition. The citations selected this year were compiled from sources available through January 31, 1990.

  15. National Air Toxics Information Clearinghouse: Bibliography of selected reports and Federal Register notices related to air toxics. Volume 4. Citations, 1990. Final report

    SciTech Connect

    Owen, C.A.; Cooper, L.Y.; Norris, C.E.

    1990-07-01

    The purpose of the report is to provide State and local agencies with citations of reports and Federal Register notices useful in developing and operating air toxics control programs. The reports selected for the bibliography were published by the following agencies: EPA, NAS, NCI, NIEHS, NTP, NIOSH, ATSDR, CPSC, WHO, and IARC. Relevant reports published by various State and local agencies are also included in this edition. The citations selected this year were compiled from sources available through January 31, 1990.

  16. MEASUREMENT OF LOW LEVEL AIR TOXICS WITH MODIFIED UV DOAS

    EPA Science Inventory

    To further understand near source impacts, EPA is working to develop open-path optical techniques for spatiotemporal-resolved measurement of air pollutants. Of particular interest is near real time quantification of mobile-source generated CO, Nox and hydrocarbons measured in cl...

  17. FINE SCALE AIR QUALITY MODELING USING DISPERSION AND CMAQ MODELING APPROACHES: AN EXAMPLE APPLICATION IN WILMINGTON, DE

    EPA Science Inventory

    Characterization of spatial variability of air pollutants in an urban setting at fine scales is critical for improved air toxics exposure assessments, for model evaluation studies and also for air quality regulatory applications. For this study, we investigate an approach that su...

  18. Concentrations, sources and human health risk of inhalation exposure to air toxics in Edmonton, Canada.

    PubMed

    Bari, Md Aynul; Kindzierski, Warren B

    2017-04-01

    With concern about levels of air pollutants in recent years in the Capital Region of Alberta, an investigation of ambient concentrations, sources and potential human health risk of hazardous air pollutants (HAPs) or air toxics was undertaken in the City of Edmonton over a 5-year period (2009-2013). Mean concentrations of individual HAPs in ambient air including volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) and trace metals ranged from 0.04 to 1.73 μg/m(3), 0.01-0.54 ng/m(3), and 0.05-3.58 ng/m(3), respectively. Concentrations of benzene, naphthalene, benzo(a)pyrene (BaP), arsenic, manganese and nickel were far below respective annual Alberta Ambient Air Quality Objectives. Carcinogenic and non-carcinogenic risk of air toxics were also compared with risk levels recommended by regulatory agencies. Positive matrix factorization identified six air toxics sources with traffic as the dominant contributor to total HAPs (4.33 μg/m(3), 42%), followed by background/secondary organic aerosol (SOA) (1.92 μg/m(3), 25%), fossil fuel combustion (0.92 μg/m(3), 11%). On high particulate air pollution event days, local traffic was identified as the major contributor to total HAPs compared to background/SOA and fossil fuel combustion. Carcinogenic risk values of traffic, background/SOA and metals industry emissions were above the USEPA acceptable level (1 × 10(-6)), but below a tolerable risk (1 × 10(-4)) and Alberta benchmark (1 × 10(-5)). These findings offer useful preliminary information about current ambient air toxics levels, dominant sources and their potential risk to public health; and this information can support policy makers in the development of appropriate control strategies if required.

  19. Acute toxicity bioassays of mercuric chloride and malathion on air-breathing fish Channa punctatus (Bloch).

    PubMed

    Pandey, Sanjay; Kumar, Ravindra; Sharma, Shilpi; Nagpure, N S; Srivastava, Satish K; Verma, M S

    2005-05-01

    Acute toxicity tests (96 h) were conducted in flow-through systems to determine the lethal toxicity of a heavy metal compound, mercuric chloride, and an organophosphorus pesticide, malathion, to air-breathing teleost fish, Channa punctatus (Bloch) and to study their behavior. The 96-h LC50 values were determined, as well as safe levels. The results indicate that mercuric chloride is more toxic than malathion to the fish species under study. Dose- and dose-time-dependent increases in mortality rate were also observed in response to both test chemicals.

  20. Bioluminescent liquid light guide pad biosensor for indoor air toxicity monitoring.

    PubMed

    Eltzov, Evgeni; Cohen, Avital; Marks, Robert S

    2015-04-07

    Indoor air pollution became a recent concern found to be oftentimes worse than outdoor air quality. We developed a tool that is cheap and simple and enables continuous monitoring of air toxicity. It is a biosensor with both a nondisposable (monitor) and disposable (calcium alginate pads with immobilized bacteria) elements. Various parameters to enhance its signal have been tested (including the effect of the pad's orientation, it's exposure to either temperature or time with the air toxicant analyte, and various concentrations thereof). Lastly, the sensor has demonstrated its ability to sense the presence of chemicals in a real, indoor environment. This is the first step in the creation of a sensitive and simple operative tool that may be used in different indoor environments.

  1. AIR QUALITY MODELING OF HAZARDOUS POLLUTANTS: CURRENT STATUS AND FUTURE DIRECTIONS

    EPA Science Inventory

    The paper presents a review of current air toxics modeling applications and discusses possible advanced approaches. Many applications require the ability to predict hot spots from industrial sources or large roadways that are needed for community health and Environmental Justice...

  2. Risk of leukemia in relation to exposure to ambient air toxics in pregnancy and early childhood

    PubMed Central

    Heck, Julia E; Park, Andrew S; Qiu, Jiaheng; Cockburn, Myles; Ritz, Beate

    2014-01-01

    There are few established causes of leukemia, the most common type of cancer in children. Studies in adults suggest a role for specific environmental agents, but little is known about any effect from exposures in pregnancy to toxics in ambient air. In our case-control study, we ascertained 69 cases of acute lymphoblastic leukemia (ALL) and 46 cases of acute myeloid leukemia (AML) from California Cancer Registry records of children < age 6, and 19,209 controls from California birth records within 2km (1.3 miles) (ALL) and 6km (3.8 miles) (AML) of an air toxics monitoring station between 1990–2007. Information on air toxics exposures was taken from community air monitors. We used logistic regression to estimate the risk of leukemia associated with one interquartile range increase in air toxic exposure. Risk of ALL was elevated with 3rd trimester exposure to polycyclic aromatic hydrocarbons (OR=1.16, 95%CI 1.04, 1.29), arsenic (OR=1.33, 95%CI 1.02, 1.73), benzene (OR=1.50, 95%CI 1.08, 2.09), and three other toxics related to fuel combustion. Risk of AML was increased with 3rd trimester exposure to chloroform (OR=1.30, 95%CI 1.00, 1.69), benzene (1.75, 95%CI 1.04, 2.93), and two other traffic-related toxics. During the child’s first year, exposure to butadiene, ortho-xylene, and toluene increased risk for AML and exposure to selenium increased risk for ALL. Benzene is an established cause of leukemia in adults; this study supports that ambient exposures to this and other chemicals in pregnancy and early life may also increase leukemia risk in children. PMID:24472648

  3. High time-resolved measurements of organic air toxics in different source regimes

    NASA Astrophysics Data System (ADS)

    Logue, J. M.; Huff-Hartz, K. E.; Lambe, A. T.; Donahue, N. M.; Robinson, A. L.

    2009-12-01

    High time-resolved (HTR) measurements can provide significant insight into sources and exposures of air pollution. In this study, an automated instrument was developed and deployed to measure hourly concentrations of 18 gas-phase organic air toxics and 6 volatile organic compounds (VOCs) at three sites in and around Pittsburgh, Pennsylvania. The sites represent different source regimes: a site with substantial mobile-source emissions; a residential site adjacent to a heavily industrialized zone; and an urban background site. Despite the close proximity of the sites (less than 13 km apart), the temporal characteristic of outdoor concentrations varied widely. Most of the compounds measured were characterized by short periods of elevated concentrations or plume events, but the duration, magnitude and composition of these events varied from site to site. The HTR data underscored the strong role of emissions from local sources on exposure to most air toxics. Plume events contributed more than 50% of the study average concentrations for all pollutants except chloroform, 1,2-dichloroethane, and carbon tetrachloride. Wind directional dependence of air toxic concentrations revealed that emissions from large industrial facilities affected concentrations at all of the sites. Diurnal patterns and weekend/weekday variations indicated the effects of the mixing layer, point source emissions patterns, and mobile source air toxics (MSATs) on concentrations. Concentrations of many air toxics were temporally correlated, especially MSATs, indicating that they are likely co-emitted. It was also shown that correlations of the HTR data were greater than lower time resolution data (24-h measurements). This difference was most pronounced for the chlorinated pollutants. The stronger correlations in HTR measurements underscore their value for source apportionment studies.

  4. Personal and ambient exposures to air toxics in Camden, New Jersey.

    PubMed

    Lioy, Paul J; Fan, Zhihua; Zhang, Junfeng; Georgopoulos, Panos; Wang, Sheng-Wei; Ohman-Strickland, Pamela; Wu, Xiangmei; Zhu, Xianlei; Harrington, Jason; Tang, Xiaogang; Meng, Qingyu; Jung, Kyung Hwa; Kwon, Jaymin; Hernandez, Marta; Bonnano, Linda; Held, Joann; Neal, John

    2011-08-01

    Personal exposures and ambient concentrations of air toxics were characterized in a pollution "hot spot" and an urban reference site, both in Camden, New Jersey. The hot spot was the city's Waterfront South neighborhood; the reference site was a neighborhood, about 1 km to the east, around the intersection of Copewood and Davis streets. Using personal exposure measurements, residential ambient air measurements, statistical analyses, and exposure modeling, we examined the impact of local industrial and mobile pollution sources, particularly diesel trucks, on personal exposures and ambient concentrations in the two neighborhoods. Presented in the report are details of our study design, sample and data collection methods, data- and model-analysis approaches, and results and key findings of the study. In summary, 107 participants were recruited from nonsmoking households, including 54 from Waterfront South and 53 from the Copewood-Davis area. Personal air samples were collected for 24 hr and measured for 32 target compounds--11 volatile organic compounds (VOCs*), four aldehydes, 16 polycyclic aromatic hydrocarbons (PAHs), and particulate matter (PM) with an aerodynamic diameter < or = 2.5 microm (PM2.5). Simultaneously with the personal monitoring, ambient concentrations of the target compounds were measured at two fixed monitoring sites, one each in the Waterfront South and Copewood-Davis neighborhoods. To understand the potential impact of local sources of air toxics on personal exposures caused by temporal (weekdays versus weekend days) and seasonal (summer versus winter) variations in source intensities of the air toxics, four measurements were made of each subject, two in summer and two in winter. Within each season, one measurement was made on a weekday and the other on a weekend day. A baseline questionnaire and a time diary with an activity questionnaire were administered to each participant in order to obtain information that could be used to understand

  5. Air toxic emissions from the combustion of coal: Identifying and quantifying hazardous air pollutants from US coals

    SciTech Connect

    Szpunar, C.B.

    1992-09-01

    This report addresses the key air toxic emissions likely to emanate from continued and expanded use of domestic coal. It identifies and quantifies those trace elements specified in the US 1990 Clean Air Act Amendments, by tabulating selected characterization data on various source coals by region, state, and rank. On the basis of measurements by various researchers, this report also identifies those organic compounds likely to be derived from the coal combustion process (although their formation is highly dependent on specific boiler configurations and operating conditions).

  6. Temporal and modal characterization of DoD source air toxic emission factors: final report

    EPA Science Inventory

    This project tested three, real-/near real-time monitoring techniques to develop air toxic emission factors for Department of Defense (DoD) platform sources. These techniques included: resonance enhanced multi photon ionization time of flight mass spectrometry (REMPI-TOFMS) for o...

  7. Evaluation of air toxic emissions from advanced and conventional coal-fired power plants

    SciTech Connect

    Chu, P.; Epstein, M.; Gould, L.; Botros, P.

    1995-12-31

    This paper evaluates the air toxics measurements at three advanced power systems and a base case conventional fossil fuel power plant. The four plants tested include a pressurized fluidized bed combustor, integrated gasification combined cycle, circulating fluidized bed combustor, and a conventional coal-fired plant.

  8. CORONA DESTRUCTION: AN INNOVATIVE CONTROL TECHNOLOGY FOR VOCS AND AIR TOXICS

    EPA Science Inventory

    This paper discusses the work and results to date leading to the demonstration of the corona destruction process at pilot scale. The research effort in corona destruction of volatile organic compounds (VOCs) and air toxics has shown significant promise for providing a valuable co...

  9. APPLICATIONS ANALYSIS REPORT: TOXIC TREATMENTS, IN-SITU STEAM/HOT-AIR STRIPPING TECHNOLOGY

    EPA Science Inventory

    This document is an evaluation of the performance of the Toxic Treatments (USA), Inc., (TTUSA) in situ steam/hot-air stripping technology and its applicability as an on-site treatment technique for hazardous waste site soil cleanup of volatile and semivolatile contaminants. Both ...

  10. EMISSIONS OF AIR TOXICS FROM A SIMULATED CHARCOAL KILN EQUIPPED WITH AN AFTERBURNER

    EPA Science Inventory

    The report discusses emissions of air toxics from a simulated charcoal kiln equipped with an afterburner. A laboratory-scale simulator was constructed and tested to determine if it could be used to produce charcoal that was similar to that produced in Missouri-type charcoal kilns...

  11. DETERMINANTS OF HUMAN EXPOSURES TO AIR TOXICS AND ASSOCIATED HEALTH EFFECTS

    EPA Science Inventory

    Individuals are exposed to wide variety of air toxics in various indoor and outdoor microenvironments during the course of their daily activities. Sources of emissions include a wide variety of indoor and outdoor sources, including stationary and mobile sources, building material...

  12. CRITERIA AND AIR TOXIC EMISSIONS FROM IN-USE, LOW EMISSION VEHICLES (LEVS)

    EPA Science Inventory

    The U.S. Environmental Protection Agency implemented a program to identify tailpipe emissions of criteria and air toxic contaminants from in-use, light-duty Low Emission Vehicles (LEVs). EPA recruited twenty-five LEVs in 2002, and measured emissions on a chassis dynamometer usin...

  13. Water quality-based toxics evaluation of Reconquista River, Province of Buenos Aires, Argentina

    SciTech Connect

    Herkovits, J.; Herkovits, F.D.; Perez-Coll, C.S.

    1995-12-31

    The water quality based toxics control is essential to evaluate the aggregate toxicity, bioavailability as well as for the detection and/or prediction of ecological impacts. Reconquista River valley is situated in the north area of Great Buenos Aires with a population of three million inhabitants. The river is loaded with industrial and municipal waste water. In the present preliminary study the authors report the toxicity found in surface water at a 6 sample stations (including a reference point and a stream) all of them downstream from mixing zone areas. The ecotoxicological study was performed with three native species (Bufo arenarum embryos, Cnesterodon decemmaculatus and a species of shrimp collected in an upstream reference site) during a 7 day renewal toxicity test conducted with 10 individuals (by duplicate) for each condition plus control. The results point out that the Bufo arenarum embryos test is the most sensitive to toxic substances as well as the better adapted species to the changing physico-chemical conditions of this river. The results obtained with embryos, expressed in Acute and Chronic Toxicity Units (according USEPA) range between <0.3--2 and <1--5 respectively (recommended magnitudes for industrial effluents according USEPA: 0.3 and 1 toxicity units respectively). Therefore, the toxicity found in Reconquista River ecosystem was up to 6 times higher than the maximal value recommended for industrial effluents. It is noteworthy that in the place where toxicity starts to rise, a large number of dead fishes were found and from that place downstream, no macroorganisms were found in the river. The results confirm the high sensitivity of Bufo arenarum embryos for continental waters ecotoxicological studies and the possibility of using this test as a short-term chronic toxicity method for water quality-based toxics control.

  14. Air toxics being measured more accurately, controlled more effectively

    SciTech Connect

    1995-04-01

    In response to the directives of the Clean Air Act Amendments, Argonne National Laboratory is developing new or improved pollutant control technologies for industries that burn fossil fuels. This research continues Argonne`s traditional support for the US DOE Flue Gas Cleanup Program. Research is underway to measure process emissions and identify new and improved control measures. Argonne`s emission control research has ranged from experiments in the basic chemistry of pollution-control systems, through laboratory-scale process development and testing to pilot-scale field tests of several technologies. Whenever appropriate, the work has emphasized integrated or combined control systems as the best approach to technologies that offer low cost and good operating characteristics.

  15. STRUCTURE-ACTIVITY APPROACHES AND DATA EXPLORATION TOOLS FOR PRIORITIZING AND ASSESSING THE TOXICITY OF HAZARDOUS AIR POLLUTANTS

    EPA Science Inventory


    STRUCTURE-ACTIVITY APPROACHES AND DATA EXPLORATION TOOLS FOR PRIORITIZING AND ASSESSING THE TOXICITY OF HAZARDOUS AIR POLLUTANTS

    Hazardous Air Pollutants (HAPs) refers to a set of structurally diverse environmental chemicals, many with limited toxicity data, that have...

  16. Assessment of Sociodemographic and Geographic Disparities in Cancer Risk from Air Toxics in South Carolina

    PubMed Central

    Wilson, Sacoby; Burwell-Naney, Kristen; Jiang, Chengsheng; Zhang, Hongmei; Samantapudi, Ashok; Murray, Rianna; Dalemarre, Laura; Rice, LaShanta; Williams, Edith

    2015-01-01

    Populations of color and low-income communities are often disproportionately burdened by exposures to various environmental contaminants, including air pollution. Some air pollutants have carcinogenic properties that are particularly problematic in South Carolina (SC), a state that consistently has high rates of cancer mortality for all sites. The purpose of this study was to assess cancer risk disparities in SC by linking risk estimates from the U.S. Environmental Protection Agency’s 2005 National Air Toxics Assessment (NATA) with sociodemographic data from the 2000 US Census Bureau. Specifically, NATA risk data for varying risk categories were linked by tract ID and analyzed with sociodemographic variables from the 2000 census using R. The average change in cancer risk from all sources by sociodemographic variable was quantified using multiple linear regression models. Spatial methods were further employed using ArcGIS 10 to assess the distribution of all source risk and percent non-white at each census tract level. The relative risk estimates of the proportion of high cancer risk tracts (defined as the top 10% of cancer risk in SC) and their respective 95% confidence intervals (CIs) were calculated between the first and latter three quartiles defined by sociodemographic factors, while the variance in the percentage of high cancer risk between quartile groups was tested using Pearson’s chi-square. The average total cancer risk for SC was 26.8 people/million (ppl/million). The risk from on-road sources was approximately 5.8 ppl/million, higher than the risk from major, area, and non-road sources (1.8, 2.6, and 1.3 ppl/million), respectively. Based on our findings, addressing on-road sources may decrease the disproportionate cancer risk burden among low-income populations and communities of color in SC. PMID:26037107

  17. 40 CFR Table 5 to Subpart Mmmm of... - Model Rule-Toxic Equivalency Factors

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 7 2013-07-01 2013-07-01 false Model Rule-Toxic Equivalency Factors 5 Table 5 to Subpart MMMM of Part 60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Emission Guidelines and Compliance Times for Existing Sewage...

  18. 40 CFR Table 5 to Subpart Mmmm of... - Model Rule-Toxic Equivalency Factors

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Model Rule-Toxic Equivalency Factors 5 Table 5 to Subpart MMMM of Part 60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Emission Guidelines and Compliance Times for Existing Sewage...

  19. Characterization of air toxics from oil-fired firetube boiler

    SciTech Connect

    Miller, C.A.; Ryan, J.V.; Lombardo, T.

    1996-08-01

    Tests were conducted on a commercially available firetube package boiler running on No. 2 through No. 6 oils to determine the emissions levels of hazardous air pollutants from the combustion of four fuel oils. Measurements of carbon monoxide, nitrogen oxides, particulate matter, and sulfur dioxide stack gas concentrations were made for each oil. Flue gases were also sampled to determine levels of volatile and semivolatile organic compounds and of metals. Analytical procedures were used to provide more detailed information regarding the emissions rates for carbonyls (aldehydes and ketones), and polycyclic aromatic hydrocarbons (PAHs) in addition to the standard analyses for volatile and semivolatile organics. Metals emissions were greater than organic emissions for all oils tested, by an order of magnitude. Carbonyls dominated the organic emissions, with emission rates more than double the remaining organics for all four oils tested. Formaldehyde made up the largest percentage of carbonyls, at roughly 50% of these emissions for three of the four oils, and approximately 30% of the carbonyl emissions from the low sulfur No. 6 oil. Naphthalene was found to be the largest part of the PAH emissions for three of the four oils, with phenanthrene being greatest for the No. 2 fuel oil. The flue gases were also sampled for polychlorinated dibenzodioxins and polychlorinated dibenzofurans. 9 refs., 4 figs., 8 tabs.

  20. SAR STUDY OF NASAL TOXICITY: LESSONS FOR MODELING SMALL TOXICITY DATASETS

    EPA Science Inventory

    Most toxicity data, particularly from whole animal bioassays, are generated without the needs or capabilities of structure-activity relationship (SAR) modeling in mind. Some toxicity endpoints have been of sufficient regulatory concern to warrant large scale testing efforts (e.g....

  1. Excretory nitrogen metabolism and defence against ammonia toxicity in air-breathing fishes.

    PubMed

    Chew, S F; Ip, Y K

    2014-03-01

    With the development of air-breathing capabilities, some fishes can emerge from water, make excursions onto land or even burrow into mud during droughts. Air-breathing fishes have modified gill morphology and morphometry and accessory breathing organs, which would tend to reduce branchial ammonia excretion. As ammonia is toxic, air-breathing fishes, especially amphibious ones, are equipped with various strategies to ameliorate ammonia toxicity during emersion or ammonia exposure. These strategies can be categorized into (1) enhancement of ammonia excretion and reduction of ammonia entry, (2) conversion of ammonia to a less toxic product for accumulation and subsequent excretion, (3) reduction of ammonia production and avoidance of ammonia accumulation and (4) tolerance of ammonia at cellular and tissue levels. Active ammonia excretion, operating in conjunction with lowering of ambient pH and reduction in branchial and cutaneous NH₃ permeability, is theoretically the most effective strategy to maintain low internal ammonia concentrations. NH₃ volatilization involves the alkalization of certain epithelial surfaces and requires mechanisms to prevent NH₃ back flux. Urea synthesis is an energy-intensive process and hence uncommon among air-breathing teleosts. Aestivating African lungfishes detoxify ammonia to urea and the accumulated urea is excreted following arousal. Reduction in ammonia production is achieved in some air-breathing fishes through suppression of amino acid catabolism and proteolysis, or through partial amino acid catabolism leading to alanine formation. Others can slow down ammonia accumulation through increased glutamine synthesis in the liver and muscle. Yet, some others develop high tolerance of ammonia at cellular and tissue levels, including tissues in the brain. In summary, the responses of air-breathing fishes to ameliorate ammonia toxicity are many and varied, determined by the behaviour of the species and the nature of the environment in

  2. Air pollution modeling and its application III

    SciTech Connect

    De Wispelaere, C.

    1984-01-01

    This book focuses on the Lagrangian modeling of air pollution. Modeling cooling tower and power plant plumes, modeling the dispersion of heavy gases, remote sensing as a tool for air pollution modeling, dispersion modeling including photochemistry, and the evaluation of model performances in practical applications are discussed. Specific topics considered include dispersion in the convective boundary layer, the application of personal computers to Lagrangian modeling, the dynamic interaction of cooling tower and stack plumes, the diffusion of heavy gases, correlation spectrometry as a tool for mesoscale air pollution modeling, Doppler acoustic sounding, tetroon flights, photochemical air quality simulation modeling, acid deposition of photochemical oxidation products, atmospheric diffusion modeling, applications of an integral plume rise model, and the estimation of diffuse hydrocarbon leakages from petrochemical factories. This volume constitutes the proceedings of the Thirteenth International Technical Meeting on Air Pollution Modeling and Its Application held in France in 1982.

  3. Assessing the toxic effects of ethylene glycol ethers using Quantitative Structure Toxicity Relationship models

    SciTech Connect

    Ruiz, Patricia; Mumtaz, Moiz; Gombar, Vijay

    2011-07-15

    Experimental determination of toxicity profiles consumes a great deal of time, money, and other resources. Consequently, businesses, societies, and regulators strive for reliable alternatives such as Quantitative Structure Toxicity Relationship (QSTR) models to fill gaps in toxicity profiles of compounds of concern to human health. The use of glycol ethers and their health effects have recently attracted the attention of international organizations such as the World Health Organization (WHO). The board members of Concise International Chemical Assessment Documents (CICAD) recently identified inadequate testing as well as gaps in toxicity profiles of ethylene glycol mono-n-alkyl ethers (EGEs). The CICAD board requested the ATSDR Computational Toxicology and Methods Development Laboratory to conduct QSTR assessments of certain specific toxicity endpoints for these chemicals. In order to evaluate the potential health effects of EGEs, CICAD proposed a critical QSTR analysis of the mutagenicity, carcinogenicity, and developmental effects of EGEs and other selected chemicals. We report here results of the application of QSTRs to assess rodent carcinogenicity, mutagenicity, and developmental toxicity of four EGEs: 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, and 2-butoxyethanol and their metabolites. Neither mutagenicity nor carcinogenicity is indicated for the parent compounds, but these compounds are predicted to be developmental toxicants. The predicted toxicity effects were subjected to reverse QSTR (rQSTR) analysis to identify structural attributes that may be the main drivers of the developmental toxicity potential of these compounds.

  4. Development of a general baseline toxicity QSAR model for the fish embryo acute toxicity test.

    PubMed

    Klüver, Nils; Vogs, Carolina; Altenburger, Rolf; Escher, Beate I; Scholz, Stefan

    2016-12-01

    Fish embryos have become a popular model in ecotoxicology and toxicology. The fish embryo acute toxicity test (FET) with the zebrafish embryo was recently adopted by the OECD as technical guideline TG 236 and a large database of concentrations causing 50% lethality (LC50) is available in the literature. Quantitative Structure-Activity Relationships (QSARs) of baseline toxicity (also called narcosis) are helpful to estimate the minimum toxicity of chemicals to be tested and to identify excess toxicity in existing data sets. Here, we analyzed an existing fish embryo toxicity database and established a QSAR for fish embryo LC50 using chemicals that were independently classified to act according to the non-specific mode of action of baseline toxicity. The octanol-water partition coefficient Kow is commonly applied to discriminate between non-polar and polar narcotics. Replacing the Kow by the liposome-water partition coefficient Klipw yielded a common QSAR for polar and non-polar baseline toxicants. This developed baseline toxicity QSAR was applied to compare the final mode of action (MOA) assignment of 132 chemicals. Further, we included the analysis of internal lethal concentration (ILC50) and chemical activity (La50) as complementary approaches to evaluate the robustness of the FET baseline toxicity. The analysis of the FET dataset revealed that specifically acting and reactive chemicals converged towards the baseline toxicity QSAR with increasing hydrophobicity. The developed FET baseline toxicity QSAR can be used to identify specifically acting or reactive compounds by determination of the toxic ratio and in combination with appropriate endpoints to infer the MOA for chemicals.

  5. Exposure information in environmental health research: Current opportunities and future directions for particulate matter, ozone, and toxic air pollutants

    SciTech Connect

    McKone, Thomas E.; Ryan, P. Barry; Ozkaynak, Haluk

    2007-02-01

    Understanding and quantifying outdoor and indoor sources of human exposure are essential but often not adequately addressed in health-effects studies for air pollution. Air pollution epidemiology, risk assessment, health tracking and accountability assessments are examples of health-effects studies that require but often lack adequate exposure information. Recent advances in exposure modeling along with better information on time-activity and exposure factors data provide us with unique opportunities to improve the assignment of exposures for both future and ongoing studies linking air pollution to health impacts. In September 2006, scientists from the US Environmental Protection Agency (EPA) and the Centers for Disease Control and Prevention (CDC) along with scientists from the academic community and state health departments convened a symposium on air pollution exposure and health in order to identify, evaluate, and improve current approaches for linking air pollution exposures to disease. This manuscript presents the key issues, challenges and recommendations identified by the exposure working group, who used cases studies of particulate matter, ozone, and toxic air pollutant exposure to evaluate health-effects for air pollution. One of the over-arching lessons of this workshop is that obtaining better exposure information for these different health-effects studies requires both goal-setting for what is needed and mapping out the transition pathway from current capabilities to meeting these goals. Meeting our long-term goals requires definition of incremental steps that provide useful information for the interim and move us toward our long-term goals. Another over-arching theme among the three different pollutants and the different health study approaches is the need for integration among alternate exposure assessment approaches. For example, different groups may advocate exposure indicators, biomonitoring, mapping methods (GIS), modeling, environmental media

  6. Exposure information in environmental health research: current opportunities and future directions for particulate matter, ozone, and toxic air pollutants.

    PubMed

    McKone, Thomas E; Ryan, P Barry; Ozkaynak, Halûk

    2009-01-01

    Understanding and quantifying outdoor and indoor sources of human exposure are essential but often not adequately addressed in health effect studies for air pollution. Air pollution epidemiology, risk assessment, health tracking, and accountability assessments are examples of health effect studies that require but often lack adequate exposure information. Recent advances in exposure modeling along with better information on time-activity and exposure factor data provide us with unique opportunities to improve the assignment of exposures for both future and ongoing studies linking air pollution to health impacts. In September 2006, scientists from the US Environmental Protection Agency and the Centers for Disease Control and Prevention along with scientists from the academic community and state health departments convened a symposium on air pollution exposure and health to identify, evaluate, and improve current approaches for linking air pollution exposures to disease. This manuscript presents the key issues, challenges, and recommendations identified by the exposure working group, who used case studies of particulate matter, ozone, and toxic air-pollutant exposure to evaluate health effects for air pollution. One of the overarching lessons of this workshop is that obtaining better exposure information for these different health effect studies requires both goal setting for what is needed and mapping out the transition pathway from current capabilities for meeting these goals. Meeting our long-term goals requires definition of incremental steps that provide useful information for the interim and move us toward our long-term goals. Another overarching theme among the three different pollutants and the different health study approaches is the need for integration among alternate exposure-assessment approaches. For example, different groups may advocate exposure indicators, biomonitoring, mapping methods (GIS), modeling, environmental media monitoring, and/or personal

  7. Residential exposure to air toxics is linked to lower grade point averages among school children in El Paso, Texas, USA

    PubMed Central

    Clark-Reyna, Stephanie E.; Grineski, Sara E.; Collins, Timothy W.

    2015-01-01

    Children in low-income neighborhoods tend to be disproportionately exposed to environmental toxicants. This is cause for concern because exposure to environmental toxicants negatively affect health, which can impair academic success. To date, it is unknown if associations between air toxics and academic performance found in previous school-level studies persist when studying individual children. In pairing the National Air Toxics Assessment (NATA) risk estimates for respiratory and diesel particulate matter risk disaggregated by source, with individual-level data collected through a mail survey, this paper examines the effects of exposure to residential environmental toxics on academic performance for individual children for the first time and adjusts for school-level effects using generalized estimating equations. We find that higher levels of residential air toxics, especially those from non-road mobile sources, are statistically significantly associated with lower grade point averages among fourth and fifth grade school children in El Paso (Texas, USA). PMID:27034529

  8. 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.

  9. Major ion toxicity of six produced waters to three freshwater species: Application of ion toxicity models and TIE procedures

    SciTech Connect

    Tietge, J.E.; Hockett, J.R.; Evans, J.M.

    1997-10-01

    Previous research to characterize the acute toxicity of major ions to freshwater organisms resulted in the development of statistical toxicity models for three freshwater species (Ceriodaphnia dubia, Pimephales promelas, and Daphnia magna). These ion toxicity models estimate the toxicity of seven major ions utilizing logistic regression. In this study, the ion toxicity models were used in conjunction with Phase 1 toxicity identification evaluation (TIE) procedures to evaluate the contribution of major ion toxicity to the total toxicity of six produced water samples ranging in total salinity from 1.7 to 58.1 g/L. Initial toxicities of all six samples were compared to the model predictions. Four produced waters were found to have toxicity consistent with toxicity attributable to major ion concentrations only. Two produced waters were found to exhibit more toxicity than expected from ion concentrations alone. These samples were subjected to Phase 1 TIE procedures. Toxicities were reduced by specific Phase 1 TIE manipulations to those predicted by the ion toxicity models. Mock effluents were used to verify the results. The combination of the ion toxicity models with Phase 1 TIE procedures successfully quantified the toxicity due to major ions in six produced water samples.

  10. Evaluation of a possible association of urban air toxics and asthma.

    PubMed Central

    Leikauf, G D; Kline, S; Albert, R E; Baxter, C S; Bernstein, D I; Buncher, C R

    1995-01-01

    The prevalence of asthma, measured either as the frequency of hospital admissions or number of deaths attributed to asthma, has increased over the last 15 to 20 years. Rapid increases in disease prevalence are more likely to be attributable to environmental than genetic factors. Inferring from past associations between air pollution and asthma, it is feasible that changes in the ambient environment could contribute to this increase in morbidity and mortality. Scientific evaluation of the links between air pollution and the exacerbation of asthma is incomplete, however. Currently, criteria pollutants [SOx, NOx, O3, CO, Pb, particulate matter (PM10)] and other risk factors (exposure to environmental tobacco smoke, volatile organic compounds, etc.) are constantly being evaluated as to their possible contributions to this situation. Data from these studies suggest that increases in respiratory disease are associated with exposures to ambient concentrations of particulate and gaseous pollutants. Similarly, exposure to environmental tobacco smoke, also a mixture of particulate and gaseous air toxics, has been associated with an increase in asthma among children. In addition, current associations of adverse health effects with existing pollution measurements are often noted at concentrations below those that produce effects in controlled animal and human exposures to each pollutant alone. These findings imply that adverse responses are augmented when persons are exposed to irritant mixtures of particles and gases and that current measurements of air pollution are, in part, indirect in that the concentrations of criteria pollutants are acting as surrogates of our exposure to a complex mixture. Other irritant air pollutants, including certain urban air toxics, are associated with asthma in occupational settings and may interact with criteria pollutants in ambient air to exacerbate asthma. An evaluation of dose-response information for urban air toxics and biological

  11. THE IMPACT OF SHRINKING HANFORD BOUNDARIES ON PERMITS FOR TOXIC AIR POLLUTANT EMISSIONS FROM THE HANFORD 200 WEST AREA

    SciTech Connect

    JOHNSON, R.E.

    2005-11-09

    This presentation (CE-580. Graduate Seminar) presents a brief description of an approach to use a simpler dispersion modeling method (SCREEN3) in conjunction with joint frequency tables for Hanford wind conditions to evaluate the impacts of shrinking the Hanford boundaries on the current permits for facilities in the 200 West Area. To fulfill requirements for the graduate student project (CE-702. Master's Special Problems), this evaluation will be completed and published over the next two years. Air toxic emissions play an important role in environmental quality and require a state approved permit. One example relates to containers or waste that are designated as Transuranic Waste (TRU), which are required to have venting devices due to hydrogen generation. The Washington State Department of Ecology (Ecology) determined that the filters used did not meet the definition of a ''pressure relief device'' and that a permit application would have to be submitted by the Central Waste Complex (CWC) for criteria pollutant and toxic air pollutant (TAP) emissions in accordance with Washington Administrative Code (WAC) 173-400 and 173-460. The permit application submitted in 2000 to Ecology used Industrial Source Code III (ISCIII) dispersion modeling to demonstrate that it was not possible for CWC to release a sufficient quantity of fugitive Toxic Air Pollutant emissions that could exceed the Acceptable Source Impact Levels (ASILs) at the Hanford Site Boundary. The modeled emission rates were based on the diurnal breathing in and out through the vented drums (approximately 20% of the drums), using published vapor pressure, molecular weight, and specific gravity data for all 600+ compounds, with a conservative estimate of one exchange volume per day (208 liters per drum). Two permit applications were submitted also to Ecology for the Waste Receiving and Processing Facility and the T Plant Complex. Both permit applications were based on the Central Waste Complex approach, and

  12. “A Reduced-form Model to Estimate Near-road Air Quality for Communities: the Community Line Source modeling system (C-LINE)”

    EPA Science Inventory

    The paper presents the Community Line Source (C-LINE) modeling system that estimates toxic air pollutant (air toxics) concentration gradients within 500 meters of busy roadways for community-sized areas on the order of 100 km2. C-LINE accesses publicly available datasets with nat...

  13. Asthma symptoms in Hispanic children and daily ambient exposures to toxic and criteria air pollutants.

    PubMed Central

    Delfino, Ralph J; Gong, Henry; Linn, William S; Pellizzari, Edo D; Hu, Ye

    2003-01-01

    Although acute adverse effects on asthma have been frequently found for the U.S. Environmental Protection Agency's principal criteria air pollutants, there is little epidemiologic information on specific hydrocarbons from toxic emission sources. We conducted a panel study of 22 Hispanic children with asthma who were 10-16 years old and living in a Los Angeles community with high traffic density. Subjects filled out symptom diaries daily for up to 3 months (November 1999 through January 2000). Pollutants included ambient hourly values of ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide and 24-hr values of volatile organic compounds (VOCs), particulate matter with aerodynamic diameter < 10 microm (PM10, and elemental carbon (EC) and organic carbon (OC) PM10 fractions. Asthma symptom severity was regressed on pollutants using generalized estimating equations, and peak expiratory flow (PEF) was regressed on pollutants using mixed models. We found positive associations of symptoms with criteria air pollutants (O3, NO2, SO2, PM10), EC-OC, and VOCs (benzene, ethylbenzene, formaldehyde, acetaldehyde, acetone, 1,3-butadiene, tetrachloroethylene, toluene, m,p-xylene, and o-xylene). Selected adjusted odds ratios for bothersome or more severe asthma symptoms from interquartile range increases in pollutants were, for 1.4 ppb 8-hr NO2, 1.27 [95% confidence interval (CI), 1.05-1.54]; 1.00 ppb benzene, 1.23 (95% CI, 1.02-1.48); 3.16 ppb formaldehyde, 1.37 (95% CI, 1.04-1.80); 37 microg/m3 PM10, 1.45 (95% CI, 1.11-1.90); 2.91 microg/m3 EC, 1.85 (95% CI, 1.11-3.08); and 4.64 microg/m3 OC, 1.88 (95% CI, 1.12-3.17). Two-pollutant models of EC or OC with PM10 showed little change in odds ratios for EC (to 1.83) or OC (to 1.89), but PM10 decreased from 1.45 to 1.0. There were no significant associations with PEF. Findings support the view that air toxins in the pollutant mix from traffic and industrial sources may have adverse effects on asthma in children. PMID:12676630

  14. [Development of human embryonic stem cell model for toxicity evaluation].

    PubMed

    Yu, Guang-yan; Cao, Tong; Ouyang, Hong-wei; Peng, Shuang-qing; Deng, Xu-liang; Li, Sheng-lin; Liu, He; Zou, Xiao-hui; Fu, Xin; Peng, Hui; Wang, Xiao-ying; Zhan, Yuan

    2013-02-18

    The current international standard for toxicity screening of biomedical devices and materials recommend the use of immortalized cell lines because of their homogeneous morphologies and infinite proliferation which provide good reproducibility for in vitro cytotoxicity screening. However, most of the widely used immortalized cell lines are derived from animals and may not be representative of normal human cell behavior in vivo, in particular in terms of the cytotoxic and genotoxic response. Therefore, It is vital to develop a model for toxicity evaluation. In our studies, two Chinese human embryonic stem cell (hESC) lines as toxicity model were established. hESC derived tissue/organ cell model for tissue/organ specific toxicity evaluation were developed. The efficiency and accuracy of using hESC model for cytoxicity, embryotoxicity and genotoxicity evaluation were confirmed. The results indicated that hESCs might be good tools for toxicity testing and biosafety evaluation in vitro.

  15. Sublethal toxicant effects with dynamic energy budget theory: model formulation.

    PubMed

    Muller, Erik B; Nisbet, Roger M; Berkley, Heather A

    2010-01-01

    We develop and test a general modeling framework to describe the sublethal effects of pollutants by adding toxicity modules to an established dynamic energy budget (DEB) model. The DEB model describes the rates of energy acquisition and expenditure by individual organisms; the toxicity modules describe how toxicants affect these rates by changing the value of one or more DEB parameters, notably the parameters quantifying the rates of feeding and maintenance. We investigate four toxicity modules that assume: (1) effects on feeding only; (2) effects on maintenance only; (3) effects on feeding and maintenance with similar values for the toxicity parameters; and (4) effects on feeding and maintenance with different values for the toxicity parameters. We test the toxicity modules by fitting each to published data on feeding, respiration, growth and reproduction. Among the pollutants tested are metals (mercury and copper) and various organic compounds (chlorophenols, toluene, polycyclic aromatic hydrocarbons, tetradifon and pyridine); organisms include mussels, oysters, earthworms, water fleas and zebrafish. In most cases, the data sets could be adequately described with any of the toxicity modules, and no single module gave superior fits to all data sets. We therefore propose that for many applications, it is reasonable to use the most general and parameter sparse module, i.e. module 3 that assumes similar effects on feeding and maintenance, as a default. For one example (water fleas), we use parameter estimates to calculate the impact of food availability and toxicant levels on the long term population growth rate.

  16. Assessing Reproductive Toxicity of Two Environmental Toxicants with a Novel in vitro Human Spermatogenic Model

    PubMed Central

    Easley, Charles A.; Bradner, Joshua M.; Moser, Amber; Rickman, Chelsea A.; McEachin, Zachary T.; Merritt, Megan M.; Hansen, Jason M.; Caudle, W. Michael

    2015-01-01

    Environmental influences and insults by reproductive toxicant exposure can lead to impaired spermatogenesis or infertility. Understanding how toxicants disrupt spermatogenesis is critical for determining how environmental factors contribute to impaired fertility. While current animal models are available, understanding of the reproductive toxic effects on human fertility requires a more robust model system. We recently demonstrated that human pluripotent stem cells can differentiate into spermatogonial stem cells/spermatogonia, primary and secondary spermatocytes, and haploid spermatids; a model that mimics many aspects of human spermatogenesis. Here, using this model system, we examine the effects of 2-bromopropane (2-BP) and 1–2, Dibromo-3-chloropropane (DBCP) on in vitro human spermatogenesis. 2-BP and DBCP are non-endocrine disrupting toxicants that are known to impact male fertility. We show that acute treatment with either 2-BP or DBCP induces a reduction in germ cell viability through apoptosis. 2-BP and DBCP affect viability of different cell populations as 2-BP primarily reduces spermatocyte viability whereas DBCP exerts a much greater effect on spermatogonia. Acute treatment with 2-BP or DBCP also reduces the percentage of haploid spermatids. Both 2-BP and DBCP induce reactive oxygen species (ROS) formation leading to an oxidized cellular environment. Taken together, these results suggest that acute exposure with 2-BP or DBCP causes human germ cell death in vitro by inducing ROS formation. This system represents a unique platform for assessing human reproductive toxicity potential of various environmental toxicants in a rapid, efficient, and unbiased format. PMID:25863443

  17. Developing an Experimental Model of Vascular Toxicity in Embryonic Zebrafish

    EPA Science Inventory

    Developing an Experimental Model of Vascular Toxicity in Embryonic Zebrafish Tamara Tal, Integrated Systems Toxicology Division, U.S. EPA Background: There are tens of thousands of chemicals that have yet to be fully evaluated for their toxicity by validated in vivo testing ...

  18. National Air Toxics Information Clearinghouse: bibliography of selected reports and Federal Register notices related to air toxics. Volume 1. Citations. Interim report

    SciTech Connect

    Owen, C.A.; Hanson, M.L.; Wall, T.M.; Pelland, A.S.

    1987-07-01

    This report provides State and local agencies and other Clearinghouse users with citations to reports and Federal Register notices useful in developing and operating air-toxics control programs. The reports selected for the bibliography were published by the following agencies, EPA, NAS, NCI, NIEHS, NTP, NIOSH, and WHO. Reports published by various State and local agencies are also included. The report is published in two volumes. Volume 1, Part 1 includes introductory material describing the scope and organization and contains information necessary for the proper use of the document. Volume 1, Part 2 contains the report and Federal Register notice entries with bibliographic information and, in most cases, an abstract. Volume 2 consists of an index to the reports by document type; pollutant by class, name, or Chemical Abstracts Service (CAS) number; source category by Standard Industrial Classification (SIC) code; and sponsoring agency.

  19. The Double Counting Problem in Neighborhood Scale Air Quality Modeling

    NASA Astrophysics Data System (ADS)

    Du, S.; Hughes, V.; Woodhouse, L.; Servin, A.

    2004-12-01

    Air quality varies considerably within megacities. In certain neighborhoods concentrations of toxic air contaminants (TACs) can be appreciably higher than that in other neighborhoods of the same city. These pockets of high concentrations are associated with both transport of TACs from other areas and local emissions. In order to assess the health risks imposed by TACs at neighborhood scale and to develop strategies of abatement, neighborhood scale air quality modeling is needed. In 1999, the California Air Resources Board (ARB) established the Neighborhood Assessment Program (NAP) - a program designed to develop assessment tools for evaluating and understanding air quality in California communities. As part of the Neighborhood Assessment Program, ARB is conducting research on neighborhood-scale modeling methodologies. Two criteria are suggested to select a neighborhood scale air quality modeling system that can be used to assess concentrations of TACs: scientific soundness and balancing computational requirements. The latter criterion ensures that as many interested parties as possible can participate the process of air quality modeling so that they have a better understanding of air quality issues and make best use of air quality modeling results in their neighborhoods. Based on these two selection criteria a hybrid approach is recommended. This hybrid approach is a combination of using both a regional scale air quality model to assess the contributions from sources that are not located within the neighborhood of interest and a microscale model to assess the impact from the local sources that are within the neighborhood. However, one of the modeling system selection criteria, balancing computational requirements, dictates that all sources (both within and outside the neighborhood of interest) must be included in the regional scale modeling. A potential problem, referred to as double counting, arises because some local sources are included in both regional and

  20. Virtual Embryo: Systems Modeling in Developmental Toxicity

    EPA Science Inventory

    High-throughput and high-content screening (HTS-HCS) studies are providing a rich source of data that can be applied to in vitro profiling of chemical compounds for biological activity and potential toxicity. EPA’s ToxCast™ project, and the broader Tox21 consortium, in addition t...

  1. The CAESAR models for developmental toxicity

    EPA Science Inventory

    The new REACH legislation requires assessment of a high number of chemicals in the European market for several endpoints. Developmental Toxicity results amongst the most difficult endpoint to assess, due to the complexity, length and costs of experiments. Following the encouragem...

  2. In Vitro Models of Human Toxicity Pathways

    EPA Science Inventory

    For toxicity testing and assessment programs to address the large numbers of substances of potential concern, a paradigm shift in the assessment of chemical hazard and risk is needed that takes advantage of advances in molecular toxicology, computational sciences, and information...

  3. Evaluation of a possible association of urban air toxics and asthma

    SciTech Connect

    Leikauf, G.D.; Kline, S.; Albert, R.E.; Baxter, C.S.

    1995-09-01

    The prevalence of asthma, measured either as the frequency of hospital admission or number of deaths attributed to asthma, has increased over the last 15 to 20 years. Rapid increases in disease prevalence are more likely to be attributable to environmental than genetic factors. inferring from past associations between air pollution and asthma, it is feasible that changes in the ambient environment could contribute to this increase in morbidity and mortality. Scientific evaluation of the links between air pollution and the exacerbation of asthma is incomplete, however. Currently, criteria pollutants [SO{sub x}NO{sub x}, O{sub 3}, CO, Pb, particulate matter (PM{sub 10})] and other risk factors (exposure to environmental tobacco smoke, volatile organic compounds, etc.) are constantly being evaluated as to their possible contributions to this situation. Data from these studies suggest that increases in respiratory disease are associated with exposures to ambient concentrations of particulate and gaseous pollutants. Similarly, exposure to environmental tobacco smoke, also a mixture of particles and gases and that current measurements of air pollution are, in part, indirect in that the concentrations of criteria pollutants are acting as surrogates of our exposure to a complex mixture. Other irritant air pollutants, including certain urban air toxics, are associated with asthma in occupational settings and may interact with criteria pollutants in ambient air to exacerbate asthma. 179 refs., 2 figs., 18 tabs.

  4. Simulation model air-to-air plate heat exchanger

    SciTech Connect

    Wetter, Michael

    1999-01-01

    A simple simulation model of an air-to-air plate heat exchanger is presented. The model belongs to a collection of simulation models that allows the eflcient computer simulation of heating, ventilation, and air-conditioning (HVAC) systems. The main emphasis of the models is to shorten computation time and to use only input data that are known in the design process of an HVAC system. The target of the models is to describe the behavior of HVAC components in the part-load operation mode, which is becoming increasingly important in energy eficient HVAC systems. The models are intended to be used for yearly energy calculations or load calculations with time steps of about 10 minutes or larger. Short- time dynamic effects, which are of interest for different aspects of control theory, are neglected. The part-load behavior is expressed in terms of the nominal condition and the dimensionless variation of the heat transfer with change of mass flow and temperature. The effectiveness- NTU relations are used to parametrize the convective heat transfer at nominal conditions and to compute the part-load condition. If the heat transfer coefficients on the two exchanger sides are not equal (i. e. due to partial bypassing of air), their ratio can be easily calculated and set as a parameter. The model is static and uses explicit equations only. The explicit model formulation ensures short computation time and numerical stability, which allows using the model with sophisticated engineering methods like automatic system optimization. This paper fully outlines the algorithm description and its simplifications. It is not tailored for any particular simulation program to ensure easy implementation in any simulation program.

  5. Notification: Background Investigation Services New Assignment Notification: EPA’s Efforts to Incorporate Environmental Justice Into Clean Air Act Inspections for Air Toxics

    EPA Pesticide Factsheets

    The purpose of this memorandum is to notify you that the EPA OIG plans to begin the preliminary research phase of an evaluation of the U.S. EPA's efforts to incorporate environmental justice into Clean Air Act inspections for air toxics.

  6. QSAR trout toxicity models on aromatic pesticides.

    PubMed

    Slavov, Svetoslav; Gini, Giuseppina; Benfenati, Emilio

    2008-11-01

    The pesticides originally designed to kill target organisms are dangerous for many other wild species. Since they are applied directly to the environment, they can easily reach the water basins and the topsoil. A dataset of 125 aromatic pesticides with well-expressed aquatic toxicity towards trout was subjected to quantitative structure activity relationships (QSAR) analysis aimed to establish the relationship between their molecular structure and biological activity. A literature data for LC50 concentration killing 50% of fish was used. In addition to the standard 2D-QSAR analysis, a comparative molecular field analysis (CoMFA) analysis considering the electrostatic and steric properties of the molecules was also performed. The CoMFA analysis helped the recognition of the steric interactions as playing an important role for aquatic toxicity. In addition, the transport properties and the stability of the compounds studied were also identified as important for their biological activity.

  7. New approaches to toxicity: a seven-gas predictive model and toxicant suppressants.

    PubMed

    Levin, B C

    1997-11-01

    Two new research approaches in combustion toxicology are: 1. the prediction of smoke toxicity from mathematical equations, which are empirically derived from, experiments on the toxicological interactions of complex fire gas mixtures and 2. the use of toxicant suppressants in materials or products to prevent the formation of toxic combustion products. The predictive approach consists of burning materials using a bench-scale method that simulates realistic fire conditions, measuring the concentrations of the primary fire gases--CO, CO2, low O2, HCN, HCl, HBr, and NO2--and predicting the toxicity of the smoke using either the 6- or 7-gas N-Gas Model. These models are based on the results of toxicological studies of these primary gases as individual gases and as complex mixtures. The predicted toxic potency is checked with a small number of animal (Fischer 344 male rats) tests to assure that an unanticipated toxic gas is not generated or an unexpected synergistic or antagonistic effect has not occurred. The results indicate if the smoke from a material or product is extremely toxic (based on mass consumed at the predicted toxic level) or unusually toxic (based on the gases deemed responsible). The predictions based on bench-scale laboratory tests have been validated with full-scale room burns of a limited number of materials of widely differing characteristics chosen to challenge the system. The advantages of this new approach are 1. the number of test animals is minimized by predicting the toxic potency from the chemical analysis of the smoke, 2. smoke may be produced under conditions that simulate the fire scenario of concern, 3. fewer tests are needed, thereby reducing the overall cost of the testing and 4, information is obtained on both the toxic potency of the smoke and the responsible gases. The N-Gas Models have been developed into the N-Gas Method (described in this paper) and these results have been used in computations of fire hazard. The 6-Gas Model is now

  8. Portable air pollution control equipment for the control of toxic particulate emissions

    SciTech Connect

    Chaurushia, A.; Odabashian, S.; Busch, E.

    1997-12-31

    Chromium VI (Cr VI) has been identified by the environmental regulatory agencies as a potent carcinogen among eleven heavy metals. A threshold level of 0.0001 lb/year for Cr VI emissions has been established by the California Air Resources Board for reporting under Assembly Bill 2588. A need for an innovative control technology to reduce fugitive emissions of Cr VI was identified during the Air Toxic Emissions Reduction Program at Northrop Grumman Military Aircraft Systems Division (NGMASD). NGMASD operates an aircraft assembly facility in El Segundo, CA. Nearly all of the aircraft components are coated with a protective coating (primer) prior to assembly. The primer has Cr VI as a component for its excellent corrosion resistance property. The complex assembly process requires fasteners which also need primer coating. Therefore, NGMASD utilizes High Volume Low Pressure (HVLP) guns for the touch-up spray coating operations. During the touch-up spray coating operations, Cr VI particles are atomized and transferred to the aircraft surface. The South Coast Air Quality Management District (SCAQMD) has determined that the HVLP gun transfers 65% of the paint particles onto the substrate and the remaining 35% are emitted as an overspray if air pollution controls are not applied. NGMASD has developed the Portable Air Pollution Control Equipment (PAPCE) to capture and control the overspray in order to reduce fugitive Cr VI emissions from the touch-up spray coating operations. A source test was performed per SCAQMD guidelines and the final report has been approved by the SCAQMD.

  9. NASA/Air Force Cost Model: NAFCOM

    NASA Technical Reports Server (NTRS)

    Winn, Sharon D.; Hamcher, John W. (Technical Monitor)

    2002-01-01

    The NASA/Air Force Cost Model (NAFCOM) is a parametric estimating tool for space hardware. It is based on historical NASA and Air Force space projects and is primarily used in the very early phases of a development project. NAFCOM can be used at the subsystem or component levels.

  10. Toxicity screening of materials from buildings with fungal indoor air quality problems (Stachybotrys chartarum).

    PubMed

    E, J; M, G; S, Y C; E-L, H; M, N; B, J; R, D

    1998-06-01

    Samples of building materials visibly contaminated with moisture-related fungi (drywall, fiberglass, wallpaper, wood) were tested with indirect (FFL) and direct (MTT) cytotoxicity screening tests that are particularly sensitive toStachybotrys chartarum toxins. In addition, microscopic, chemical, immunochemical (Roridin A enzyme immunoassay) and mycological culture analyses were performed. In all cases in which building occupants had reported verifiable skin, mucous membrane, respiratory, central nervous system or neuropsychological abnormalities, cytotoxicity was identified. Results of a cytotoxicity screening test of field samples, such as the direct MTT test method, will give investigators of health problems related to indoor air quality problems important toxicity information.

  11. Toxicity of silver nanoparticles in zebrafish models.

    PubMed

    Asharani, P V; Lian Wu, Yi; Gong, Zhiyuan; Valiyaveettil, Suresh

    2008-06-25

    This study was initiated to enhance our insight on the health and environmental impact of silver nanoparticles (Ag-np). Using starch and bovine serum albumin (BSA) as capping agents, silver nanoparticles were synthesized to study their deleterious effects and distribution pattern in zebrafish embryos (Danio rerio). Toxicological endpoints like mortality, hatching, pericardial edema and heart rate were recorded. A concentration-dependent increase in mortality and hatching delay was observed in Ag-np treated embryos. Additionally, nanoparticle treatments resulted in concentration-dependent toxicity, typified by phenotypes that had abnormal body axes, twisted notochord, slow blood flow, pericardial edema and cardiac arrhythmia. Ag(+) ions and stabilizing agents showed no significant defects in developing embryos. Transmission electron microscopy (TEM) of the embryos demonstrated that nanoparticles were distributed in the brain, heart, yolk and blood of embryos as evident from the electron-dispersive x-ray analysis (EDS). Furthermore, the acridine orange staining showed an increased apoptosis in Ag-np treated embryos. These results suggest that silver nanoparticles induce a dose-dependent toxicity in embryos, which hinders normal development.

  12. Air Tightness of US Homes: Model Development

    SciTech Connect

    Sherman, Max H.

    2006-05-01

    Air tightness is an important property of building envelopes. It is a key factor in determining infiltration and related wall-performance properties such as indoor air quality, maintainability and moisture balance. Air leakage in U.S. houses consumes roughly 1/3 of the HVAC energy but provides most of the ventilation used to control IAQ. The Lawrence Berkeley National Laboratory has been gathering residential air leakage data from many sources and now has a database of more than 100,000 raw measurements. This paper uses that database to develop a model for estimating air leakage as a function of climate, building age, floor area, building height, floor type, energy-efficiency and low-income designations. The model developed can be used to estimate the leakage distribution of populations of houses.

  13. Spatial Allocator for air quality modeling

    EPA Pesticide Factsheets

    The Spatial Allocator is a set of tools that helps users manipulate and generate data files related to emissions and air quality modeling without requiring the use of a commercial Geographic Information System.

  14. EVALUATING AND USING AIR QUALITY MODELS

    EPA Science Inventory

    Grid-based models are being used to assess the magnitude of the pollution problem and to design emission control strategies to achieve compliance with the relevant air quality standards in the United States.

  15. Polychlorinated naphthalenes in the air over the equatorial Indian Ocean: Occurrence, potential sources, and toxicity.

    PubMed

    Huang, Yumei; Li, Jun; Xu, Yue; Xu, Weihai; Zhong, Guangcai; Liu, Xiang; Zhang, Gan

    2016-06-15

    Monitoring of marine polychlorinated naphthalenes (PCNs) is crucial, as they are considered persistent organic pollutants (POPs) by the Stockholm Convention. Data on PCNs in marine environment are scarce. In this study, 19 air samples were collected during a cruise in the equatorial Indian Ocean on board the Chinese research vessel Shiyan I from 4/2011 to 5/2011. PCN concentration of these air samples ranged from 0.033 to 2.56pgm(-3), with an average of 0.518pgm(-3), equal to or lower than the values reported for other oceans, seas, and lakes worldwide. Tri- and tetra-CNs were the main homologues in most samples. Reemission of Halowax mixtures and incineration processes were the major sources of atmospheric PCNs in the study area. The PCN-corresponding toxic equivalency values ranged from 0 to 0.190fgm(-3) (average: 0.038fgm(-3)), falling in the low end of global range.

  16. Ranking of aquatic toxicity of esters modelled by QSAR.

    PubMed

    Papa, Ester; Battaini, Francesca; Gramatica, Paola

    2005-02-01

    Alternative methods like predictions based on Quantitative Structure-Activity Relationships (QSARs) are now accepted to fill data gaps and define priority lists for more expensive and time consuming assessments. A heterogeneous data set of 74 esters was studied for their aquatic toxicity, and available experimental toxicity data on algae, Daphnia and fish were used to develop statistically validated QSAR models, obtained using multiple linear regression (MLR) by the OLS (Ordinary Least Squares) method and GA-VSS (Variable Subset Selection by Genetic Algorithms) to predict missing values. An ESter Aquatic Toxicity INdex (ESATIN) was then obtained by combining, by PCA, experimental and predicted toxicity data, from which model outliers and esters highly influential due to their structure had been eliminated. Finally this integrated aquatic toxicity index, defined by the PC1 score, was modelled using only a few theoretical molecular descriptors. This last QSAR model, statistically validated for its predictive power, could be proposed as a preliminary evaluative method for screening/prioritising esters according to their integrated aquatic toxicity, just starting from their molecular structure.

  17. Models of inflammation: carrageenan air pouch.

    PubMed

    Duarte, Djane B; Vasko, Michael R; Fehrenbacher, Jill C

    2012-03-01

    The subcutaneous air pouch is an in vivo model that can be used to study acute and chronic inflammation, the resolution of the inflammatory response, and the oxidative stress response. Injection of irritants into an air pouch in rats or mice induces an inflammatory response that can be quantified by the volume of exudate produced, the infiltration of cells, and the release of inflammatory mediators. The model presented in this unit has been extensively used to identify potential anti-inflammatory drugs.

  18. Projections of air toxic emissions from coal-fired utility combustion: Input for hazardous air pollutant regulators

    SciTech Connect

    Szpunar, C.B.

    1993-08-01

    The US Environmental Protection Agency (EPA) is required by the 1990 CAAA to promulgate rules for all ``major`` sources of any of these HAPs. According to the HAPs section of the new Title III, any stationary source emitting 10 tons per year (TPY) of one HAP or 25 TPY of a combination of HAPs will be considered and designated a major source. In contrast to the original National Emission Standards for Hazardous Air Pollutants (NESHAP), which were designed to protect public health to ``an ample margin of safety,`` the new Title III, in its first phase, will regulate by industrial category those sources emitting HAPs in excess of the 10/25-TPY threshold levels, regardless of health risks. The trace elements normally associated with coal mineral matter and the various compounds formed during coal combustion have the potential to produce hazardous air toxic emissions from coal-fired electric utilities. Under Title III, the EPA is required to perform certain studies, prior to any regulation of electric utilities; these studies are currently underway. Also, the US Department of Energy (DOE) maintains a vested interest in addressing those energy policy questions affecting electric utility generation, coal mining, and steel producing critical to this country`s economic well-being, where balancing the costs to the producers and users of energy with the benefits of environmental protection to the workers and the general populace remains of significant concern.

  19. Assessment and prediction of air quality using fuzzy logic and autoregressive models

    NASA Astrophysics Data System (ADS)

    Carbajal-Hernández, José Juan; Sánchez-Fernández, Luis P.; Carrasco-Ochoa, Jesús A.; Martínez-Trinidad, José Fco.

    2012-12-01

    In recent years, artificial intelligence methods have been used for the treatment of environmental problems. This work, presents two models for assessment and prediction of air quality. First, we develop a new computational model for air quality assessment in order to evaluate toxic compounds that can harm sensitive people in urban areas, affecting their normal activities. In this model we propose to use a Sigma operator to statistically asses air quality parameters using their historical data information and determining their negative impact in air quality based on toxicity limits, frequency average and deviations of toxicological tests. We also introduce a fuzzy inference system to perform parameter classification using a reasoning process and integrating them in an air quality index describing the pollution levels in five stages: excellent, good, regular, bad and danger, respectively. The second model proposed in this work predicts air quality concentrations using an autoregressive model, providing a predicted air quality index based on the fuzzy inference system previously developed. Using data from Mexico City Atmospheric Monitoring System, we perform a comparison among air quality indices developed for environmental agencies and similar models. Our results show that our models are an appropriate tool for assessing site pollution and for providing guidance to improve contingency actions in urban areas.

  20. Sampling of air streams and incorporation of samples in the Microtox{trademark} toxicity testing system

    SciTech Connect

    Kleinheinz, G.T.; St. John, W.P.

    1997-10-01

    A study was conducted to develop a rapid and reliable method for the collection and incorporation of biofiltration air samples containing volatile organic compounds (VOCs) into the Microtox toxicity testing system. To date, no method exists for this type of assay. A constant stream of VOCs was generated by air stripping compounds from a complex mixture of petroleum hydrocarbons (PHCs). Samples were collected on coconut charcoal ORBO tubes and the VOCs extracted with methylene chloride. The compounds extracted were then solvent exchanged into dimethyl sulfoxide (DMSO) under gaseous nitrogen. The resulting DMSO extract was directly incorporated into the Microtox toxicity testing system. In order to determine the efficiency of the solvent exchange, the VOCs in the DMSO extract were then extracted into hexane and subsequently analyzed using gas chromatography (GC) with a flame ionization detector (FID). It was determined that all but the most volatile VOCs could be effectively transferred from the ORBO tubes to DMSO for Microtox testing. Potential trace amounts of residual methylene chloride in the DMSO extracts showed no adverse effects in the Microtox system when compared to control samples.

  1. Uncertainty for data with non-detects: Air toxic emissions from combustion

    SciTech Connect

    Zhao, Y.C.; Frey, H.C.

    2006-12-15

    Air toxic emission factor datasets often contain one or more points below a single or multiple detection limits and such datasets are referred to as 'censored.' Conventional methods used to deal with censored datasets include removing non-detects, replacing the censored points with zero, half of the detection limit, or the detection limit. However, the estimated means of the censored dataset by conventional methods are usually biased. Maximum likelihood estimation (MLE) and bootstrap simulation have been demonstrated as a statistically robust method to quantify variability and uncertainty of censored datasets and can provide asymptotically unbiased mean estimates. The MLE/bootstrap method is applied to 16 cases of censored air toxic emission factors, including benzene, formaldehyde, benzo(a)pyrene, mercury, arsenic, cadmium, total chromium, chromium VI and lead from coal, fuel oil, and/or wood waste external combustion sources. The proportion of censored values in the emission factor data ranges from 4 to 80%. Key factors that influence the estimated uncertainty in the mean of censored data are sample size and inter-unit variability. The largest range of uncertainty in the mean was obtained for the external coal combustion benzene emission factor, with 95 confidence interval of the mean equal to minus 93 to plus 411%.

  2. Studies with the USF/NASA toxicity screening test method - Effect of air flow and effect of fabric dye

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Lopez, M. T.

    1976-01-01

    One sample each of commercial polyurethane and polychloroprene flexible foams were evaluated using the USF/NASA toxicity screening test method. Air flow rates of 0, 0.16, 16, and 48 ml/sec were used to determine the effect of air flow on relative toxicity. Time to first sign of incapacitation and time to death were substantially reduced with both polyurethane and polychloroprene flexible foams by the introduction of 16 to 48 ml/sec air flow. The relative toxicity rankings of these materials were not altered by changes in air flow. Under these test conditions, the polyurethane foam consistently appeared more toxic than the polychloroprene foam. Samples of six different colors from the same fabric were evaluated separately, using the USF/NASA toxicity screening test method, to determine the effect of fabric dye, if any. The material was an upholstery fabric, consisting of 46 percent cotton, 33 percent wool, and 21 percent nylon. There appeared to be no significant effect of fabric dye on relative toxicity, for this material under these test conditions.

  3. A Bayesian network model for predicting aquatic toxicity mode ...

    EPA Pesticide Factsheets

    The mode of toxic action (MoA) has been recognized as a key determinant of chemical toxicity, but development of predictive MoA classification models in aquatic toxicology has been limited. We developed a Bayesian network model to classify aquatic toxicity MoA using a recently published dataset containing over one thousand chemicals with MoA assignments for aquatic animal toxicity. Two dimensional theoretical chemical descriptors were generated for each chemical using the Toxicity Estimation Software Tool. The model was developed through augmented Markov blanket discovery from the dataset of 1098 chemicals with the MoA broad classifications as a target node. From cross validation, the overall precision for the model was 80.2%. The best precision was for the AChEI MoA (93.5%) where 257 chemicals out of 275 were correctly classified. Model precision was poorest for the reactivity MoA (48.5%) where 48 out of 99 reactive chemicals were correctly classified. Narcosis represented the largest class within the MoA dataset and had a precision and reliability of 80.0%, reflecting the global precision across all of the MoAs. False negatives for narcosis most often fell into electron transport inhibition, neurotoxicity or reactivity MoAs. False negatives for all other MoAs were most often narcosis. A probabilistic sensitivity analysis was undertaken for each MoA to examine the sensitivity to individual and multiple descriptor findings. The results show that the Markov blank

  4. Modeling of global surface air temperature

    NASA Astrophysics Data System (ADS)

    Gusakova, M. A.; Karlin, L. N.

    2012-04-01

    A model to assess a number of factors, such as total solar irradiance, albedo, greenhouse gases and water vapor, affecting climate change has been developed on the basis of Earth's radiation balance principle. To develop the model solar energy transformation in the atmosphere was investigated. It's a common knowledge, that part of the incoming radiation is reflected into space from the atmosphere, land and water surfaces, and another part is absorbed by the Earth's surface. Some part of outdoing terrestrial radiation is retained in the atmosphere by greenhouse gases (carbon dioxide, methane, nitrous oxide) and water vapor. Making use of the regression analysis a correlation between concentration of greenhouse gases, water vapor and global surface air temperature was obtained which, it is turn, made it possible to develop the proposed model. The model showed that even smallest fluctuations of total solar irradiance intensify both positive and negative feedback which give rise to considerable changes in global surface air temperature. The model was used both to reconstruct the global surface air temperature for the 1981-2005 period and to predict global surface air temperature until 2030. The reconstructions of global surface air temperature for 1981-2005 showed the models validity. The model makes it possible to assess contribution of the factors listed above in climate change.

  5. Race, deprivation, and immigrant isolation: The spatial demography of air-toxic clusters in the continental United States.

    PubMed

    Liévanos, Raoul S

    2015-11-01

    This article contributes to environmental inequality outcomes research on the spatial and demographic factors associated with cumulative air-toxic health risks at multiple geographic scales across the United States. It employs a rigorous spatial cluster analysis of census tract-level 2005 estimated lifetime cancer risk (LCR) of ambient air-toxic emissions from stationary (e.g., facility) and mobile (e.g., vehicular) sources to locate spatial clusters of air-toxic LCR risk in the continental United States. It then tests intersectional environmental inequality hypotheses on the predictors of tract presence in air-toxic LCR clusters with tract-level principal component factor measures of economic deprivation by race and immigrant status. Logistic regression analyses show that net of controls, isolated Latino immigrant-economic deprivation is the strongest positive demographic predictor of tract presence in air-toxic LCR clusters, followed by black-economic deprivation and isolated Asian/Pacific Islander immigrant-economic deprivation. Findings suggest scholarly and practical implications for future research, advocacy, and policy.

  6. Assaying environmental nickel toxicity using model nematodes

    USGS Publications Warehouse

    Rudel, David; Douglas, Chandler; Huffnagle, Ian; Besser, John M.; Ingersoll, Christopher G.

    2013-01-01

    Although nickel exposure results in allergic reactions, respiratory conditions, and cancer in humans and rodents, the ramifications of excess nickel in the environment for animal and human health remain largely undescribed. Nickel and other cationic metals travel through waterways and bind to soils and sediments. To evaluate the potential toxic effects of nickel at environmental contaminant levels (8.9-7,600 µg Ni/g dry weight of sediment and 50-800 µg NiCl2/L of water), we conducted assays using two cosmopolitan nematodes, Caenorhabditis elegans and Pristionchus pacificus. We assayed the effects of both sediment-bound and aqueous nickel upon animal growth, developmental survival, lifespan, and fecundity. Uncontaminated sediments were collected from sites in the Midwestern United States and spiked with a range of nickel concentrations. We found that nickel-spiked sediment substantially impairs both survival from larval to adult stages and adult longevity in a concentration-dependent manner. Further, while aqueous nickel showed no adverse effects on either survivorship or longevity, we observed a significant decrease in fecundity, indicating that aqueous nickel could have a negative impact on nematode physiology. Intriguingly, C. elegansand P. pacificus exhibit similar, but not identical, responses to nickel exposure. Moreover, P. pacificus could be tested successfully in sediments inhospitable to C. elegans. Our results add to a growing body of literature documenting the impact of nickel on animal physiology, and suggest that environmental toxicological studies could gain an advantage by widening their repertoire of nematode species.

  7. Assaying environmental nickel toxicity using model nematodes.

    PubMed

    Rudel, David; Douglas, Chandler D; Huffnagle, Ian M; Besser, John M; Ingersoll, Christopher G

    2013-01-01

    Although nickel exposure results in allergic reactions, respiratory conditions, and cancer in humans and rodents, the ramifications of excess nickel in the environment for animal and human health remain largely undescribed. Nickel and other cationic metals travel through waterways and bind to soils and sediments. To evaluate the potential toxic effects of nickel at environmental contaminant levels (8.9-7,600 µg Ni/g dry weight of sediment and 50-800 µg NiCl2/L of water), we conducted assays using two cosmopolitan nematodes, Caenorhabditis elegans and Pristionchus pacificus. We assayed the effects of both sediment-bound and aqueous nickel upon animal growth, developmental survival, lifespan, and fecundity. Uncontaminated sediments were collected from sites in the Midwestern United States and spiked with a range of nickel concentrations. We found that nickel-spiked sediment substantially impairs both survival from larval to adult stages and adult longevity in a concentration-dependent manner. Further, while aqueous nickel showed no adverse effects on either survivorship or longevity, we observed a significant decrease in fecundity, indicating that aqueous nickel could have a negative impact on nematode physiology. Intriguingly, C. elegans and P. pacificus exhibit similar, but not identical, responses to nickel exposure. Moreover, P. pacificus could be tested successfully in sediments inhospitable to C. elegans. Our results add to a growing body of literature documenting the impact of nickel on animal physiology, and suggest that environmental toxicological studies could gain an advantage by widening their repertoire of nematode species.

  8. Assaying Environmental Nickel Toxicity Using Model Nematodes

    PubMed Central

    Rudel, David; Douglas, Chandler D.; Huffnagle, Ian M.; Besser, John M.; Ingersoll, Christopher G.

    2013-01-01

    Although nickel exposure results in allergic reactions, respiratory conditions, and cancer in humans and rodents, the ramifications of excess nickel in the environment for animal and human health remain largely undescribed. Nickel and other cationic metals travel through waterways and bind to soils and sediments. To evaluate the potential toxic effects of nickel at environmental contaminant levels (8.9-7,600 µg Ni/g dry weight of sediment and 50-800 µg NiCl2/L of water), we conducted assays using two cosmopolitan nematodes, Caenorhabditis elegans and Pristionchus pacificus. We assayed the effects of both sediment-bound and aqueous nickel upon animal growth, developmental survival, lifespan, and fecundity. Uncontaminated sediments were collected from sites in the Midwestern United States and spiked with a range of nickel concentrations. We found that nickel-spiked sediment substantially impairs both survival from larval to adult stages and adult longevity in a concentration-dependent manner. Further, while aqueous nickel showed no adverse effects on either survivorship or longevity, we observed a significant decrease in fecundity, indicating that aqueous nickel could have a negative impact on nematode physiology. Intriguingly, C. elegans and P. pacificus exhibit similar, but not identical, responses to nickel exposure. Moreover, P. pacificus could be tested successfully in sediments inhospitable to C. elegans. Our results add to a growing body of literature documenting the impact of nickel on animal physiology, and suggest that environmental toxicological studies could gain an advantage by widening their repertoire of nematode species. PMID:24116204

  9. Toxicity of Nanoparticles and an Overview of Current Experimental Models

    PubMed Central

    Bahadar, Haji; Maqbool, Faheem; Niaz, Kamal; Abdollahi, Mohammad

    2016-01-01

    Nanotechnology is a rapidly growing field having potential applications in many areas. Nanoparticles (NPs) have been studied for cell toxicity, immunotoxicity, and genotoxicity. Tetrazolium-based assays such as MTT, MTS, and WST-1 are used to determine cell viability. Cell inflammatory response induced by NPs is checked by measuring inflammatory biomarkers, such as IL-8, IL-6, and tumor necrosis factor, using ELISA. Lactate dehydrogenase (LDH) assay is used for cell membrane integrity. Different types of cell cultures, including cancer cell lines have been employed as in vitro toxicity models. It has been generally agreed that NPs interfere with either assay materials or with detection systems. So far, toxicity data generated by employing such models are conflicting and inconsistent. Therefore, on the basis of available experimental models, it may be difficult to judge and list some of the more valuable NPs as more toxic to biological systems and vice versa. Considering the potential applications of NPs in many fields and the growing apprehensions of FDA about the toxic potential of nanoproducts, it is the need of the hour to look for new internationally agreed free of bias toxicological models by focusing more on in vivo studies. PMID:26286636

  10. An exploratory study of ambient air toxics exposure in pregnancy and the risk of neuroblastoma in offspring

    PubMed Central

    Heck, Julia E; Park, Andrew S.; Qiu, Jiaheng; Cockburn, Myles; Ritz, Beate

    2013-01-01

    Little is known about the etiology of neuroblastoma, the most common cancer in infancy. In this study, we examined maternal exposure to ambient air toxics in pregnancy in relation to neuroblastoma in the child. We ascertained all cases of neuroblastoma listed in the California Cancer Registry 1990-2007 that could be linked to a California birth certificate, and controls were selected at random from California birth records. Average air toxics exposures during pregnancy were determined based upon measures from community-based air pollution monitors. The study included 75 cases and 14,602 controls who lived with 5 kilometers of an air pollution monitor, and we additionally examined results for those living within a smaller radius around the monitor (2.5 km). Logistic regression was used to determine the risk of neuroblastoma with one interquartile range increase in air toxic exposure. Neuroblastoma risk was increased with higher maternal exposure to carbon tetrachloride (OR=2.65, 95%CI 1.07, 6.53) and polycyclic aromatic hydrocarbons (OR=1.39, 95%CI 1.05, 1.84), particularly indeno(1,2,3-cd)pyrene and dibenz(a,h)anthracene. Hexavalent chromium was associated with neuroblastoma at the 5 km distance (OR=1.32, 95%CI 1.00, 1.74) but not at the 2.5 km distance. This is one of the first studies to report associations between neuroblastoma and these air toxics. PMID:24139061

  11. Modeling monthly mean air temperature for Brazil

    NASA Astrophysics Data System (ADS)

    Alvares, Clayton Alcarde; Stape, José Luiz; Sentelhas, Paulo Cesar; de Moraes Gonçalves, José Leonardo

    2013-08-01

    Air temperature is one of the main weather variables influencing agriculture around the world. Its availability, however, is a concern, mainly in Brazil where the weather stations are more concentrated on the coastal regions of the country. Therefore, the present study had as an objective to develop models for estimating monthly and annual mean air temperature for the Brazilian territory using multiple regression and geographic information system techniques. Temperature data from 2,400 stations distributed across the Brazilian territory were used, 1,800 to develop the equations and 600 for validating them, as well as their geographical coordinates and altitude as independent variables for the models. A total of 39 models were developed, relating the dependent variables maximum, mean, and minimum air temperatures (monthly and annual) to the independent variables latitude, longitude, altitude, and their combinations. All regression models were statistically significant ( α ≤ 0.01). The monthly and annual temperature models presented determination coefficients between 0.54 and 0.96. We obtained an overall spatial correlation higher than 0.9 between the models proposed and the 16 major models already published for some Brazilian regions, considering a total of 3.67 × 108 pixels evaluated. Our national temperature models are recommended to predict air temperature in all Brazilian territories.

  12. EPAs Virtual Embryo: Modeling Developmental Toxicity

    EPA Science Inventory

    Embryogenesis is regulated by concurrent activities of signaling pathways organized into networks that control spatial patterning, molecular clocks, morphogenetic rearrangements and cell differentiation. Quantitative mathematical and computational models are needed to better unde...

  13. Endangered species toxicity extrapolation using ICE models

    EPA Science Inventory

    The National Research Council’s (NRC) report on assessing pesticide risks to threatened and endangered species (T&E) included the recommendation of using interspecies correlation models (ICE) as an alternative to general safety factors for extrapolating across species. ...

  14. Air target models for fuzing simulations

    NASA Astrophysics Data System (ADS)

    Dammann, J. F., Jr.

    1982-09-01

    Radar backscatter models for air targets suitable for computer simulation of radar fuze-air target encounters are described. These models determine the characteristics of the energy reflected to the fuze when the target is illuminated by a fuze radar. When the target models are coupled with fuze models, the time when the fuze detects the presence of the target can be determined for any arbitrary terminal encounter geometry. Fuze detection times for representative trajectories can be compared with fuze specifications to measure fuze performance or can be used as a part of a simulation of an entire system to determine system performance. Following one basic methodology, target models have been written for the Fishbed, Foxbat, and Flogger fighter aircraft; the Hind-D helicopter; and the Backfire, Blinder, and B-1 bombers. All of the models are specular point models where the major return is assumed to come from a small number of glitter points or specular points on the target.

  15. Real time measurement of transient event emissions of air toxics by tomographic remote sensing in tandem with mobile monitoring

    NASA Astrophysics Data System (ADS)

    Olaguer, Eduardo P.; Stutz, Jochen; Erickson, Matthew H.; Hurlock, Stephen C.; Cheung, Ross; Tsai, Catalina; Colosimo, Santo F.; Festa, James; Wijesinghe, Asanga; Neish, Bradley S.

    2017-02-01

    During the Benzene and other Toxics Exposure (BEE-TEX) study, a remote sensing network based on long path Differential Optical Absorption Spectroscopy (DOAS) was set up in the Manchester neighborhood beside the Ship Channel of Houston, Texas in order to perform Computer Aided Tomography (CAT) scans of hazardous air pollutants. On 18-19 February 2015, the CAT scan network detected large nocturnal plumes of toluene and xylenes most likely associated with railcar loading and unloading operations at Ship Channel petrochemical facilities. The presence of such plumes during railcar operations was confirmed by a mobile laboratory equipped with a Proton Transfer Reaction-Mass Spectrometer (PTR-MS), which measured transient peaks of toluene and C2-benzenes of 50 ppb and 57 ppb respectively around 4 a.m. LST on 19 February 2015. Plume reconstruction and source attribution were performed using the 4D variational data assimilation technique and a 3D micro-scale forward and adjoint air quality model based on both tomographic and PTR-MS data. Inverse model estimates of fugitive emissions associated with railcar transfer emissions ranged from 2.0 to 8.2 kg/hr for toluene and from 2.2 to 3.5 kg/hr for xylenes in the early morning of 19 February 2015.

  16. Modelling interactions of toxicants and density dependence in wildlife populations

    USGS Publications Warehouse

    Schipper, Aafke M.; Hendriks, Harrie W.M.; Kauffman, Matthew J.; Hendriks, A. Jan; Huijbregts, Mark A.J.

    2013-01-01

    1. A major challenge in the conservation of threatened and endangered species is to predict population decline and design appropriate recovery measures. However, anthropogenic impacts on wildlife populations are notoriously difficult to predict due to potentially nonlinear responses and interactions with natural ecological processes like density dependence. 2. Here, we incorporated both density dependence and anthropogenic stressors in a stage-based matrix population model and parameterized it for a density-dependent population of peregrine falcons Falco peregrinus exposed to two anthropogenic toxicants [dichlorodiphenyldichloroethylene (DDE) and polybrominated diphenyl ethers (PBDEs)]. Log-logistic exposure–response relationships were used to translate toxicant concentrations in peregrine falcon eggs to effects on fecundity. Density dependence was modelled as the probability of a nonbreeding bird acquiring a breeding territory as a function of the current number of breeders. 3. The equilibrium size of the population, as represented by the number of breeders, responded nonlinearly to increasing toxicant concentrations, showing a gradual decrease followed by a relatively steep decline. Initially, toxicant-induced reductions in population size were mitigated by an alleviation of the density limitation, that is, an increasing probability of territory acquisition. Once population density was no longer limiting, the toxicant impacts were no longer buffered by an increasing proportion of nonbreeders shifting to the breeding stage, resulting in a strong decrease in the equilibrium number of breeders. 4. Median critical exposure concentrations, that is, median toxicant concentrations in eggs corresponding with an equilibrium population size of zero, were 33 and 46 μg g−1 fresh weight for DDE and PBDEs, respectively. 5. Synthesis and applications. Our modelling results showed that particular life stages of a density-limited population may be relatively insensitive to

  17. High-end exposure relationships of volatile air toxics and carbon monoxide to community-scale air monitoring stations in Atlanta, Chicago, and Houston.

    PubMed

    Fujita, Eric M; Zielinska, Barbara; Campbell, David E; Sagebiel, John C; Ollison, Will

    Evaporative and exhaust mobile source air toxic (MSAT) emissions of total volatile organic compounds, carbon monoxide, BTEX (benzene, toluene, ethylbenzene, and xylenes), formaldehyde, acetaldehyde, butadiene, methyl tertiary butyl ether, and ethanol were measured in vehicle-related high-end microenvironments (ME) under worst-case conditions plausibly simulating the >99th percentile of inhalation exposure concentrations in Atlanta (baseline gasoline), Chicago (ethanol-oxygenated gasoline), and Houston (methyl tertiary butyl either-oxygenated gasoline) during winter and summer seasons. High-end MSAT values as ratios of the corresponding measurements at nearby air monitoring stations exceeded the microenvironmental proximity factors used in regulatory exposure models, especially for refueling operations and MEs under reduced ventilation. MSAT concentrations were apportioned between exhaust and evaporative vehicle emissions in Houston where methyl tertiary butyl ether could be used as a vehicle emission tracer. With the exception of vehicle refueling operations, the results indicate that evaporative emissions are a minor component of high-end MSAT exposure concentrations.

  18. Combinatorial QSAR modeling of chemical toxicants tested against Tetrahymena pyriformis.

    PubMed

    Zhu, Hao; Tropsha, Alexander; Fourches, Denis; Varnek, Alexandre; Papa, Ester; Gramatica, Paola; Oberg, Tomas; Dao, Phuong; Cherkasov, Artem; Tetko, Igor V

    2008-04-01

    Selecting most rigorous quantitative structure-activity relationship (QSAR) approaches is of great importance in the development of robust and predictive models of chemical toxicity. To address this issue in a systematic way, we have formed an international virtual collaboratory consisting of six independent groups with shared interests in computational chemical toxicology. We have compiled an aqueous toxicity data set containing 983 unique compounds tested in the same laboratory over a decade against Tetrahymena pyriformis. A modeling set including 644 compounds was selected randomly from the original set and distributed to all groups that used their own QSAR tools for model development. The remaining 339 compounds in the original set (external set I) as well as 110 additional compounds (external set II) published recently by the same laboratory (after this computational study was already in progress) were used as two independent validation sets to assess the external predictive power of individual models. In total, our virtual collaboratory has developed 15 different types of QSAR models of aquatic toxicity for the training set. The internal prediction accuracy for the modeling set ranged from 0.76 to 0.93 as measured by the leave-one-out cross-validation correlation coefficient ( Q abs2). The prediction accuracy for the external validation sets I and II ranged from 0.71 to 0.85 (linear regression coefficient R absI2) and from 0.38 to 0.83 (linear regression coefficient R absII2), respectively. The use of an applicability domain threshold implemented in most models generally improved the external prediction accuracy but at the same time led to a decrease in chemical space coverage. Finally, several consensus models were developed by averaging the predicted aquatic toxicity for every compound using all 15 models, with or without taking into account their respective applicability domains. We find that consensus models afford higher prediction accuracy for the

  19. Ecotoxicological studies of environmental samples from Buenos Aires area using a standardized amphibian embryo toxicity test (AMPHITOX).

    PubMed

    Herkovits, Jorge; Perez-Coll, Cristina; Herkovits, Francisco D

    2002-01-01

    The toxicity of 34 environmental samples from potentially polluted and reference stations were evaluated by means of the AMPHITOX test from acute to chronic exposure according to the toxicity found in each sample. The samples were obtained from surface and ground water, leaches, industrial effluents and soils. The data, expressed in acute, short-term chronic and chronic Toxicity Units (TUa, TUstc and TUc) resulted in a maximal value of 1000 TUc, found in a leach, while the lower toxicity value was 1.4 TUa corresponding to two surface water samples. In five samples (four providing from reference places) no toxicity was detected. The results point out the possibility of evaluating the toxicity of a wide diversity of samples by means of AMPHITOX as a customized toxicity test. The fact that almost all samples with suspected toxicity in rivers and streams from the Metropolitan area of Buenos Aires city resulted toxic, indicates the need of enhanced stewardship of chemical substances for environmental and human health protection purposes.

  20. TOF-SIMS measurements for toxic air pollutants adsorbed on the surface of airborne particles

    NASA Astrophysics Data System (ADS)

    Tomiyasu, Bunbunoshin; Hoshi, Takahiro; Owari, Masanori; Nihei, Yoshimasa

    2003-01-01

    Three kinds of particulate matter were collected: diesel and gasoline exhaust particles emitted directly from exhaust nozzle, and suspended particulate matter (SPM) near the traffic route. Soxhlet extraction was performed on each sample. By gas-chromatograph-mass spectrometer (GC-MS) analysis of these extracts, di-ethyl phthalate and di- n-butyl phthalate were detected from the extract of SPM and diesel exhaust particles (DEPs). Because these phthalates were sometimes suspected as contamination, time-of-flight secondary ion mass spectrometry (TOF-SIMS) measurements were also performed on the samples collected at the same environment. By comparing obtained spectra, it is clear that these environmental endocrine disrupters (EEDs) were adsorbed on DEP surface. Thus, we concluded that the combination of conventional method and TOF-SIMS measurement is one of the most powerful techniques for analyzing the toxic air pollutants adsorbed on SPM surface.

  1. A Comparative Analysis of Toxicity Models

    DTIC Science & Technology

    2008-04-01

    A-1 B. Selected Gridgen Parameter Values...ranged between 3 and 80 minutes. Agent dispersion was modeled using IDA’s GRIDGEN program, which is a modification of VLSTRACK v. 1.6.3 to give...BioStrike 2 compatible output. The values of some of the parameters used in GRIDGEN are given in Appendix B. GRIDGEN output is in the form of the

  2. Models of Inflammation: Carrageenan Air Pouch.

    PubMed

    Duarte, Djane B; Vasko, Michael R; Fehrenbacher, Jill C

    2016-03-18

    The subcutaneous air pouch is an in vivo model that can be used to study the components of acute and chronic inflammation, the resolution of the inflammatory response, the oxidative stress response, and potential therapeutic targets for treating inflammation. Injection of irritants into an air pouch in rats or mice induces an inflammatory response that can be quantified by the volume of exudate produced, the infiltration of cells, and the release of inflammatory mediators. The model presented in this unit has been extensively used to identify potential anti-inflammatory drugs.

  3. Pyrolysis of polymeric materials. I - Effect of chemical structure, temperature, heating rate, and air flow on char yield and toxicity

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Casey, C. J.

    1979-01-01

    Various polymeric materials, including synthetic polymers and cellulosic materials, were evaluated at different temperatures, heating rates and air flow rates for thermophysical and toxicological responses. It is shown that char yields appeared to be a function of air access as much as of the chemical structure of the material. It is stated that the sensitivity of the apparent thermal stability of some materials to air access is so marked that thermogravimetric studies in oxygen-free atmospheres may be a consistently misleading approach to comparing synthetic polymers intended to increase fire safety. Toxicity also appeared to be a function of temperature and air access as much as of the chemical structure of the material. Toxicity of the gases evolved seemed to increase with increasing char yield for some polymers.

  4. Silent Discharge Plasma Technology for the Treatment of Air Toxics and Other Applications

    SciTech Connect

    Rosocha, Louis A.; Chase, Peter J.; Gross, Michael P.

    1998-09-21

    Under this CRADA, the Los Alamos National Laboratory (LANL) and High Mesa Technologies, Inc. (HMT) carried out a joint project on the development of the silent discharge plasma (SDP) technology for the treatment of hazardous air pollutants and other hazardous or toxic chemicals. The project had two major components: a technology-demonstration part and a scale-up and commercialization part. In the first part, a small-scale, mobile SDP plasma processor, which was being developed under a CRADA with the Electric Power Research Institute (EPRI) was the mobile equipment was modified for higher capacity service and employed for an innovative remediation technologies demonstration on soil-vapor extraction off-gases at the McClellan Air Force Base near Sacramento, CA. The performance of the SDP system for the variety of volatile organic compounds (VOCs) encountered at the McClellan site was sufficiently promising to the project HMT and LANL worked together to formulate a scale-up strategy and commercialization/manufacturing plan, and to design a prototype scaled-up SDP unit. HMT and LANL are now in the final stages of completing a licensing agreement for the technology and HMT is in the process of raising funds to engineer and manufacture commercial prototype SDP equipment focused on stack-gas emissions control and environmental remediation. HMT, in collaboration with another Northern New Mexico business, Coyote Aerospace, has also been successful in receiving a Phase I Small Business Innovative Research (SBIR) award from the Army Research Office to develop, design, and construct a small non-thermal plasma reactor for laboratory studies ("Non-Thermal Plasma Reactor for Control of Fugitive Emissions of Toxic Gases")

  5. Organic toxicants in air and precipitation samples from the Lake Michigan area

    SciTech Connect

    Harlin, K.S.; Sweet, C.W.; Gatz, D.F.

    1995-12-31

    Measurements of PCBs, organochlorine insecticides, PAHs, and atrazine were made in air and precipitation samples collected at regionally-representative locations near Lake Michigan from 1992-1995. The purpose of these measurements was to provide information needed to estimate the atmospheric deposition of organic toxicants to Lake Michigan. Twenty-four hour samples of airborne particles and vapor were collected at 12-day intervals on quartz fiber filters and XAD-2 resin vapor traps using modified high volume sampleers. Twenty-eight day precipitation samples were collected using wet-only samplers with stainless steel sampling surfaces and heated enclosure containing an XAD-2 resin adsorption column. Samples were Soxhlet extracted for 24 hours with hexane:acetone (1:1), and concentrated by rotary evaporation. Interferences were removed and the samples separated into analyte groups by silica gel chromatography. Four fractions were collected for GC-ECD and GC-Ion Trap MS analyses. Ten pesticides, 101 PCB congeners, 18 PAHs, and atrazine were measured in all samples. Quality assurance was maintained by including field duplicate samples, field blanks, alboratory matrix spikes, laboratory matrix blanks, and laboratory surrogate spikes in the sampling/analytical protocols. Preliminary results from urban and remote sites show geographical variations in the concentrations of some toxicants due to contributions from local sources. For all sites the total PCB levels are higher in the vapor phase than the particulate phase and show strong seasonal variations. Seasonal variations were also observed for several pesticides.

  6. Interspecies quantitative structure-toxicity-toxicity (QSTTR) relationship modeling of ionic liquids. Toxicity of ionic liquids to V. fischeri, D. magna and S. vacuolatus.

    PubMed

    Das, Rudra Narayan; Roy, Kunal; Popelier, Paul L A

    2015-12-01

    Considering the increasing uses of ionic liquids (ILs) in various industrial processes and chemical engineering operations, a complete assessment of their hazardous profile is essential. In the absence of adequate experimental data, in silico modeling might be helpful in filling data gaps for the toxicity of ILs towards various ecological indicator organisms. Using the rationale of taxonomic relatedness, the development of predictive quantitative structure-toxicity-toxicity relationship (QSTTR) models allows predicting the toxicity of ILs to a particular species using available experimental toxicity data towards a different species. Such studies may employ, along with the available experimental toxicity data to a species, molecular structure features and physicochemical properties of chemicals as independent variables for prediction of the toxicity profile against another closely related species. A few such interspecies toxicity correlation models have been reported in the literature for diverse chemicals in general, but this approach has been rarely applied to the class of ionic liquids. The present study involves the use of IL toxicity data towards the bacteria Vibrio fischeri along with molecular structure derived information or computational descriptors like extended topochemical atom (ETA) indices, quantum topological molecular similarity (QTMS) descriptors and computed lipophilicity measure (logk0) for the interspecies exploration of the toxicity data towards green algae S. vacuolatus and crustacea Daphnia magna, separately. This modeling study has been performed in accordance with the OECD guidelines. Finally, predictions for a true external set have been performed to fill the data gap of toxicity towards daphnids and algae using the Vibrio toxicity data and molecular structure attributes.

  7. Air Quality Dispersion Modeling - Alternative Models

    EPA Pesticide Factsheets

    Models, not listed in Appendix W, that can be used in regulatory applications with case-by-case justification to the Reviewing Authority as noted in Section 3.2, Use of Alternative Models, in Appendix W.

  8. The cold air drainage model KLAM_21

    NASA Astrophysics Data System (ADS)

    Kossmann, M.

    2010-09-01

    A brief description of the physics and numerical techniques of the cold air drainage model KLAM_21 is presented. The model has been developed by the Deutscher Wetterdienst (Sievers, 2005) for simulations of nocturnal airflow in hilly and mountainous terrain under dry fair weather conditions. The model has been widely used as an environmental consultancy tool. Typical model applications include frost protection (cold air ponding) and air quality (nocturnal ventilation). The single-layer model calculates the depth and the mean wind of a surface based stable layer that evolves from a neutrally stratified atmosphere during nighttime. The prediction of the velocity and direction of the cold air drainage is based on vertically averaged momentum tendency equations. Temporal changes in the total heat deficit in the cold air layer are calculated from a prescribed local heat loss rate (describing turbulent and radiative cooling) and advection (donor-cell algorithm). The depth of the cold air layer (depth of the surface based temperature inversion) is calculated diagnostically from the total heat loss deficit. The model is initialised with neutral stratification at sunset (onset time of nocturnal cooling). Optionally, effects of an ambient (regional) wind and/or the dispersion of a passive tracer can be simulated. Integration over time is carried out on a regular Arakawa C grid using dynamically calculated time steps. Spatial gradients are discretised using centred differential quotients. The standard size of the computational domains can reach up to 1500 x 1500 grid cells. Grid resolutions usually range between 10 m and 500 m. High resolution simulation can be limited to a nested inner grid domain, while the courser outer domain is covering the entire airshed of interest. A friendly user interface allows easy setup, control, and evaluation of model simulations. Some selected examples of KLAM_21 applications are shown to illustrate the features and capabilities of the model

  9. A Bayesian network model for predicting aquatic toxicity mode ...

    EPA Pesticide Factsheets

    The mode of toxic action (MoA) has been recognized as a key determinant of chemical toxicity but MoA classification in aquatic toxicology has been limited. We developed a Bayesian network model to classify aquatic toxicity mode of action using a recently published dataset containing over one thousand chemicals with MoA assignments for aquatic animal toxicity. Two dimensional theoretical chemical descriptors were generated for each chemical using the Toxicity Estimation Software Tool. The model was developed through augmented Markov blanket discovery from the data set with the MoA broad classifications as a target node. From cross validation, the overall precision for the model was 80.2% with a R2 of 0.959. The best precision was for the AChEI MoA (93.5%) where 257 chemicals out of 275 were correctly classified. Model precision was poorest for the reactivity MoA (48.5%) where 48 out of 99 reactive chemicals were correctly classified. Narcosis represented the largest class within the MoA dataset and had a precision and reliability of 80.0%, reflecting the global precision across all of the MoAs. False negatives for narcosis most often fell into electron transport inhibition, neurotoxicity or reactivity MoAs. False negatives for all other MoAs were most often narcosis. A probabilistic sensitivity analysis was undertaken for each MoA to examine the sensitivity to individual and multiple descriptor findings. The results show that the Markov blanket of a structurally

  10. AIR QUALITY MODELING OF AMMONIA: A REGIONAL MODELING PERSPECTIVE

    EPA Science Inventory

    The talk will address the status of modeling of ammonia from a regional modeling perspective, yet the observations and comments should have general applicability. The air quality modeling system components that are central to modeling ammonia will be noted and a perspective on ...

  11. Relationship of Racial Composition and Cancer Risks from Air Toxics Exposure in Memphis, Tennessee, U.S.A.

    PubMed Central

    Jia, Chunrong; James, Wesley; Kedia, Satish

    2014-01-01

    African Americans in the U.S. often live in poverty and segregated urban neighborhoods, many of which have dense industrial facilities resulting in high exposure to harmful air toxics. This study aims to explore the relationship between racial composition and cancer risks from air toxics exposure in Memphis/Shelby County, Tennessee, U.S.A. Air toxics data were obtained from 2005 National Air Toxics Assessment (NATA), and the demographic data, including racial composition, were extracted from the 2000 United States Census. The association was examined using multivariable geographically weighted regression (GWR) analysis. The risk difference between African American and White concentrated areas was defined as the absolute disparity, and the percent difference as the relative disparity. GWR analyses show that cancer risks increase with respect to increasing percent of African Americans at the census tract level. Individuals in African American concentrated tracts bear 6% more cancer risk burden than in White concentrated tracts. The distribution of major roads causes the largest absolute disparity and the distribution of industrial facilities causes the largest relative disparity. Effective strategies for reduction in environmental disparity should especially target sources of large absolute disparities. PMID:25089776

  12. SPATIAL AND TEMPORAL VARIABILITY OF MOBILE SOURCE AIR TOXICS IN THE DETROIT EXPOSURE AND AEROSOL RESEARCH STUDY

    EPA Science Inventory

    Data from the first two years of the Detroit Exposure and Aerosol Research Study (DEARS) were evaluated to determine spatial and temporal characteristics in concentrations of mobile source air toxics (MSATs). Outdoor concentrations of MSATs were significantly higher in samples co...

  13. CHANGES IN HEART RATE VARIABILITY AND LUNG FUNCTION OBSERVED IN NC PATROL TROOPERS EXPOSED TO PM AND AIR TOXICS

    EPA Science Inventory

    Changes in Heart Rate Variability and Lung Function in NC Patrol Troopers exposed to PM and Air Toxics

    Michael Riediker1, Wayne E Cascio1, Robert B Devlin2, Thomas Griggs1&4, Margaret Herbst1, Ronald W Williams3, Steve P McCorquodale4, Philip A Bromberg1
    1) University o...

  14. PREVENTION REFERENCE MANUAL: CONTROL TECHNOLOGIES, VOL. 2. POST-RELEASE MITIGATION MEASURES FOR CONTROLLING ACCIDENTAL RELEASES OF AIR TOXICS

    EPA Science Inventory

    The volume discusses prevention and protection measures for controlling accidental releases of air toxics. The probability of accidental releases depends on the extent to which deviations (in magnitude and duration) in the process can be tolerated before a loss of chemical contai...

  15. Air freight demand models: An overview

    NASA Technical Reports Server (NTRS)

    Dajani, J. S.; Bernstein, G. W.

    1978-01-01

    A survey is presented of some of the approaches which have been considered in freight demand estimation. The few existing continuous time computer simulations of aviation systems are reviewed, with a view toward the assessment of this approach as a tool for structuring air freight studies and for relating the different components of the air freight system. The variety of available data types and sources, without which the calibration, validation and the testing of both modal split and simulation models would be impossible are also reviewed.

  16. Web-Based Toxic Gas Dispersion Model for Shuttle Launch Operations

    NASA Technical Reports Server (NTRS)

    Bardina, Jorge; Thirumalainambi, Rajkumar

    2004-01-01

    During the launch of the Space Shuttle vehicle, the burning of liquid hydrogen fuel with liquid oxygen at extreme high temperatures inside the three space shuttle main engines, and the burning of the solid propellant mixture of ammonium perchlorate oxidizer, aluminum fuel, iron oxide catalyst, polymer binder, and epoxy curing agent in the two solid rocket boosters result in the formation of a large cloud of hot, buoyant toxic exhaust gases near the ground level which subsequently rises and entrains into ambient air until the temperature and density of the cloud reaches an approximate equilibrium with ambient conditions. In this paper, toxic gas dispersion for various gases are simulated over the web for varying environmental conditions which is provided by rawinsonde data. The model simulates chemical concentration at ground level up to 10 miles (1 KM grids) in downrange up to an hour after launch. The ambient concentration of the gas dispersion and the deposition of toxic particles are used as inputs for a human health risk assessment model. The advantage of the present model is the accessibility and dissemination of model results to other NASA centers over the web. The model can be remotely operated and various scenarios can be analyzed.

  17. DESCRIPTION OF ATMOSPHERIC TRANSPORT PROCESSES IN EULERIAN AIR QUALITY MODELS

    EPA Science Inventory

    Key differences among many types of air quality models are the way atmospheric advection and turbulent diffusion processes are treated. Gaussian models use analytical solutions of the advection-diffusion equations. Lagrangian models use a hypothetical air parcel concept effecti...

  18. POLUTE. Forest Air Pollutant Uptake Model

    SciTech Connect

    Murphy, C.E. Jr.; Sinclair, T.R.

    1992-02-13

    POLUTE is a computer model designed to estimate the uptake of air pollutants by forests. The model utilizes submodels to describe atmospheric diffusion immediately above and within the canopy, and into the sink areas within or on the trees. The program implementing the model is general and can be used, with only minor changes, for any gaseous pollutant. The model provides an estimate describing the response of the vegetarian-atmosphere system to the environment as related to three types of processes: atmospheric diffusion, diffusion near and inside the absorbing plant, and the physical and chemical processes at the sink on or within the plant.

  19. Air pollution modeling over Europe using WRFchem

    NASA Astrophysics Data System (ADS)

    Ritter, Mathias; Müller, Mathias

    2010-05-01

    The aim of this study is to model air pollution for entire Switzerland with a very high spatial resolution. For the first time a several year period of air pollution is modeled for entire Switzerland. The high resolution domain of Switzerland is nested into a coarser European domain with a horizontal resolution of 50 km, extending from south of Spain to south of Finland. So far only the framework for the European domain exists and therefore we focus on the method and first results of this particular domain. The state-of-the-art "Weather Research and Forecasting" (WRF) model with a chemistry extension (WRFchem) is used to simulate air pollutants. It is one of the first times that these two "online" coupled models are applied for entire Europe. Gas phase chemistry is modeled with the "Carbon bond mechanism version Z" (CBMZ) with 67 prognostic chemical species and 164 chemical reactions. Aerosols are treated by the "Model for Simulating Aerosol Interactions and Chemistry" (MOSAIC) using 4 sectional aerosol bins. The meteorological initial and boundary conditions are derived from the NCEP Reanalysis 2 and GFS data. The anthropogenic emissions are taken from the European Monitoring and Evaluation Programme (EMEP), which have a horizontal resolution of 50 km and are divided into 11 SNAP-sectors (Selected Nomenclature for reporting of Air Pollutants). According to these different sectors and the countries the data could be disaggregated into hourly emissions according to the GENEMIS project. To use this dataset also a spatial conversion with the inverse next neighbor method and a vertical disaggregation as well as a re-apportioning of different chemical species were applied. Biogenic emissions are computed during runtime using the Guenther Scheme. We noticed that chemical initial conditions are not needed as they are mainly driven by emissions. Hence a spin-up of at least five days is used. For verification purposes correlations with European ground-based measurements (O3

  20. Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilizaton

    SciTech Connect

    David Hassett; Loreal Heebink; Debra Pflughoeft-Hassett; Tera Buckley; Erick Zacher; Mei Xin; Mae Sexauer Gustin; Rob Jung

    2007-03-31

    The University of North Dakota Energy & Environmental Research Center (EERC) conducted a multiyear study to evaluate the impact of mercury and other air toxic elements (ATEs) on the management of coal combustion by-products (CCBs). The ATEs evaluated in this project were arsenic, cadmium, chromium, lead, nickel, and selenium. The study included laboratory tasks to develop measurement techniques for mercury and ATE releases, sample characterization, and release experiments. A field task was also performed to measure mercury releases at a field site. Samples of fly ash and flue gas desulfurization (FGD) materials were collected preferentially from full-scale coal-fired power plants operating both without and with mercury control technologies in place. In some cases, samples from pilot- and bench-scale emission control tests were included in the laboratory studies. Several sets of 'paired' baseline and test fly ash and FGD materials collected during full-scale mercury emission control tests were also included in laboratory evaluations. Samples from mercury emission control tests all contained activated carbon (AC) and some also incorporated a sorbent-enhancing agent (EA). Laboratory release experiments focused on measuring releases of mercury under conditions designed to simulate CCB exposure to water, ambient-temperature air, elevated temperatures, and microbes in both wet and dry conditions. Results of laboratory evaluations indicated that: (1) Mercury and sometimes selenium are collected with AC used for mercury emission control and, therefore, present at higher concentrations than samples collected without mercury emission controls present. (2) Mercury is stable on CCBs collected from systems both without and with mercury emission controls present under most conditions tested, with the exception of vapor-phase releases of mercury exposed to elevated temperatures. (3) The presence of carbon either from added AC or from unburned coal can result in mercury being

  1. Recent Enhancements to the Community Multiscale Air Quality Model (CMAQ)

    EPA Science Inventory

    This presentation overviews recent updates to the CMAQ modeling system. The presentation will be given as part of the information exchange session on Regional Air Pollution Modeling at the UK-US Collaboration Meeting on Air Pollution Exposure Science.

  2. GLOBOX: A spatially differentiated global fate, intake and effect model for toxicity assessment in LCA.

    PubMed

    Wegener Sleeswijk, Anneke; Heijungs, Reinout

    2010-06-15

    GLOBOX is a model for the calculation of spatially differentiated LCA toxicity characterisation factors on a global scale. It can also be used for human and environmental risk assessment. The GLOBOX model contains equations for the calculation of fate, intake and effect factors, and equations for the calculation of LCA characterisation factors for human toxicity and ecotoxicity. The model is differentiated on the level of 239 countries/territories and 50 seas/oceans. Each region has its own set of homogeneous compartments, and the regions are interconnected by atmospheric and aquatic flows. Multimedia transport and degradation calculations are largely based on the EUSES 2.0 multimedia model, and are supplemented by specific equations to account for the advective air and water transport between different countries and/or seas. Metal-specific equations are added to account for speciation in fresh and marine surface water. Distribution parameters for multimedia transport equations are differentiated per country or sea with respect to geographic features, hydrology, and climate. The model has been tested with nitrobenzene as a test chemical, for emissions to all countries in the world. Spatially differentiated characterisation factors turn out to show wide ranges of variation between countries, especially for releases to inland water and soil compartments. Geographic position, distribution of lakes and rivers and variations in environmental temperature and rain rate are decisive parameters for a number of different characterisation factors. Population density and dietary intake play central roles in the variation of characterisation factors for human toxicity. Among the countries that show substantial deviations from average values of the characterisation factors are not only small and remote islands, but also countries with a significant economic production rate, as indicated by their GDPs. It is concluded that spatial differentiation between countries is an important

  3. Toxicity of food-relevant nanoparticles in intestinal epithelial models

    NASA Astrophysics Data System (ADS)

    McCracken, Christie

    Nanoparticles are increasingly being incorporated into common consumer products, including in foods and food packaging, for their unique properties at the nanoscale. Food-grade silica and titania are used as anti-caking and whitening agents, respectively, and these particle size distributions are composed of approximately one-third nanoparticles. Zinc oxide and silver nanoparticles can be used for their antimicrobial properties. However, little is known about the interactions of nanoparticles in the body upon ingestion. This study was performed to investigate the role of nanoparticle characteristics including surface chemistry, dissolution, and material type on toxicity to the intestinal epithelium. Only mild acute toxicity of zinc oxide nanoparticles was observed after 24-hour treatment of intestinal epithelial C2BBe1 cells based on the results of toxicity assays measuring necrosis, apoptosis, membrane damage, and mitochondrial activity. Silica and titanium dioxide nanoparticles were not observed to be toxic although all nanoparticles were internalized by cells. In vitro digestion of nanoparticles in solutions representing the stomach and intestines prior to treatment of cells did not alter nanoparticle toxicity. Long-term repeated treatment of cells weekly for 24 hours with nanoparticles did not change nanoparticle cytotoxicity or the growth rate of the treated cell populations. Thus, silica, titanium dioxide, and zinc oxide nanoparticles were found to induce little toxicity in intestinal epithelial cells. Fluorescent silica nanoparticles were synthesized as a model for silica used in foods that could be tracked in vitro and in vivo. To maintain an exterior of pure silica, a silica shell was hydrolyzed around a core particle of quantum dots or a fluorescent dye electrostatically associated with a commercial silica particle. The quantum dots used were optimized from a previously reported microwave quantum dot synthesis to a quantum yield of 40%. Characterization

  4. VALMET-A valley air pollution model

    SciTech Connect

    Whiteman, C.D.; Allwine, K.J.

    1983-09-01

    Following a thorough analysis of meteorological data obtained from deep valleys of western Colorado, a modular air-pollution model has been developed to simulate the transport and diffusion of pollutants released from an elevated point source in a well-defined mountain valley during the nighttime and morning transition periods. This initial version of the model, named VALMET, operates on a valley cross section at an arbitrary distance down-valley from a continuous point source. The model has been constructed to include parameterizations of the major physical processes that act to disperse pollution during these time periods. The model has not been fully evaluated. Further testing, evaluations, and development of the model are needed. Priorities for further development and testing are provided.

  5. Phenomenological model of nuclear primary air showers

    NASA Technical Reports Server (NTRS)

    Tompkins, D. R., Jr.; Saterlie, S. F.

    1976-01-01

    The development of proton primary air showers is described in terms of a model based on a hadron core plus an electromagnetic cascade. The muon component is neglected. The model uses three parameters: a rate at which hadron core energy is converted into electromagnetic cascade energy and a two-parameter sea-level shower-age function. By assuming an interaction length for the primary nucleus, the model is extended to nuclear primaries. Both models are applied over the energy range from 10 to the 13th power to 10 to the 21st power eV. Both models describe the size and age structure (neglecting muons) from a depth of 342 to 2052 g/sq cm.

  6. The Air Quality Model Evaluation International Initiative ...

    EPA Pesticide Factsheets

    This presentation provides an overview of the Air Quality Model Evaluation International Initiative (AQMEII). It contains a synopsis of the three phases of AQMEII, including objectives, logistics, and timelines. It also provides a number of examples of analyses conducted through AQMEII with a particular focus on past and future analyses of deposition. The National Exposure Research Laboratory (NERL) Computational Exposure Division (CED) develops and evaluates data, decision-support tools, and models to be applied to media-specific or receptor-specific problem areas. CED uses modeling-based approaches to characterize exposures, evaluate fate and transport, and support environmental diagnostics/forensics with input from multiple data sources. It also develops media- and receptor-specific models, process models, and decision support tools for use both within and outside of EPA.

  7. Air and seawater pollution and air-sea gas exchange of persistent toxic substances in the Aegean Sea: spatial trends of PAHs, PCBs, OCPs and PBDEs.

    PubMed

    Lammel, Gerhard; Audy, Ondřej; Besis, Athanasios; Efstathiou, Christos; Eleftheriadis, Kostas; Kohoutek, Jiři; Kukučka, Petr; Mulder, Marie D; Přibylová, Petra; Prokeš, Roman; Rusina, Tatsiana P; Samara, Constantini; Sofuoglu, Aysun; Sofuoglu, Sait C; Taşdemir, Yücel; Vassilatou, Vassiliki; Voutsa, Dimitra; Vrana, Branislav

    2015-08-01

    Near-ground air (26 substances) and surface seawater (55 substances) concentrations of persistent toxic substances (PTS) were determined in July 2012 in a coordinated and coherent way around the Aegean Sea based on passive air (10 sites in 5 areas) and water (4 sites in 2 areas) sampling. The direction of air-sea exchange was determined for 18 PTS. Identical samplers were deployed at all sites and were analysed at one laboratory. hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs) as well as dichlorodiphenyltrichloroethane (DDT) and its degradation products are evenly distributed in the air of the whole region. Air concentrations of p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and o,p'-DDT and seawater concentrations of p,p'-DDE and p,p'-DDD were elevated in Thermaikos Gulf, northwestern Aegean Sea. The polychlorinated biphenyl (PCB) congener pattern in air is identical throughout the region, while polybrominated diphenylether (PBDE)patterns are obviously dissimilar between Greece and Turkey. Various pollutants, polycyclic aromatic hydrocarbons (PAHs), PCBs, DDE, and penta- and hexachlorobenzene are found close to phase equilibrium or net-volatilisational (upward flux), similarly at a remote site (on Crete) and in the more polluted Thermaikos Gulf. The results suggest that effective passive air sampling volumes may not be representative across sites when PAHs significantly partitioning to the particulate phase are included.

  8. 77 FR 4808 - Conference on Air Quality Modeling

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-31

    ... AGENCY Conference on Air Quality Modeling AGENCY: U.S. Environmental Protection Agency (EPA). ACTION: Notice of conference. SUMMARY: The EPA will be hosting the Tenth Conference on Air Quality Modeling on... preferred air quality models and to provide a forum for public review and comment on how the...

  9. Air Pollution Data for Model Evaluation and Application

    EPA Science Inventory

    One objective of designing an air pollution monitoring network is to obtain data for evaluating air quality models that are used in the air quality management process and scientific discovery.1.2 A common use is to relate emissions to air quality, including assessing ...

  10. Intermedia transfer factors for fifteen toxic pollutants released to air basins in California

    SciTech Connect

    McKone, T.E.; Daniels, J.I.; Chiao, F.F.; Hsieh, D.P.H.

    1993-10-01

    This report provides a summary definition of the intermedia-transfer factors (ITFs). Methods are discussed for estimating these parameters in the absence of measured values, and the estimation errors inherent in these estimation methods are considered. A detailed summary is provided of measured and estimated ITF values for fifteen air contaminants. They include: 1,3 butadiene; cadmium; cellosolve; cellosolve acetate; chloroform; di-2-ethylhexylphthalate; 1,4-dioxame; hexachlorobenzene; inorganic arsenic; inorganic lead; nickel; tetrachloroethylene; toluene; toluene-2,4-diisocyanate; and 1,3-xylene. Recommendations are made regarding the expected value and variance in these values for use in exposure models.

  11. High content analysis of an in vitro model for metabolic toxicity: results with the model toxicants 4-aminophenol and cyclophosphamide.

    PubMed

    Cole, Stephanie D; Madren-Whalley, Janna S; Li, Albert P; Dorsey, Russell; Salem, Harry

    2014-12-01

    In vitro models that accurately and rapidly assess hepatotoxicity and the effects of hepatic metabolism on nonliver cell types are needed by the U.S. Department of Defense and the pharmaceutical industry to screen compound libraries. Here, we report the first use of high content analysis on the Integrated Discrete Multiple Organ Co-Culture (IdMOC) system, a high-throughput method for such studies. We cultured 3T3-L1 cells in the presence and absence of primary human hepatocytes, and exposed the cultures to 4-aminophenol and cyclophosphamide, model toxicants that are respectively detoxified and activated by the liver. Following staining with calcein-AM, ethidium homodimer-1, and Hoechst 33342, high content analysis of the cultures revealed four cytotoxic endpoints: fluorescence intensities of calcein-AM and ethidium homodimer-1, nuclear area, and cell density. Using these endpoints, we observed that the cytotoxicity of 4-aminophenol in 3T3-L1 cells in co-culture was less than that observed for 3T3-L1 monocultures, consistent with the known detoxification of 4-aminophenol by hepatocytes. Conversely, cyclophosphamide cytotoxicity for 3T3-L1 cells was enhanced by co-culturing with hepatocytes, consistent with the known metabolic activation of this toxicant. The use of IdMOC plates combined with high content analysis is therefore a multi-endpoint, high-throughput capability for measuring the effects of metabolism on toxicity.

  12. Transcriptomic responses of European flounder (Platichthys flesus) to model toxicants.

    PubMed

    Williams, Tim D; Diab, Amer; Ortega, Fernando; Sabine, Victoria S; Godfrey, Rita E; Falciani, Francesco; Chipman, J Kevin; George, Stephen G

    2008-11-11

    The temporal transcriptomic responses in liver of Platichthys flesus to model environmental pollutants were studied over a 16-day time span after intraperitoneal injection with cadmium chloride (50 microg/kg in saline), 3-methylcholanthrene (25 mg/kg in olive oil), Aroclor 1254 (50 mg/kg in olive oil), tert-butyl-hydroperoxide (5 mg/kg in saline), Lindane (25mg/kg in olive oil), perfluoro-octanoic acid (100 mg/kg in olive oil) and their vehicles, olive oil (1 ml/kg) or saline (0.9%). Statistical, gene ontology and supervised analysis clearly demonstrated the progression from acute effects, biological responses to and recovery from the treatments. Key biological processes disturbed by the individual treatments were characterised by gene ontology analyses and individual toxicant-responsive genes and pathways were identified by supervised analyses. Responses to the polyaromatic and chlorinated aromatic compounds showed a degree of commonality but were distinguishable and they were clearly segregated from the responses to the pro-oxidants cadmium and the organic hydroperoxide, as well as from the peroxisomal proliferator, perfluoro-octanoic acid. This study demonstrated the utility of the microarray technique in the identification of toxicant-responsive genes and in discrimination between modes of toxicant action.

  13. In Utero and Early-Life Exposure to Ambient Air Toxics and Childhood Brain Tumors: A Population-Based Case–Control Study in California, USA

    PubMed Central

    von Ehrenstein, Ondine S.; Heck, Julia E.; Park, Andrew S.; Cockburn, Myles; Escobedo, Loraine; Ritz, Beate

    2015-01-01

    Background: Little is known about the influence of environmental factors on the etiology of childhood brain tumors. Objectives: We examined risks for brain tumors in children after prenatal and infant exposure to monitored ambient air toxics. Methods: We ascertained all cases of medulloblastoma, central nervous system primitive neuroectodermal tumor (PNET), and astrocytoma before 6 years of age diagnosed in 1990–2007 from the California Cancer Registry and selected controls randomly from birth rolls matched by birth year. Exposures to air toxics during pregnancy/infancy for 43 PNET, 34 medulloblastoma, and 106 astrocytoma cases and 30,569 controls living within 5 mi of a monitor were determined. With factor analysis we assessed the correlational structures of 26 probable carcinogenic toxics, and estimated odds ratios by brain tumor type in logistic regression models. Results: PNETs (≤ 38 cases) were positively associated with interquartile range (IQR) increases in prenatal exposure to acetaldehyde [odds ratio (OR) = 2.30; 95% CI: 1.44, 3.67], 1,3-butadiene (OR = 2.23; 95% CI: 1.28, 3.88), benzene, and toluene; and with IQR increases in exposure during the first year of life to ortho-dichlorobenzene (OR = 3.27; 95% CI: 1.17, 9.14), 1,3-butadiene (OR = 3.15; 95% CI: 1.57, 6.32), and benzene. All exposures except ortho-dichlorobenzene loaded on the same factor. Medulloblastoma (≤ 30 cases) was associated with prenatal exposure to polycyclic aromatic hydrocarbons (PAHs combined: OR = 1.44; 95% CI: 1.15, 1.80). Exposures to lead and some PAHs during the first year of life were positively associated with astrocytoma, but the confidence intervals included the null value (e.g., for lead, OR = 1.40; 95% CI: 0.97, 2.03). Conclusions: Our data suggest that in utero and infancy exposures to air toxics generated by industrial and road traffic sources may increase the risk of PNET and medulloblastoma, with limited support for increased risks for astrocytoma in children up

  14. Toxic releases and risk disparity: a spatiotemporal model of industrial ecology and social empowerment.

    PubMed

    Aoyagi, Hannah; Ogunseitan, Oladele A

    2015-06-02

    Information-based regulations (IBRs) are founded on the theoretical premise that public participation in accomplishing policy goals is empowered by open access to information. Since its inception in 1988, the Toxics Release Inventory (TRI) has provided the framework and regulatory impetus for the compilation and distribution of data on toxic releases associated with industrial development, following the tenets of IBR. As TRI emissions are reputed to disproportionately affect low-income communities, we investigated how demographic characteristics are related to change in TRI emissions and toxicity risks between 1989 and 2002, and we sought to identify factors that predict these changes. We used local indicators of spatial association (LISA) maps and spatial regression techniques to study risk disparity in the Los Angeles urban area. We also surveyed 203 individuals in eight communities in the same region to measure the levels of awareness of TRI, attitudes towards air pollution, and general environmental risk. We discovered, through spatial lag models, that changes in gross and toxic emissions are related to community ethnic composition, poverty level, home ownership, and base 1989 emissions (R-square=0.034-0.083). We generated a structural equation model to explain the determinants of social empowerment to act on the basis of environmental information. Hierarchical confirmatory factor analysis (HCFA) supports the theoretical model that individual empowerment is predicted by risk perception, worry, and awareness (Chi-square=63.315, p=0.022, df=42). This study provides strong evidence that spatiotemporal changes in regional-scale environmental risks are influenced by individual-scale empowerment mediated by IBRs.

  15. CMAQ Involvement in Air Quality Model Evaluation International Initiative

    EPA Pesticide Factsheets

    Description of Air Quality Model Evaluation International Initiative (AQMEII). Different chemical transport models are applied by different groups over North America and Europe and evaluated against observations.

  16. Assessment of toxicity of nanoparticles using insects as biological models.

    PubMed

    Zhou, Yan; Rocha, Aracely; Sanchez, Carlos J; Liang, Hong

    2012-01-01

    Nanomaterials have become increasingly important in medicine, manufacturing, and consumer products. The fundamental understanding in effects of nanoparticles (NPs) on and their interactions with biomolecules and organismal systems have yet to be achieved. In this chapter, we firstly provide a brief review of the interactions between nanoparticles and biological systems. We will then provide an example by describing a novel method to assess the effects of NPs on biological systems, using insects as a model. Nanoparticles were injected into the central nervous system of the discoid cockroach (Blaberus discoidalis). It was found that insects became hyperactive compared to negative control (water injections). Our method could provide a generic method of assessing nanoparticles toxicity.

  17. Thermal Stress and Toxicity

    EPA Science Inventory

    Elevating ambient temperature above thermoneutrality exacerbates toxicity of most air pollutants, insecticides, and other toxic chemicals. On the other hand, safety and toxicity testing of toxicants and drugs is usually performed in mice and rats maintained at subthermoneutral te...

  18. MOAtox: A Comprehensive Mode of Action and Acute Aquatic Toxicity Database for Predictive Model Development

    EPA Science Inventory

    tThe mode of toxic action (MOA) has been recognized as a key determinant of chemical toxicity andas an alternative to chemical class-based predictive toxicity modeling. However, the development ofquantitative structure activity relationship (QSAR) and other models has been limite...

  19. Workbook of screening techniques for assessing impacts of toxic air pollutants (revised). Final report

    SciTech Connect

    Not Available

    1992-12-01

    The workbook provides a logical approach to the selection of appropriate screening techniques for estimating ambient concentrations due to various toxic/hazardous pollutant releases. Methods used in the workbook apply to situations where a release can be fairly well-defined, a condition typically associated with non-accidental toxic releases. The format of the workbook is built around a series of release scenarios which may be considered typical and representative of the means by which toxic chemicals become airborne.

  20. Organophosphates, serine esterase inhibition, and modeling of organophosphate toxicity.

    PubMed

    Chambers, Janice; Oppenheimer, Seth F

    2004-02-01

    The highlighted article in this issue (Ashani and Pistinner, "Estimation of the Upper Limit of Human Butyrylcholinesterase Dose Required for Protection against Organophosphates toxicity: A Mathematically Based Toxicokinetic Model") is an innovative approach to modeling the amount of protective enzyme, human butyrylcholinesterase, that could be administered to humans to protect them from the lethal effects of organophosphate nerve agents. The threat of nerve agent exposures at lethal level regrettably remains a threat to military as well civilian populations, and the authors of this article have used their previous experimental data along with new in vitro data to devise and calibrate a mathematical model that could have practical utility in the prophylaxis of military personnel against chemical warfare agents.

  1. Identifying developmental vascular disruptor compounds using a predictive signature and alternative toxicity models

    EPA Science Inventory

    Identifying Developmental Vascular Disruptor Compounds Using a Predictive Signature and Alternative Toxicity Models Presenting Author: Tamara Tal Affiliation: U.S. EPA/ORD/ISTD, RTP, NC, USA Chemically induced vascular toxicity during embryonic development can result in a wide...

  2. Prediction Models are Basis for Rational Air Quality Control

    ERIC Educational Resources Information Center

    Daniels, Anders; Bach, Wilfrid

    1973-01-01

    An air quality control scheme employing meteorological diffusion, time averaging and frequency, and cost-benefit models is discussed. The methods outlined provide a constant feedback system for air quality control. Flow charts and maps are included. (BL)

  3. Indoor Air Quality Building Education and Assessment Model

    EPA Pesticide Factsheets

    The Indoor Air Quality Building Education and Assessment Model (I-BEAM), released in 2002, is a guidance tool designed for use by building professionals and others interested in indoor air quality in commercial buildings.

  4. Indoor Air Quality Building Education and Assessment Model Forms

    EPA Pesticide Factsheets

    The Indoor Air Quality Building Education and Assessment Model (I-BEAM) is a guidance tool designed for use by building professionals and others interested in indoor air quality in commercial buildings.

  5. Exposure Modeling of Residential Air Exchange Rates for NEXUS Participants.

    EPA Science Inventory

    Due to cost and participant burden of personal measurements, air pollution health studies often estimate exposures using local ambient air monitors. Since outdoor levels do not necessarily reflect personal exposures, we developed the Exposure Model for Individuals (EMI) to improv...

  6. Exposure Modeling of Residential Air Exchange Rates for NEXUS Participants

    EPA Science Inventory

    Due to cost and participant burden of personal measurements, air pollution health studies often estimate exposures using local ambient air monitors. Since outdoor levels do not necessarily reflect personal exposures, we developed the Exposure Model for Individuals (EMI) to improv...

  7. A model to predict rate of dissolution of toxic compounds into seawater from an oil spill.

    PubMed

    Riazi, M R; Roomi, Y A

    2008-01-01

    In this paper a semianalytical model has been proposed to predict the rate at which oil components dissolve in water when an oil spill occurs in a marine environment. The model breaks the oil into a number of pseudocomponents proportional to the number of compounds originally present in the oil and calculates the rate of dissolution for each component. In addition, the components are divided into paraffinic, naphthenic, and aromatic hydrocarbon types and the amount of dissolution of each pseudocomponent is calculated versus time. In this method the concentration of most toxic components of oil (mainly monoaromatics) is determined. The model considers variable surface area and slick thickness and requires oil specifications (i.e., American Petroleum Institute [API] gravity and boiling point) in addition to air and water temperatures and speeds. The model has been applied to a Kuwaiti crude oil and its products naphtha and kerosene samples at 20 degrees C and 40 degrees C. The results could be useful in selection of an appropriate method for oil spill clean up as well as simulation of environmental impact of oil spill from toxicity points of view.

  8. In vitro toxicity testing of cigarette smoke based on the air-liquid interface exposure: A review.

    PubMed

    Li, Xiang

    2016-10-01

    Cigarette smoke is a complex aerosol comprising particulate phase and gaseous vapour phase. The air-liquid interface exposure provides a possible technical means to implement whole smoke exposure for the assessment of tobacco products. In this review, the research progress in the in vitro toxicity testing of cigarette smoke based on the air-liquid interface exposure is summarized. The contents presented involve mainly cytotoxicity, genotoxicity, oxidative stress, inflammation, systems toxicology, 3D culture and cigarette smoke dosimetry related to cigarette smoke, as well as the assessment of electronic cigarette aerosol. Prospect of the application of the air-liquid interface exposure method in assessing the biological effects of tobacco smoke is discussed.

  9. Paraquat toxicity in a mouse embryonic stem cell model.

    PubMed

    Perla, Venu; Perrin, Nancy A; Greenlee, Anne R

    2008-03-01

    The objective of this in vitro study was to use a mouse embryonic stem (mES) cell model to better understand pesticide injury that may adversely affect early pregnancy and to evaluate an antioxidant intervention. Undifferentiated D3 mES cells were incubated 24h with control, reference dose (RfD), no observed effect level (NOEL), or lowest observed effect level (LOEL) of paraquat, a commonly used, toxic agricultural herbicide. Pesticide effects were evaluated at 0 and 24h using assays for cell proliferation, total reactive oxygen species (ROS), viability, and alkaline phosphatase activity. Compared to 0 h, cell proliferation increased significantly in the 24h control treatment and was stalled in all paraquat dilutions tested. ROS production and percent necrotic and apoptotic cells were significantly increased at all paraquat concentrations examined. Alkaline phosphatase activity suggested that cells remained undifferentiated during the study period. Experiments with ascorbic acid suggested that pesticide effects on cell viability and ROS production were minimized by the recommended daily allowance (RDA) of vitamin C. Data suggest pesticide-induced injury can occur very early in development and at concentrations predicted without health consequences. Mouse ES cells may provide a useful in vitro model for rapidly screening developmental toxicants and protective interventions.

  10. Fact Sheet - Final Air Toxics Rule for Gold Mine Ore Processing and Production

    EPA Pesticide Factsheets

    Fact sheet summarizing main points of National Emissions Standards for Hazardous Air Pollutants for gold ore processing and production facilities, the seventh largest source of mercury air emission in the United States.

  11. Ultra High Efficiency ESP for Fine Particulate and Air Toxics Control

    SciTech Connect

    Srinivasachar, Srivats; Pease, Benjamin R.; Porle, Kjell; Mauritzson, Christer; Haythornthwaite, Sheila

    1997-07-01

    Nearly ninety percent of U.S. coal-fired utility boilers are equipped with electrostatic precipitators (ESP). Cost effective retrofittable ESP technologies are the only means to accomplish Department of Energy's (DOE) goal of a major reduction in fine particulate and air toxic emissions from coal-fired power plants. Particles in the size range of 0.1 to 5 {micro}m typically escape ESPs. Metals, such as arsenic, cadmium, lead, molybdenum and antimony, concentrate on these particles. This is the main driver for improved fine particulate control. Vapor phase emissions of mercury, selenium and arsenic are also of major concern. Current dry ESPs, which operate at temperatures greater than 280 F, provide little control for vapor phase toxics. The need for inherent improvement to ESPs has to be considered keeping in perspective the current trend towards the use of low sulfur coals. Switching to low sulfur coals is the dominant approach for SO{sub 2} emission reduction in the utility industry. Low sulfur coals generate high resistivity ash, which can cause an undesirable phenomenon called ''back corona.'' Higher particulate emissions occur if there is back corona in the ESP. Results of the pilot-scale testing identified the ''low temperature ESP'' concept to have the biggest impact for the two low sulfur coals investigated. Lowering the flue gas temperature to 220 F provided the maximum impact in terms of decreased emissions. Intermediate operating temperatures (reduction from 340 to 270 F) also gave significant ESP performance improvement. A significant reduction in particulate emissions was also noted when the flue gas humidity was increased (temperature held constant) from the baseline condition for these moderately high resistivity ash coals. Independent control of flue gas humidity and temperature was an important and a notable element in this project. Mercury emissions were also measured as a function of flue gas temperature. Mercury emissions decreased as the flue

  12. Augmenting aquatic species sensitivity distributions with interspecies toxicity estimation models

    EPA Science Inventory

    Species sensitivity distributions (SSD) are cumulative distribution functions of species toxicity values. The SSD approach is increasingly being used in ecological risk assessment, but is often limited by available toxicity data necessary for diverse species representation. In ...

  13. Nutritional influences on metal toxicity: cadmium as a model toxic element.

    PubMed Central

    Fox, M R

    1979-01-01

    The nutrient quality of the diet has been shown repeatedly to be a significant factor in modifying the response of man and animals to toxic element exposure. Deficiencies of several essential nutrients have been shown to exacerbate the effects of cadmium and supplements of such nutrients have been shown to ameliorate the toxicity. Thus the effects of exposure to a toxic element, such as cadmium, may vary, depending on interactions with other elements which are present in the diet in different concentrations. PMID:510248

  14. Organotypic liver culture models: Meeting current challenges in toxicity testing

    PubMed Central

    LeCluyse, Edward L.; Witek, Rafal P.; Andersen, Melvin E.; Powers, Mark J.

    2012-01-01

    Prediction of chemical-induced hepatotoxicity in humans from in vitro data continues to be a significant challenge for the pharmaceutical and chemical industries. Generally, conventional in vitro hepatic model systems (i.e. 2-D static monocultures of primary or immortalized hepatocytes) are limited by their inability to maintain histotypic and phenotypic characteristics over time in culture, including stable expression of clearance and bioactivation pathways, as well as complex adaptive responses to chemical exposure. These systems are less than ideal for longer-term toxicity evaluations and elucidation of key cellular and molecular events involved in primary and secondary adaptation to chemical exposure, or for identification of important mediators of inflammation, proliferation and apoptosis. Progress in implementing a more effective strategy for in vitro-in vivo extrapolation and human risk assessment depends on significant advances in tissue culture technology and increasing their level of biological complexity. This article describes the current and ongoing need for more relevant, organotypic in vitro surrogate systems of human liver and recent efforts to recreate the multicellular architecture and hemodynamic properties of the liver using novel culture platforms. As these systems become more widely used for chemical and drug toxicity testing, there will be a corresponding need to establish standardized testing conditions, endpoint analyses and acceptance criteria. In the future, a balanced approach between sample throughput and biological relevance should provide better in vitro tools that are complementary with animal testing and assist in conducting more predictive human risk assessment. PMID:22582993

  15. Animal Models of Peripheral Neuropathy Due to Environmental Toxicants

    PubMed Central

    Rao, Deepa B.; Jortner, Bernard S.; Sills, Robert C.

    2014-01-01

    Despite the progress in our understanding of pathogeneses and the identification of etiologies of peripheral neuropathy, idiopathic neuropathy remains common. Typically, attention to peripheral neuropathies resulting from exposure to environmental agents is limited relative to more commonly diagnosed causes of peripheral neuropathy (diabetes and chemotherapeutic agents). Given that there are more than 80,000 chemicals in commerce registered with the Environmental Protection Agency and that at least 1000 chemicals are known to have neurotoxic potential, very few chemicals have been established to affect the peripheral nervous system (mainly after occupational exposures). A wide spectrum of exposures, including pesticides, metals, solvents, nutritional sources, and pharmaceutical agents, has been related, both historically and recently, to environmental toxicant-induced peripheral neuropathy. A review of the literature shows that the toxicity and pathogeneses of chemicals adversely affecting the peripheral nervous system have been studied using animal models. This article includes an overview of five prototypical environmental agents known to cause peripheral neuropathy—namely, organophosphates, carbon disulfide, pyridoxine (Vitamin B6), acrylamide, and hexacarbons (mainly n-hexane, 2,5-hexanedione, methyl n-butyl ketone). Also included is a brief introduction to the structural components of the peripheral nervous system and pointers on common methodologies for histopathologic evaluation of the peripheral nerves. PMID:24615445

  16. 40 CFR Table 4 to Subpart Dddd of... - Model Rule-Toxic Equivalency Factors

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 6 2011-07-01 2011-07-01 false Model Rule-Toxic Equivalency Factors 4... Compliance Times for Commercial and Industrial Solid Waste Incineration Units that Commenced Construction On... Rule—Toxic Equivalency Factors Dioxin/furan congener Toxic equivalency factor...

  17. 40 CFR Table 4 to Subpart Dddd of... - Model Rule-Toxic Equivalency Factors

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Model Rule-Toxic Equivalency Factors 4... Compliance Times for Commercial and Industrial Solid Waste Incineration Units that Commenced Construction On... Rule—Toxic Equivalency Factors Dioxin/furan congener Toxic equivalency factor...

  18. Estimation of Wildlife Hazard Levels Using Interspecies Correlation Models and Standard Laboratory Rodent Toxicity Data

    EPA Science Inventory

    Toxicity data from laboratory rodents are widely available and frequently used in human health assessments as an animal model. We explore the possibility of using single rodent acute toxicity values to predict chemical toxicity to a diversity of wildlife species and to estimate ...

  19. 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

  20. 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

  1. On Regional Modeling to Support Air Quality Policies

    EPA Science Inventory

    We examine the use of the Community Multiscale Air Quality (CMAQ) model in simulating the changes in the extreme values of air quality that are of interest to the regulatory agencies. Year-to-year changes in ozone air quality are attributable to variations in the prevailing mete...

  2. Personal exposures, indoor-outdoor relationships, and breath levels of toxic air pollutants measured for 355 persons in New Jersey

    NASA Astrophysics Data System (ADS)

    Wallace, Lance A.; Pellizzari, Edo D.; Hartwell, Ty D.; Sparacino, Charles M.; Sheldon, Linda S.; Zelon, Harvey

    EPA's TEAM Study has measured exposures to 20 volatile organic compounds in personal air, outdoor air, drinking water and the breath of 355 persons in NJ, in the fall of 1981. The NJ residents were selected by a probability sampling scheme to represent 128,000 inhabitants of Elizabeth and Bayonne. Participants carried a personal monitor to collect two 12-h air samples and gave a breath sample at the end of the day. Two consecutive 12-h outdoor air samples were also collected on identical Tenax cartridges in the back yards of 90 of the participants. About 3000 samples were collected, of which 1000 were quality control samples. Eleven compounds were often present in air. Personal exposures were consistently higher than outdoor concentrations for these chemicals, and were sometimes ten times the outdoor concentrations. Indoor sources appeared responsible for much of the difference. Breath concentrations also usually exceed outdoor concentrations, and correlated more strongly with personal exposures than with outdoor concentrations. Some activities (smoking, driving, visiting dry cleaners or service stations) and occupations (chemical, paint and plastics plants) were associated with significantly elevated exposures and breath levels for certain toxic chemicals.

  3. Reduced Toxicity, High Performance Monopropellant at the U.S. Air Force Research Laboratory

    DTIC Science & Technology

    2010-04-27

    sensitivity, stability, and toxicity studies have been conducted on the monopropellant and will be described. The results from AF-M315E indicate that a...hydrazine monopropellant for spacecraft propulsion. Hazard and safety/sensitivity, stability, and toxicity studies have been conducted on the...and development. During the 1940s and 1950s efforts focused on evaluations of monopropellants such as hydrogen peroxide, propyl nitrate, ethylene

  4. Wet air oxidation pretreatment of biomethanated distillery effluent: mapping pretreatment efficiency in terms color, toxicity reduction and biogas generation.

    PubMed

    Sarat Chandra, T; Malik, S N; Suvidha, G; Padmere, M L; Shanmugam, P; Mudliar, S N

    2014-04-01

    The effluents from molasses-based distilleries after biomethanation are beset with problems of intensified dark brown color, high residual COD, low biodegradability index (BOD/COD ratio <0.2) and toxicity issues for possible land application as a potential fertilizer. Wet air oxidation (WAO) pretreatment of biomethanated distillery effluent resulted in substantial enhancement in the biodegradability index (BI) (up to 0.8). WAO pretreated effluent on anaerobic digestion indicated favorable biogas generation with methane content up to 64% along with concomitant COD reduction up to 54.75%. The HPLC analysis indicated that the pretreatment facilitated degradation of major color containing compounds-namely melanoidins, up to 97.8%. The pretreated effluent with enhanced biodegradability along with substantially reduced color also indicated positive effect on seed germination (up to 100%), implying toxicity reduction of the effluent post WAO pretreatment.

  5. Fact Sheet - Final Amendments to Air Toxics Rule for Miscellaneous Coating Manufacturing

    EPA Pesticide Factsheets

    Fact sheet answering questions concerning National Emission Standards for Hazardous Air Pollutants for Miscellaneous Coating Manufacturing which includes facilities that produce inks, paints and adhesives.

  6. Impact of inherent meteorology uncertainty on air quality model predictions

    EPA Science Inventory

    It is well established that there are a number of different classifications and sources of uncertainties in environmental modeling systems. Air quality models rely on two key inputs, namely, meteorology and emissions. When using air quality models for decision making, it is impor...

  7. Landfill Air Emissions Estimation Model, Version 1. 1. User's manual. Final report

    SciTech Connect

    Pelt, W.R.; Bass, R.L.; Kuo, I.R.; Blackard, A.L.

    1991-04-01

    The document is a user's guide for the computer program, Landfill Air Emissions Estimation Model. It provides step-by-step guidance for using the program to estimate landfill air emissions. The purpose of the program is to aid local and state agencies in estimating landfill air emission rates for nonmethane organic compounds and individual air toxics. The program will also be helpful to landfill owners and operators affected by the upcoming New Source Performance Standard (NSPS) and Emission Guidelines for Municipal Solid Waste Landfill Air Emissions. The model is based on the Scholl Canyon Gas Generation Model, used in the development of the soon-to-be-proposed regulation for landfill air emissions. The Scholl Canyon Model is a first order decay equation that uses site-specific characteristics for estimating the gas generation rate. In the absence of site-specific data, the program provides conservative default values from the soon-to-be-proposed NSPS for new landfills and emission guidelines for existing landfills. These default values may be revised based on future information collected by the Agency.

  8. "Air Toxics under the Big Sky": Examining the Effectiveness of Authentic Scientific Research on High School Students' Science Skills and Interest

    ERIC Educational Resources Information Center

    Ward, Tony J.; Delaloye, Naomi; Adams, Earle Raymond; Ware, Desirae; Vanek, Diana; Knuth, Randy; Hester, Carolyn Laurie; Marra, Nancy Noel; Holian, Andrij

    2016-01-01

    "Air Toxics Under the Big Sky" is an environmental science outreach/education program that incorporates the Next Generation Science Standards (NGSS) 8 Practices with the goal of promoting knowledge and understanding of authentic scientific research in high school classrooms through air quality research. This research explored: (1)…

  9. PRELIMINARY FINDINGS ON THE ASSESSMENT OF POTENTIAL CAR-RELATED OCCUPATIONAL PM AND AIR TOXIC EXPOSURE TO PATROL TROOPERS (COPP STUDY)

    EPA Science Inventory

    In-vehicle, roadside and community-based measurements of particulate matter (PM) and select air toxics were measured as part of a study involving patrol cars from the North Carolina Highway Patrol. One goal of this study was to characterize PM and related air pollutant concentra...

  10. [Comparison of four multivariate calibration methods in simultaneous determination of air toxic organic compounds with FTIR spectroscopy].

    PubMed

    Li, Yan; Wang, Jun-de; Chen, Zuo-ru; Zhou, Xue-tie; Huang, Zhong-hua

    2002-10-01

    The concentration determination abilities of four multivariate calibration methods--classical least squares (CLS), partial least squares (PLS), kalman filter method (KFM) and artificial neural network (ANN) were compared in this paper. Five air toxic organic compounds--1,3-butadiene, benzene, o-xylen, chlorobenzene, and acrolein--whose FTIR spectra seriously overlap each other were selected to compose the analytical objects. The evaluation criterion was according to the mean prediction error (MPE) and mean relative error (MRE). Results showed that PLS was superior to other methods when treating multicomponent analysis problem, while there was no comparable difference between CLS, KFM and ANN.

  11. Modeling activities in air traffic control systems: antecedents and consequences of a mid-air collision.

    PubMed

    de Carvalho, Paulo Victor R; Ferreira, Bemildo

    2012-01-01

    In this article we present a model of some functions and activities of the Brazilian Air traffic Control System (ATS) in the period in which occurred a mid-air collision between flight GLO1907, a commercial aircraft Boeing 737-800, and flight N600XL, an executive jet EMBRAER E-145, to investigate key resilience characteristics of the ATM. Modeling in some detail activities during the collision and related them to overall behavior and antecedents that stress the organization uncover some drift into failure mechanisms that erode safety defenses provided by the Air Navigation Service Provider (ANSP), enabling a mid-air collision to be happen.

  12. Dietary and Pharmacological Intervention to Mitigate the Cardiopulmonary Effects of Air Pollution Toxicity

    EPA Science Inventory

    Background: Human exposure to air pollution has long been associated with excess morbidity and mortality. Although regulatory measures carried out under the “Clean Air Act” have saved millions of lives, there are still hundreds of thousands of people in the U.S. that live in area...

  13. Toxic treatments 'in-situ' steam/hot-air stripping technology. Applications analysis report. Rept. for Jun 89-Jun 90

    SciTech Connect

    Jackson, T.

    1991-03-01

    A SITE Demonstration of the Toxic Treatment (USA) Inc. in-situ steam/hot-air stripping technology (Detoxifier) was conducted beginning in the fall of 1989 at the GATX Annex Terminal site located in San Pedro, CA. The chemical storage and transfer facility was contaminated with various solvents due to spillage and a fire. Contamination extended into the salt water table (1.8 meters). Based on the SITE Demonstration and other data, it was concluded that 85% of the volatile organic compounds and 50% of the semivolatile organic compounds were removed from the soil. Fugitive air emissions are very low, and lateral and downward migration of contaminants due to the treatment were minimal. Finally, it was concluded that this in-situ process is cost competitive.

  14. Future research needs associated with the assessment of potential human health risks from exposure to toxic ambient air pollutants.

    PubMed Central

    Möller, L; Schuetzle, D; Autrup, H

    1994-01-01

    This paper presents key conclusions and future research needs from a Workshop on the Risk Assessment of Urban Air, Emissions, Exposure, Risk Identification, and Quantification, which was held in Stockholm during June 1992 by 41 participants from 13 countries. Research is recommended in the areas of identification and quantification of toxics in source emissions and ambient air, atmospheric transport and chemistry, exposure level assessment, the development of improved in vitro bioassays, biomarker development, the development of more accurate epidemiological methodologies, and risk quantification techniques. Studies are described that will be necessary to assess and reduce the level of uncertainties associated with each step of the risk assessment process. International collaborative research efforts between industry and government organizations are recommended as the most effective way to carry out this research. PMID:7529703

  15. Aerosolized ZnO nanoparticles induce toxicity in alveolar type II epithelial cells at the air-liquid interface

    SciTech Connect

    Xie, Yumei; Williams, Nolann G.; Tolic, Ana; Chrisler, William B.; Teeguarden, Justin G.; Maddux, Bettye L.; Pounds, Joel G.; Laskin, Alexander; Orr, Galya

    2012-01-20

    The majority of in vitro studies characterizing the impact of engineered nanoparticles (NPs) on cells that line the respiratory tract were conducted in cells exposed to NPs in suspension. This approach introduces processes that are unlikely to occur during inhaled NP exposures in vivo, such as the shedding of toxic doses of dissolved ions. ZnO NPs are used extensively and pose significant sources for human exposure. Exposures to airborne ZnO NPs can induce adverse effects, but the relevance of the dissolved Zn2+ to the observed effects in vivo is still unclear. Our goal was to mimic in vivo exposures to airborne NPs and decipher the contribution of the intact NP from the contribution of the dissolved ions to airborne ZnO NP toxicity. We established the exposure of alveolar type II epithelial cells to aerosolized NPs at the air-liquid interface (ALI), and compared the impact of aerosolized ZnO NPs and NPs in suspension at the same cellular doses, measured as the number of particles per cell. By evaluating membrane integrity and cell viability 6 and 24 hours post exposure we found that aerosolized NPs induced toxicity at the ALI at doses that were in the same order of magnitude as doses required to induce toxicity in submersed cultures. In addition, distinct patterns of oxidative stress were observed in the two exposure systems. These observations unravel the ability of airborne ZnO NPs to induce toxicity without the contribution of dissolved Zn2+ and suggest distinct mechanisms at the ALI and in submersed cultures.

  16. Three dimensional quantitative structure-toxicity relationship modeling and prediction of acute toxicity for organic contaminants to algae.

    PubMed

    Jin, Xiangqin; Jin, Minghao; Sheng, Lianxi

    2014-08-01

    Although numerous chemicals have been identified to have significant toxicological effect on aquatic organisms, there is still lack of a reliable, high-throughput approach to evaluate, screen and monitor the presence of organic contaminants in aquatic system. In the current study, we proposed a synthetic pipeline to automatically model and predict the acute toxicity of chemicals to algae. In the procedure, a new alignment-free three dimensional (3D) structure characterization method was described and, with this method, several 3D-quantitative structure-toxicity relationship (3D-QSTR) models were developed, from which two were found to exhibit strong internal fitting ability and high external predictive power. The best model was established by Gaussian process (GP), which was further employed to perform extrapolation on a random compound library consisting of 1014 virtually generated substituted benzenes. It was found that (i) substitution number can only exert slight influence on chemical׳s toxicity, but low-substituted benzenes seem to have higher toxicity than those of high-substituted entities, and (ii) benzenes substituted by nitro group and halogens exhibit high acute toxicity as compared to other substituents such as methyl and carboxyl groups. Subsequently, several promising candidates suggested by computational prediction were assayed by using a standard algal growth inhibition test. Consequently, four substituted benzenes, namely 2,3-dinitrophenol, 2-chloro-4-nitroaniline, 1,2,3-trinitrobenzene and 3-bromophenol, were determined to have high acute toxicity to Scenedesmus obliquus, with their EC50 values of 2.5±0.8, 10.5±2.1, 1.4±0.2 and 42.7±5.4μmol/L, respectively.

  17. U. S. Environmental Protection Agency's inhalation RFD methodology: Risk assessment for air toxics

    SciTech Connect

    Jarabek, A.M.; Menache, M.G.; Overton, J.H.; Dourson, M.L.; Miller, F.J.

    1989-01-01

    The U.S. Environmental Protection Agency (U.S. EPA) has advocated the establishment of general and scientific guidelines for the evaluation of toxicological data and their use in deriving benchmark values to protect exposed populations from adverse health effects. The Agency's reference dose (RfD) methodology for deriving benchmark values for noncancer toxicity originally addressed risk assessment of oral exposures. The paper presents a brief background on the development of the inhalation reference dose (RFDi) methodology, including concepts and issues related to addressing the dynamics of the respiratory system as the portal of entry. Different dosimetric adjustments are described that were incorporated into the methodology to account for the nature of the inhaled agent (particle or gas) and the site of the observed toxic effects (respiratory or extrarespiratory). Impacts of these adjustments on the extrapolation of toxicity data of inhaled agents for human health risk assessment and future research directions are also discussed.

  18. 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 ...

  19. VALMET: a valley air pollution model. Final report. Revision 1

    SciTech Connect

    Whiteman, C.D.; Allwine, K.J.

    1985-04-01

    An air quality model is described for predicting air pollution concentrations in deep mountain valleys arising from nocturnal down-valley transport and diffusion of an elevated pollutant plume, and the fumigation of the plume on the valley floor and sidewalls after sunrise. Included is a technical description of the model, a discussion of the model's applications, the required model inputs, sample calculations and model outputs, and a full listing of the FORTRAN computer program. 55 refs., 27 figs., 6 tabs.

  20. Air Quality Modeling Technical Support Document for the 2008 Ozone NAAQS Cross-State Air Pollution Rule Proposal

    EPA Pesticide Factsheets

    In this technical support document (TSD) we describe the air quality modeling performed to support the proposed Cross-State Air Pollution Rule for the 2008 ozone National Ambient Air Quality Standards (NAAQS)

  1. Transgenic mouse models for alcohol metabolism, toxicity, and cancer.

    PubMed

    Heit, Claire; Dong, Hongbin; Chen, Ying; Shah, Yatrik M; Thompson, David C; Vasiliou, Vasilis

    2015-01-01

    Alcohol abuse leads to tissue damage including a variety of cancers; however, the molecular mechanisms by which this damage occurs remain to be fully understood. The primary enzymes involved in ethanol metabolism include alcohol dehydrogenase (ADH), cytochrome P450 isoform 2E1, (CYP2E1), catalase (CAT), and aldehyde dehydrogenases (ALDH). Genetic polymorphisms in human genes encoding these enzymes are associated with increased risks of alcohol-related tissue damage, as well as differences in alcohol consumption and dependence. Oxidative stress resulting from ethanol oxidation is one established pathogenic event in alcohol-induced toxicity. Ethanol metabolism generates free radicals, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS), and has been associated with diminished glutathione (GSH) levels as well as changes in other antioxidant mechanisms. In addition, the formation of protein and DNA adducts associated with the accumulation of ethanol-derived aldehydes can adversely affect critical biological functions and thereby promote cellular and tissue pathology. Animal models have proven to be valuable tools for investigating mechanisms underlying pathogenesis caused by alcohol. In this review, we provide a brief discussion on several animal models with genetic defects in alcohol-metabolizing enzymes and GSH-synthesizing enzymes and their relevance to alcohol research.

  2. Transgenic Mouse Models for Alcohol Metabolism, Toxicity and Cancer

    PubMed Central

    Heit, Claire; Dong, Hongbin; Chen, Ying; Shah, Yatrik M.; Thompson, David C.; Vasiliou, Vasilis

    2015-01-01

    Alcohol abuse leads to tissue damage including a variety of cancers; however, the molecular mechanisms by which this damage occurs remains to be fully understood. The primary enzymes involved in ethanol metabolism include alcohol dehydrogenase (ADH), cytochrome P450 isoform 2E1, (CYP2E1), catalase (CAT), and aldehyde dehydrogenases (ALDH). Genetic polymorphisms in human genes encoding these enzymes are associated with increased risks of alcohol-related tissue damage, as well as differences in alcohol consumption and dependence. Oxidative stress resulting from ethanol oxidation is one established pathogenic event in alcohol-induced toxicity. Ethanol metabolism generates free radicals, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS), and has been associated with diminished glutathione (GSH) levels as well as changes in other antioxidant mechanisms. In addition, the formation of protein and DNA adducts associated with the accumulation of ethanol-derived aldehydes can adversely affect critical biological functions and thereby promote cellular and tissue pathology. Animal models have proven to be valuable tools for investigating mechanisms underlying pathogenesis caused by alcohol. In this review, we provide a brief discussion on several animal models with genetic defects in alcohol metabolizing enzymes and GSH synthesizing enzymes and their relevance to alcohol research. PMID:25427919

  3. A PROBABILISTIC MODELING FRAMEWORK FOR PREDICTING POPULATION EXPOSURES TO BENZENE

    EPA Science Inventory

    The US Environmental Protection Agency (EPA) is modifying their probabilistic Stochastic Human Exposure Dose Simulation (SHEDS) model to assess aggregate exposures to air toxics. Air toxics include urban Hazardous Air Pollutants (HAPS) such as benzene from mobile sources, part...

  4. Fact Sheets: Final Rules to Reduce Toxic Air Pollutants from Surface Coating of Metal Cans

    EPA Pesticide Factsheets

    This page contains the August 2003 final rule fact sheet and the December 2005 final rule fact sheet that contain information on the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Surface Coating of Metal Cans.

  5. AIR PARTICULATE POLLUTION CARDIOVASCULAR TOXICITY: HAZARD IDENTIFICATION AND MECHANISMS OF ACTION

    EPA Science Inventory


    The overall weight of evidence from epidemiological studies has shown statistical associations between air particulate pollution exposure and mortality\\morbidity particularly within individuals with cardiovascular disease (1-4). Identification of causal particle properties ...

  6. Fact Sheets: Air Toxics Rules for the Manufacture of Amino/Phenolic Resins

    EPA Pesticide Factsheets

    This page contains a December 1999 fact sheet for the proposed National Emission Standards for Hazardous Air Pollutants (NESHAP): Manufacture of Amino/Phenolic Resins and a September 2014 fact sheet with information regarding the final NESHAP

  7. Fact Sheets: Air Toxics Standards for Area Sources in Seven Industry Sectors

    EPA Pesticide Factsheets

    This page contains a June 2007 fact sheet and a March 2008 fact sheet for the National Emission Standards for Hazardous Air Pollutants (NESHAP): Wood Preserving Area Sources. These documents provide a summary of the information for this NESHAP.

  8. Air toxics and epigenetic effects: ozone altered microRNAs in the sputum of human subjects

    EPA Science Inventory

    Ozone (03) is a criteria air pollutant that is associated with numerous adverse health effects, including altered respiratory immune responses. Despite its deleterious health effects, possible epigenetic mechanisms underlying 03-induced health effects remain understudied. MicroRN...

  9. Final Rule to Reduce Toxic Air Emissions from Lime Manufacturing Plants Fact Sheet

    EPA Pesticide Factsheets

    This page contains an August 2003 fact sheet with information regarding the National Emissions Standards for Hazardous Air Pollutants (NESHAP) for Lime Manufacturing Plants. This document provides a summary of the information for this NESHAP.

  10. THE ATMOSPHERIC MODEL EVALUATION TOOL (AMET); AIR QUALITY MODULE

    EPA Science Inventory

    This presentation reviews the development of the Atmospheric Model Evaluation Tool (AMET) air quality module. The AMET tool is being developed to aid in the model evaluation. This presentation focuses on the air quality evaluation portion of AMET. Presented are examples of the...

  11. ENVIRONMENTAL CONTROL OF TOXIC METAL AIR EMISSIONS FROM THE COMBUSTION OF COAL AND WASTES

    EPA Science Inventory

    The paper is concerned with the partitioning of toxic metals (e.g., arsenic, selenium, mercury, chromium, lead, and cadmium) during combustion, and with the mitigation of their effect on the environment using high-temperature sorbents. The paper is divided into three parts: (1) t...

  12. Toxic Acid Gas Absorber Design Considerations for Air Pollution Control in Process Industries

    ERIC Educational Resources Information Center

    Manyele, S. V.

    2008-01-01

    This paper analyses the design parameters for an absorber used for removal of toxic acid gas (in particular sulfur dioxide) from a process gas stream for environmental health protection purposes. Starting from the equilibrium data, Henry's law constant was determined from the slope of the y-x diagram. Based on mass balances across the absorber,…

  13. DEVELOPMENT AND ANALYSIS OF AIR QUALITY MODELING SIMULATIONS FOR HAZARDOUS AIR POLLUTANTS

    EPA Science Inventory

    The concentrations of five hazardous air pollutants were simulated using the Community Multi Scale Air Quality (CMAQ) modeling system. Annual simulations were performed over the continental United States for the entire year of 2001 to support human exposure estimates. Results a...

  14. A review of air exchange rate models for air pollution exposure assessments.

    PubMed

    Breen, Michael S; Schultz, Bradley D; Sohn, Michael D; Long, Thomas; Langstaff, John; Williams, Ronald; Isaacs, Kristin; Meng, Qing Yu; Stallings, Casson; Smith, Luther

    2014-11-01

    A critical aspect of air pollution exposure assessments is estimation of the air exchange rate (AER) for various buildings where people spend their time. The AER, which is the rate of exchange of indoor air with outdoor air, is an important determinant for entry of outdoor air pollutants and for removal of indoor-emitted air pollutants. This paper presents an overview and critical analysis of the scientific literature on empirical and physically based AER models for residential and commercial buildings; the models highlighted here are feasible for exposure assessments as extensive inputs are not required. Models are included for the three types of airflows that can occur across building envelopes: leakage, natural ventilation, and mechanical ventilation. Guidance is provided to select the preferable AER model based on available data, desired temporal resolution, types of airflows, and types of buildings included in the exposure assessment. For exposure assessments with some limited building leakage or AER measurements, strategies are described to reduce AER model uncertainty. This review will facilitate the selection of AER models in support of air pollution exposure assessments.

  15. Analysis of Aircraft Evasion Strategies in Air-to-Air Missille Effectiveness Models

    DTIC Science & Technology

    1975-08-01

    AD-A015 238 ANALYSIS OF AIRCRAFT EVASION STRATEGIES IN AIR-TO-AIR MISSILE EFFECTIVENESS MObri ’ G. Carpenter, et al Grumman Aerospace Corporation ...overall tep t Es CIS*atiet d) Oft ’IsNA 1tTNG AC ?v I TV ? corpor te author) 2S. REPORT SECUNITY CLASSIrICA TION Unclassified ;rummn Aerospace... Corporation b RoU N/A I NEPOA’ I ?LE nalysis of Aircraft Evasion Strategies in Air-to-Air Missile Effectiveness Models 4 DESCRIP T IVE *40TS ’Type of repct

  16. Toxic volatile organic compounds in environmental tobacco smoke: Emission factors for modeling exposures of California populations

    SciTech Connect

    Daisey, J.M.; Mahanama, K.R.R.; Hodgson, A.T.

    1994-10-01

    The primary objective of this study was to measure emission factors for selected toxic air contaminants in environmental tobacco smoke (ETS) using a room-sized environmental chamber. The emissions of 23 volatile organic compounds (VOCs), including, 1,3-butadiene, three aldehydes and two vapor-phase N-nitrosamines were determined for six commercial brands of cigarettes and reference cigarette 1R4F. The commercial brands were selected to represent 62.5% of the cigarettes smoked in California. For each brand, three cigarettes were machine smoked in the chamber. The experiments were conducted over four hours to investigate the effects of aging. Emission factors of the target compounds were also determined for sidestream smoke (SS). For almost all target compounds, the ETS emission factors were significantly higher than the corresponding SS values probably due to less favorable combustion conditions and wall losses in the SS apparatus. Where valid comparisons could be made, the ETS emission factors were generally in good agreement with the literature. Therefore, the ETS emission factors, rather than the SS values, are recommended for use in models to estimate population exposures from this source. The variabilities in the emission factors ({mu}g/cigarette) of the selected toxic air contaminants among brands, expressed as coefficients of variation, were 16 to 29%. Therefore, emissions among brands were Generally similar. Differences among brands were related to the smoked lengths of the cigarettes and the masses of consumed tobacco. Mentholation and whether a cigarette was classified as light or regular did not significantly affect emissions. Aging was determined not to be a significant factor for the target compounds. There were, however, deposition losses of the less volatile compounds to chamber surfaces.

  17. INTERCOMPARISON OF ALTERNATIVE VEGETATION DATABASES FOR REGIONAL AIR QUALITY MODELING

    EPA Science Inventory

    Vegetation cover data are used to characterize several regional air quality modeling processes, including the calculation of heat, moisture, and momentum fluxes with the Mesoscale Meteorological Model (MM5) and the estimate of biogenic volatile organic compound and nitric oxide...

  18. Bayesian Analysis of a Reduced-Form Air Quality Model

    EPA Science Inventory

    Numerical air quality models are being used for assessing emission control strategies for improving ambient pollution levels across the globe. This paper applies probabilistic modeling to evaluate the effectiveness of emission reduction scenarios aimed at lowering ground-level oz...

  19. Human intake fraction of toxic pollutants: a model comparison between caltox and uses-lca

    SciTech Connect

    Huijbregts, Mark A.J.; Geelen, Loes M.J.; Hertwich, Edgar G.; McKone, Thomas E.; van de Meent, Dik

    2004-01-06

    In Life Cycle Assessment and Comparative Risk Assessment potential human exposure to toxic pollutants can be expressed as the human intake fraction (iF), representing the fraction of the quantity emitted that enters the human population. To assess model uncertainty in the human intake fraction, ingestion and inhalation iFs of 367 substances emitted to air and freshwater were calculated with two commonly applied multi-media fate and exposure models, CalTOX and USES-LCA. Comparison of the model outcomes reveal that uncertainty in the ingestion iFs was up to a factor of 70. The uncertainty in the inhalation iFs was up to a factor of 865,000. The comparison showed that relatively few model differences account for the uncertainties found. An optimal model structure in the calculation of human intake fractions can be achieved by including (1) rain and no-rain scenarios, (2) a continental sea water compartment, (3) drinking water purification, (4) pH-correction of chemical properties, and (5) aerosol-associated deposition on plants. Finally, vertical stratification of the soil compartment combined with a chemical-dependent soil depth may be considered in future intake fraction calculations.

  20. Air toxics exposure from vehicle emissions at a U.S. border crossing: Buffalo Peace Bridge Study.

    PubMed

    Spengler, John; Lwebuga-Mukasa, Jamson; Vallarino, Jose; Melly, Steve; Chillrud, Steve; Baker, Joel; Minegishi, Taeko

    2011-07-01

    The Peace Bridge in Buffalo, New York, which spans the Niagara River at the east end of Lake Erie, is one of the busiest U.S. border crossings. The Peace Bridge plaza on the U.S. side is a complex of roads, customs inspection areas, passport control areas, and duty-free shops. On average 5000 heavy-duty diesel trucks and 20,000 passenger cars traverse the border daily, making the plaza area a potential "hot spot" for emissions from mobile sources. In a series of winter and summer field campaigns, we measured air pollutants, including many compounds considered by the U.S. Environmental Protection Agency (EPA*) as mobile-source air toxics (MSATs), at three fixed sampling sites: on the shore of Lake Erie, approximately 500 m upwind (under predominant wind conditions) of the Peace Bridge plaza; immediately downwind of (adjacent to) the plaza; and 500 m farther downwind, into the community of west Buffalo. Pollutants sampled were particulate matter (PM) < or = 10 microm (PM10) and < or = 2.5 microm (PM2.5) in aerodynamic diameter, elemental carbon (EC), 28 elements, 25 volatile organic compounds (VOCs) including 3 carbonyls, 52 polycyclic aromatic hydrocarbons (PAHs), and 29 nitrogenated polycyclic aromatic hydrocarbons (NPAHs). Spatial patterns of counts of ultrafine particles (UFPs, particles < 0.1 microm in aerodynamic diameter) and of particle-bound PAH (pPAH) concentrations were assessed by mobile monitoring in the neighborhood adjacent to the Peace Bridge plaza using portable instruments and Global Positioning System (GPS) tracking. The study was designed to assess differences in upwind and downwind concentrations of MSATs, in areas near the Peace Bridge plaza on the U.S. side of the border. The Buffalo Peace Bridge Study featured good access to monitoring locations proximate to the plaza and in the community, which are downwind with the dominant winds from the direction of Lake Erie and southern Ontario. Samples from the lakeside Great Lakes Center (GLC), which

  1. Air Pollution Modeling Using A 3-d Hemispheric Nested Model

    NASA Astrophysics Data System (ADS)

    Frohn, L. M.; Christensen, J. H.; Brandt, J.; Hertel, O.

    A 3-D Eulerian transport-chemistry model based on modules and parameterisations from models developed over the last decade at the National Environmental Research Institute (DREAM, DEHM, ACDEP and DEOM) has been developed. The model is hemispheric with currently two nests implemented. The horizontal resolution in the mother domain is 150 km x 150 km. First nest covers the European area wit,h a 50 km x 50 km resolution, second covers the Scandinavian area with a resolution of 16.67 km x 16.67 km. The model employs a chemical scheme (originally 53 species) which has been modified to include a detailed description of the nitrogen chemistry. The concentration of air pollutants, such as sulfur and nitrogen in various forms, has been calculated with the model, applying no nesting as well as one and two nests. The calculated values have been validated by comparison to measurements from more than 200 EMEP monitoring stations. Furthermore deposition of nitrogen to marine waters has been estimated with the model. The goal is to obtain an improved description of spatial and temporal variations in the nutrient deposition to the marine environment. In the presentation the physics and chemistry of the model will be shortly described. Validations of the model calculations by comparison to EMEP measurements will be shown and discussed together with the results of the deposition calculations.

  2. Toxicity to Daphnia magna and Vibrio fischeri of Kraft bleach plant effluents treated by catalytic wet-air oxidation.

    PubMed

    Pintar, Albin; Besson, Michèle; Gallezot, Pierre; Gibert, Janine; Martin, Dominique

    2004-01-01

    Two Kraft-pulp bleaching effluents from a sequence of treatments which include chlorine dioxide and caustic soda were treated by catalytic wet-air oxidation (CWAO) at T=463 K in trickle-bed and batch-recycle reactors packed with either TiO2 extrudates or Ru(3 wt%)/TiO2 catalyst. Chemical analyses (TOC removal, color, HPLC) and bioassays (48-h and 30-min acute toxicity tests using Daphnia magna and Vibrio fischeri, respectively) were used to get information about the toxicity impact of the starting effluents and of the treated solutions. Under the operating conditions, complex organic compounds are mostly oxidized into carbon dioxide and water, along with short-chain carboxylic acids. Bioassays were found as a complement to chemical analyses for ensuring the toxicological impact on the ecosystem. In spite of a large decrease of TOC, the solutions of end products were all more toxic to Daphnia magna than the starting effluents by factors ranging from 2 to 33. This observation is attributed to the synergistic effects of acetic acid and salts present in the solutions. On the other hand, toxicity reduction with respect to Vibrio fischeri was achieved: detoxification factors greater than unity were measured for end-product solutions treated in the presence of the Ru(3 wt%)/TiO2 catalyst, suggesting the absence of cumulative effect for this bacteria, or a lower sensitivity to the organic acids and salts. Bleach plant effluents treated by the CWAO process over the Ru/TiO2 catalyst were completely biodegradable.

  3. Evaluating CMIP5 models using AIRS tropospheric air temperature and specific humidity climatology

    NASA Astrophysics Data System (ADS)

    Tian, Baijun; Fetzer, Eric J.; Kahn, Brian H.; Teixeira, Joao; Manning, Evan; Hearty, Thomas

    2013-01-01

    This paper documents the climatological mean features of the Atmospheric Infrared Sounder (AIRS) monthly mean tropospheric air temperature (ta, K) and specific humidity (hus, kg/kg) products as part of the Obs4MIPs project and compares them to those from NASA's Modern Era Retrospective analysis for Research and Applications (MERRA) for validation and 16 models from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) for CMIP5 model evaluation. MERRA is warmer than AIRS in the free troposphere but colder in the boundary layer with differences typically less than 1 K. MERRA is also drier (~10%) than AIRS in the tropical boundary layer but wetter (~30%) in the tropical free troposphere and the extratropical troposphere. In particular, the large MERRA-AIRS specific humidity differences are mainly located in the deep convective cloudy regions indicating that the low sampling of AIRS in the cloudy regions may be the main reason for these differences. In comparison to AIRS and MERRA, the sixteen CMIP5 models can generally reproduce the climatological features of tropospheric air temperature and specific humidity well, but several noticeable biases exist. The models have a tropospheric cold bias (around 2 K), especially in the extratropical upper troposphere, and a double-ITCZ problem in the troposphere from 1000 hPa to 300 hPa, especially in the tropical Pacific. The upper-tropospheric cold bias exists in the most (13 of 16) models, and the double-ITCZ bias is found in all 16 CMIP5 models. Both biases are independent of the reference dataset used (AIRS or MERRA).

  4. 40 CFR Table 4 to Subpart Dddd of... - Model Rule-Toxic Equivalency Factors

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 7 2013-07-01 2013-07-01 false Model Rule-Toxic Equivalency Factors 4... Compliance Times for Commercial and Industrial Solid Waste Incineration Units Pt. 60, Subpt. DDDD, Table 4 Table 4 to Subpart DDDD of Part 60—Model Rule—Toxic Equivalency Factors Dioxin/furan isomer...

  5. 40 CFR Table 4 to Subpart Dddd of... - Model Rule-Toxic Equivalency Factors

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 7 2012-07-01 2012-07-01 false Model Rule-Toxic Equivalency Factors 4... Compliance Times for Commercial and Industrial Solid Waste Incineration Units Pt. 60, Subpt. DDDD, Table 4 Table 4 to Subpart DDDD of Part 60—Model Rule—Toxic Equivalency Factors Dioxin/furan congener...

  6. Modelling and Assessing Air-Surface Integration

    DTIC Science & Technology

    2011-06-01

    2011), Qu?c City , Qu?c, Canada, June 21-23, 2011. U.S. Government or Federal Rights License. 14. ABSTRACT Air-Surface Integration (ASI) is an...structure capability and identifies socio-technical issues in the ASI system for capability designers . 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF...for capability designers . 1. Introduction Air Surface Integration (ASI) has been conducted by forces in a variety of operations dating back to

  7. Wastewater/Storm Water Characterization and Toxicity Identification Evaluation, Sheppard Air Force Base, Texas

    DTIC Science & Technology

    1991-12-01

    REPORTING CERIODAPHNIA DUBIA SURVIVAL AND REPRODUCTION TEST Permittee: Sheppard Air Force Base NPDES No.: TX0025429 Composite collected FROM: am/pm...Continued) BIOMONITORING REPORTING CERIODAPHNIA DUBIA SURVIVAL AND REPRODUCTION TEST Permittee: Sheppard Air Force Base NPDES No.: TX0025429 PERCENT... Ceriodaphnia dubia Date Result (Pass/Fail) Result (Pass/Fa Sep 91 P P Aug 91 P P Jul 91 P F Jun 91 P P May 91 P P Apr 91 P P Mar 91 P P Feb 91 P F

  8. Modeling, Monitoring and Fault Diagnosis of Spacecraft Air Contaminants

    NASA Technical Reports Server (NTRS)

    Ramirez, W. Fred; Skliar, Mikhail; Narayan, Anand; Morgenthaler, George W.; Smith, Gerald J.

    1996-01-01

    Progress and results in the development of an integrated air quality modeling, monitoring, fault detection, and isolation system are presented. The focus was on development of distributed models of the air contaminants transport, the study of air quality monitoring techniques based on the model of transport process and on-line contaminant concentration measurements, and sensor placement. Different approaches to the modeling of spacecraft air contamination are discussed, and a three-dimensional distributed parameter air contaminant dispersion model applicable to both laminar and turbulent transport is proposed. A two-dimensional approximation of a full scale transport model is also proposed based on the spatial averaging of the three dimensional model over the least important space coordinate. A computer implementation of the transport model is considered and a detailed development of two- and three-dimensional models illustrated by contaminant transport simulation results is presented. The use of a well established Kalman filtering approach is suggested as a method for generating on-line contaminant concentration estimates based on both real time measurements and the model of contaminant transport process. It is shown that high computational requirements of the traditional Kalman filter can render difficult its real-time implementation for high-dimensional transport model and a novel implicit Kalman filtering algorithm is proposed which is shown to lead to an order of magnitude faster computer implementation in the case of air quality monitoring.

  9. Eight Year Climatologies from Observational (AIRS) and Model (MERRA) Data

    NASA Technical Reports Server (NTRS)

    Hearty, Thomas; Savtchenko, Andrey; Won, Young-In; Theobalk, Mike; Vollmer, Bruce; Manning, Evan; Smith, Peter; Ostrenga, Dana; Leptoukh, Greg

    2010-01-01

    We examine climatologies derived from eight years of temperature, water vapor, cloud, and trace gas observations made by the Atmospheric Infrared Sounder (AIRS) instrument flying on the Aqua satellite and compare them to similar climatologies constructed with data from a global assimilation model, the Modern Era Retrospective-Analysis for Research and Applications (MERRA). We use the AIRS climatologies to examine anomalies and trends in the AIRS data record. Since sampling can be an issue for infrared satellites in low earth orbit, we also use the MERRA data to examine the AIRS sampling biases. By sampling the MERRA data at the AIRS space-time locations both with and without the AIRS quality control we estimate the sampling bias of the AIRS climatology and the atmospheric conditions where AIRS has a lower sampling rate. While the AIRS temperature and water vapor sampling biases are small at low latitudes, they can be more than a few degrees in temperature or 10 percent in water vapor at higher latitudes. The largest sampling biases are over desert. The AIRS and MERRA data are available from the Goddard Earth Sciences Data and Information Services Center (GES DISC). The AIRS climatologies we used are available for analysis with the GIOVANNI data exploration tool. (see, http://disc.gsfc.nasa.gov).

  10. A framework and plan for modeling and managing toxic chemicals in Lake Michigan

    SciTech Connect

    Richardson, W.; Endicott, D.

    1995-12-31

    Although there have been substantial reductions in loadings and subsequent concentrations of many anthropogenic chemicals in the water, sediment, and ecosystem of Lake Michigan, levels for many remain above established standards or objectives. Also, ecological impacts remain probable as, for example, Lake Michigan lake trout do not reproduce naturally. A preliminary assessment of chemical sources and fate has been completed using a screening model. For PCBs this assessment indicates levels in lake trout will remain above 1 mg/kg even if all point or watershed sources could be eliminated. This is because of estimated atmospheric interaction and exchange. Because of the major ecological and economical consequences, the screening results need to be scientifically validated. This is being done by the Great Lakes National Program Office (GLNPO) in cooperation with the Office of Research and Development (ORD) and other state and academic organizations. A workplan has been prepared for developing and testing a series of more spatially resolved models for PCBs, atrazine, mercury, and trans-nonachlor. In addition, plans include the direct coupling of air and water transport and fate models. A summary of this workplan and preliminary modeling results will be presented and related to the issues of managing toxic substances in Lake Michigan and the Great Lakes.

  11. A Biological Model of the Effects of Toxic Substances

    DTIC Science & Technology

    1991-11-29

    testing the system’s response to different classes of toxic chemicals. 14. SUBJECT TIRMS IS. NUMBER Of PAGES Bioassay, Environmental toxins , Detoxification...Painful. Irritant and Toxic Stimuli. Neurons were found to be reactive to bradykinin (Fig. 12), capsaicin (Fig. 13: a classical pain-producing substance...the same concentration of bradykinin. 41 49..9 -40.0 40. 9.9 ... ............... ......... -2.3 FIGURE 13. Stimulation with capsaicin . Stimulation is

  12. Centrifuge modeling of air sparging - a study of air flow through saturated porous media.

    PubMed

    Marulanda, C; Culligan, P J; Germaine, J T

    2000-02-25

    The success of air sparging as a remedial technology for treatment of contaminated aquifers is well documented. However, there is no consensus, to date, on the mechanisms that control the flow of injected air through the saturated ground. Currently, only qualitative results from laboratory experiments are available to predict the zone of influence of a sparging well. Given that the patterns of air flow through the soil will ultimately determine the efficiency of an air sparging treatment, it is important to quantify how sparged air travels through a saturated porous medium. The main objective of this research is to develop a model that describes air transport through saturated porous media. This paper presents results from an ongoing study that employs centrifuge modeling to reproduce in situ air sparging conditions. Centrifuge testing is an experimental technique that allows reduced-scale duplication, in the laboratory, of the stresses and pressure distributions encountered in the field. In situ conditions are critical in the development of actual air flow patterns. Experiments are being conducted in a transparent porous medium consisting of crushed borosilicate glass submerged in fluids of matching indices of refraction. Air is observed as it flows through the porous medium at varying gravitational accelerations. Recorded images of experiments allow the determination of flow patterns, breakthrough velocities, and plume shapes as a function of g-level and injection pressure. Results show that air flow patterns vary from fingering, at low g-levels, to pulsing at higher accelerations. Grain and pore size distribution of the porous medium do not exclusively control air flow characteristics. Injector geometry has a definite effect on breakthrough velocities and air plume shapes. Experiments have been conducted to compare the velocity of air flow through the saturated porous medium to that of air in pure liquids. Results show that the velocity of air through the medium

  13. MOAtox: A comprehensive mode of action and acute aquatic toxicity database for predictive model development.

    PubMed

    Barron, M G; Lilavois, C R; Martin, T M

    2015-04-01

    The mode of toxic action (MOA) has been recognized as a key determinant of chemical toxicity and as an alternative to chemical class-based predictive toxicity modeling. However, the development of quantitative structure activity relationship (QSAR) and other models has been limited by the availability of comprehensive high quality MOA and toxicity databases. The current study developed a dataset of MOA assignments for 1213 chemicals that included a diversity of metals, pesticides, and other organic compounds that encompassed six broad and 31 specific MOAs. MOA assignments were made using a combination of high confidence approaches that included international consensus classifications, QSAR predictions, and weight of evidence professional judgment based on an assessment of structure and literature information. A toxicity database of 674 acute values linked to chemical MOA was developed for fish and invertebrates. Additionally, species-specific measured or high confidence estimated acute values were developed for the four aquatic species with the most reported toxicity values: rainbow trout (Oncorhynchus mykiss), fathead minnow (Pimephales promelas), bluegill (Lepomis macrochirus), and the cladoceran (Daphnia magna). Measured acute toxicity values met strict standardization and quality assurance requirements. Toxicity values for chemicals with missing species-specific data were estimated using established interspecies correlation models and procedures (Web-ICE; http://epa.gov/ceampubl/fchain/webice/), with the highest confidence values selected. The resulting dataset of MOA assignments and paired toxicity values are provided in spreadsheet format as a comprehensive standardized dataset available for predictive aquatic toxicology model development.

  14. CO-DEPENDENCIES OF REACTIVE AIR TOXIC AND CRITERIA POLLUTANTS ON EMISSION REDUCTIONS

    EPA Science Inventory

    It is important to understand the effect of emission controls on the concentrations of ozone, PM2.5, and hazardous air pollutants simultaneously, in order to evaluate the full range of both health related and economic effects. Until recently, the capability of simultan...

  15. CHARACTERIZATION OF AIR TOXICS FROM AN OIL-FIRED FIRETUBE BOILER

    EPA Science Inventory

    Tests were conducted on a commercially available firetube package boiler running on #2 through #6 oils to determine the emissions levels of hazardous air pollutants (HAPs) from the combustion of four fuel oils. Flue gas was sampled to determine levels of volatile and semivolatile...

  16. DETECTION AND IDENTIFICATION OF TOXIC AIR POLLUTANTS USING AIRBORNE LWIR HYPERSPECTRAL IMAGING

    EPA Science Inventory

    Gaseous releases from petrochemical, refinery, and electrical production facilities can contribute to regional air quality problems. Fugitive emissions or leaks can be costly to industry in terms of lost materials and products. Ground-based sampling and monitoring for leaks are t...

  17. EPA DETERMINATION STUDIES ON THE CONTROL OF TOXIC AIR POLLUTION EMISSIONS FROM ELECTRIC UTILITY BOILERS

    EPA Science Inventory

    The U. S. Environmental Protection Agency (EPA) is to determine whether the regulation of hazardous air pollution (HAP) emissions from electric utility generating plants is necessary. This determination is to be made on or before December 15, 2000. It focuses primarily on the nee...

  18. Enhanced, multi criteria based site selection to measure mobile source toxic air pollutants

    EPA Science Inventory

    Research studies being conducted by the U.S. Environmental Protection Agency in collaboration with the U.S. Federal Highway Administration are designed to establish relationships between concentrations of highway vehicle air pollutants and variations in these concentrations as a ...

  19. DEMONSTRATION BULLETIN: IN-SITU STEAM/HOT AIR SOIL STRIPPING TOXIC TREATMENT (USA) INC.

    EPA Science Inventory

    This technology uses steam and hot air to strip volatile organics from contaminated soil. The treatment equipment is mobile and treats the soil in-situ without need for soil excavation or transportation. The organic contaminants volatilized from the soil are condensed and col...

  20. Urban Air Quality Modelling with AURORA: Prague and Bratislava

    NASA Astrophysics Data System (ADS)

    Veldeman, N.; Viaene, P.; De Ridder, K.; Peelaerts, W.; Lauwaet, D.; Muhammad, N.; Blyth, L.

    2012-04-01

    The European Commission, in its strategy to protect the health of the European citizens, states that in order to assess the impact of air pollution on public health, information on long-term exposure to air pollution should be available. Currently, indicators of air quality are often being generated using measured pollutant concentrations. While air quality monitoring stations data provide accurate time series information at specific locations, air quality models have the advantage of being able to assess the spatial variability of air quality (for different resolutions) and predict air quality in the future based on different scenarios. When running such air quality models at a high spatial and temporal resolution, one can simulate the actual situation as closely as possible, allowing for a detailed assessment of the risk of exposure to citizens from different pollutants. AURORA (Air quality modelling in Urban Regions using an Optimal Resolution Approach), a prognostic 3-dimensional Eulerian chemistry-transport model, is designed to simulate urban- to regional-scale atmospheric pollutant concentration and exposure fields. The AURORA model also allows to calculate the impact of changes in land use (e.g. planting of trees) or of emission reduction scenario's on air quality. AURORA is currently being applied within the ESA atmospheric GMES service, PASODOBLE (http://www.myair-eu.org), that delivers information on air quality, greenhouse gases, stratospheric ozone, … At present there are two operational AURORA services within PASODOBLE. Within the "Air quality forecast service" VITO delivers daily air quality forecasts for Belgium at a resolution of 5 km and for the major Belgian cities: Brussels, Ghent, Antwerp, Liege and Charleroi. Furthermore forecast services are provided for Prague, Czech Republic and Bratislava, Slovakia, both at a resolution of 1 km. The "Urban/regional air quality assessment service" provides urban- and regional-scale maps (hourly resolution

  1. Quantitative Structure--Activity Relationship Modeling of Rat Acute Toxicity by Oral Exposure

    EPA Science Inventory

    Background: Few Quantitative Structure-Activity Relationship (QSAR) studies have successfully modeled large, diverse rodent toxicity endpoints. Objective: In this study, a combinatorial QSAR approach has been employed for the creation of robust and predictive models of acute toxi...

  2. Rodent models of cardiopulmonary disease: their potential applicability in studies of air pollutant susceptibility.

    PubMed Central

    Kodavanti, U P; Costa, D L; Bromberg, P A

    1998-01-01

    The mechanisms by which increased mortality and morbidity occur in individuals with preexistent cardiopulmonary disease following acute episodes of air pollution are unknown. Studies involving air pollution effects on animal models of human cardiopulmonary diseases are both infrequent and difficult to interpret. Such models are, however, extensively used in studies of disease pathogenesis. Primarily they comprise those developed by genetic, pharmacologic, or surgical manipulations of the cardiopulmonary system. This review attempts a comprehensive description of rodent cardiopulmonary disease models in the context of their potential application to susceptibility studies of air pollutants regardless of whether the models have been previously used for such studies. The pulmonary disease models include bronchitis, emphysema, asthma/allergy, chronic obstructive pulmonary disease, interstitial fibrosis, and infection. The models of systemic hypertension and congestive heart failure include: those derived by genetics (spontaneously hypertensive, Dahl S. renin transgenic, and other rodent models); congestive heart failure models derived by surgical manipulations; viral myocarditis; and cardiomyopathy induced by adriamycin. The characteristic pathogenic features critical to understanding the susceptibility to inhaled toxicants are described. It is anticipated that this review will provide a ready reference for the selection of appropriate rodent models of cardiopulmonary diseases and identify not only their pathobiologic similarities and/or differences to humans but also their potential usefulness in susceptibility studies. Images Figure 2 PMID:9539009

  3. Heme Oxygenase-1 Protects Endothelial Cells from the Toxicity of Air Pollutant Chemicals

    PubMed Central

    Dittmar, Michael; Lulla, Aaron; Araujo, Jesus A.

    2015-01-01

    Diesel exhaust particles (DEP) are a major component of diesel emissions, responsible for a large portion of their toxicity. In this study, we examined the toxic effects of DEP on endothelial cells and the role of DEP-induced heme oxygenase-1 (HO-1) expression. Human microvascular endothelial cells (HMEC) were treated with an organic extract of DEP from an automobile engine (A-DEP) or a forklift engine (F-DEP) for 1 and 4 hours. ROS generation, cell viability, lactate dehydrogenase leakage, expression of HO-1, inflammatory genes, cell adhesion molecules and UPR gene were assessed. HO-1 expression and/or activity were inhibited by siRNA or Tin protoporphyrin (Sn PPIX) and enhanced by an expression plasmid or Cobalt protoporphyrin (CoPPIX). Exposure to 25 μg/ml of A-DEP and F-DEP significantly induced ROS production, cellular toxicity and greater levels of inflammatory and cellular adhesion molecules but in a different degree. Inhibition of HO-1 enzymatic activity with SnPPIX and silencing of the HO-1 gene by siRNA enhanced DEP-induced ROS production, further decreased cell viability and increased expression of inflammatory and cell adhesion molecules. On the other hand, overexpression of the HO-1 gene by a pcDNA 3.1D/V5-HO-1 plasmid significantly mitigated ROS production, increased cell survival and decreased the expression of inflammatory genes. HO-1 expression protected HMEC from DEP-induced prooxidative and proinflammatory effects. Modulation of HO-1 expression could potentially serve as a therapeutic target in an attempt to inhibit the cardiovascular effects of ambient PM. PMID:25620054

  4. Heme oxygenase-1 protects endothelial cells from the toxicity of air pollutant chemicals.

    PubMed

    Lawal, Akeem O; Zhang, Min; Dittmar, Michael; Lulla, Aaron; Araujo, Jesus A

    2015-05-01

    Diesel exhaust particles (DEPs) are a major component of diesel emissions, responsible for a large portion of their toxicity. In this study, we examined the toxic effects of DEPs on endothelial cells and the role of DEP-induced heme oxygenase-1 (HO-1) expression. Human microvascular endothelial cells (HMECs) were treated with an organic extract of DEPs from an automobile engine (A-DEP) or a forklift engine (F-DEP) for 1 and 4h. ROS generation, cell viability, lactate dehydrogenase leakage, expression of HO-1, inflammatory genes, cell adhesion molecules and unfolded protein respone (UPR) gene were assessed. HO-1 expression and/or activity were inhibited by siRNA or tin protoporphyrin (Sn PPIX) and enhanced by an expression plasmid or cobalt protoporphyrin (CoPPIX). Exposure to 25μg/ml of A-DEP and F-DEP significantly induced ROS production, cellular toxicity and greater levels of inflammatory and cellular adhesion molecules but to a different degree. Inhibition of HO-1 enzymatic activity with SnPPIX and silencing of the HO-1 gene by siRNA enhanced DEP-induced ROS production, further decreased cell viability and increased expression of inflammatory and cell adhesion molecules. On the other hand, overexpression of the HO-1 gene by a pcDNA 3.1D/V5-HO-1 plasmid significantly mitigated ROS production, increased cell survival and decreased the expression of inflammatory genes. HO-1 expression protected HMECs from DEP-induced prooxidative and proinflammatory effects. Modulation of HO-1 expression could potentially serve as a therapeutic target in an attempt to inhibit the cardiovascular effects of ambient PM.

  5. ROLE OF MODELS IN AIR QUALITY MANAGEMENT DECISIONS

    EPA Science Inventory

    Within the frame of the US-India bilateral agreement on environmental cooperation, a team of US scientists have been helping India in designing emission control policies to address urban air quality problems. This presentation discusses how air quality models need to be used for ...

  6. Recent Advances in WRF Modeling for Air Quality Applications

    EPA Science Inventory

    The USEPA uses WRF in conjunction with the Community Multiscale Air Quality (CMAQ) for air quality regulation and research. Over the years we have added physics options and geophysical datasets to the WRF system to enhance model capabilities especially for extended retrospective...

  7. How Good and Useful Are Air Pollution Models?

    ERIC Educational Resources Information Center

    Environmental Science and Technology, 1973

    1973-01-01

    The Regional Air Pollution Study (RAPS) to be conducted in St. Louis, is the largest air monitoring program of the Environmental Protection Agency. A key segment will be the collection of a data base on which this system of mathematical models can be tested and upon which submodels can be validated. (BL)

  8. A model to predict threshold concentrations for toxic effects of chlorinated benzenes in sediment

    SciTech Connect

    Fuchsman, P.C.; Duda, D.J.; Barber, T.R.

    1999-09-01

    A probabilistic model was developed to predict effects threshold concentrations for chlorinated benzenes in sediment. Based on published quantitative structure-activity relationships relating the toxicity of chlorinated benzenes to the degree of chlorination, congeners with the same number of chlorine substitutions were considered toxicologically equivalent. Hexachlorobenzene was excluded from the assessment based on a lack of aquatic toxicity at the water solubility limit. The equilibrium partitioning approach was applied in a probabilistic analysis to derive predicted effects thresholds (PETs) for each chlorinated benzene group, with model input distributions defined by published log K{sub ow} values and aquatic toxicity data extracted from the published literature. The probabilistic distributions of PETs generally increased with chlorination, with 20th percentile values ranging from 3.2 mg/kg{sub 1{degree}OC} for chlorobenzene to 67 mg/kg{sub 1%OC} for tetrachlorobenzene congeners. The toxicity of total chlorinated benzenes in sediment can be assessed by applying the PETs in a toxic index model, based on the assumption that multiple chlorinated benzene congeners will show approximately additive toxicity, as characteristic of nonpolar narcotic toxicants. The 20th percentile PET values are one to two orders of magnitude higher than published screening-level guidelines, suggesting that the screening-level guidelines will provide overly conservative assessments in most cases. Relevant spiked sediment toxicity data are very limited but seem consistent with the probabilistic model; additional testing could be conducted to confirm the model's predictions.

  9. Predator learning favours mimicry of a less-toxic model in poison frogs.

    PubMed

    Darst, Catherine R; Cummings, Molly E

    2006-03-09

    Batesian mimicry--resemblance of a toxic model by an edible mimic--depends on deceiving predators. Mimetic advantage is considered to be dependent on frequency because an increase in mimic abundance leads to breakdown of the warning signal. Where multiple toxic species are available, batesian polymorphism is predicted--that is, mimics diversify to match sympatric models. Despite the prevalence of batesian mimicry in nature, batesian polymorphism is relatively rare. Here we explore a poison-frog mimicry complex comprising two parapatric models and a geographically dimorphic mimic that shows monomorphism where models co-occur. Contrary to classical predictions, our toxicity assays, field observations and spectral reflectances show that mimics resemble the less-toxic and less-abundant model. We examine "stimulus generalization" as a mechanism for this non-intuitive result with learning experiments using naive avian predators and live poison frogs. We find that predators differ in avoidance generalization depending on toxicity of the model, conferring greater protection to mimics resembling the less-toxic model owing to overlap of generalized avoidance curves. Our work supports a mechanism of toxicity-dependent stimulus generalization, revealing an additional solution for batesian mimicry where multiple models coexist.

  10. Expanding metal mixture toxicity models to natural stream and lake invertebrate communities.

    PubMed

    Balistrieri, Laurie S; Mebane, Christopher A; Schmidt, Travis S; Keller, Wendel Bill

    2015-04-01

    A modeling approach that was used to predict the toxicity of dissolved single and multiple metals to trout is extended to stream benthic macroinvertebrates, freshwater zooplankton, and Daphnia magna. The approach predicts the accumulation of toxicants (H, Al, Cd, Cu, Ni, Pb, and Zn) in organisms using 3 equilibrium accumulation models that define interactions between dissolved cations and biological receptors (biotic ligands). These models differ in the structure of the receptors and include a 2-site biotic ligand model, a bidentate biotic ligand or 2-pKa model, and a humic acid model. The predicted accumulation of toxicants is weighted using toxicant-specific coefficients and incorporated into a toxicity function called Tox, which is then related to observed mortality or invertebrate community richness using a logistic equation. All accumulation models provide reasonable fits to metal concentrations in tissue samples of stream invertebrates. Despite the good fits, distinct differences in the magnitude of toxicant accumulation and biotic ligand speciation exist among the models for a given solution composition. However, predicted biological responses are similar among the models because there are interdependencies among model parameters in the accumulation-Tox models. To illustrate potential applications of the approaches, the 3 accumulation-Tox models for natural stream invertebrates are used in Monte Carlo simulations to predict the probability of adverse impacts in catchments of differing geology in central Colorado (USA); to link geology, water chemistry, and biological response; and to demonstrate how this approach can be used to screen for potential risks associated with resource development.

  11. Expanding metal mixture toxicity models to natural stream and lake invertebrate communities

    USGS Publications Warehouse

    Balistrieri, Laurie S.; Mebane, Christopher A.; Schmidt, Travis S.; Keller, William (Bill)

    2015-01-01

    A modeling approach that was used to predict the toxicity of dissolved single and multiple metals to trout is extended to stream benthic macroinvertebrates, freshwater zooplankton, and Daphnia magna. The approach predicts the accumulation of toxicants (H, Al, Cd, Cu, Ni, Pb, and Zn) in organisms using 3 equilibrium accumulation models that define interactions between dissolved cations and biological receptors (biotic ligands). These models differ in the structure of the receptors and include a 2-site biotic ligand model, a bidentate biotic ligand or 2-pKa model, and a humic acid model. The predicted accumulation of toxicants is weighted using toxicant-specific coefficients and incorporated into a toxicity function called Tox, which is then related to observed mortality or invertebrate community richness using a logistic equation. All accumulation models provide reasonable fits to metal concentrations in tissue samples of stream invertebrates. Despite the good fits, distinct differences in the magnitude of toxicant accumulation and biotic ligand speciation exist among the models for a given solution composition. However, predicted biological responses are similar among the models because there are interdependencies among model parameters in the accumulation–Tox models. To illustrate potential applications of the approaches, the 3 accumulation–Tox models for natural stream invertebrates are used in Monte Carlo simulations to predict the probability of adverse impacts in catchments of differing geology in central Colorado (USA); to link geology, water chemistry, and biological response; and to demonstrate how this approach can be used to screen for potential risks associated with resource development.

  12. A Physically Based Model for Air-Lift Pumping

    NASA Astrophysics Data System (ADS)

    FrançOis, Odile; Gilmore, Tyler; Pinto, Michael J.; Gorelick, Steven M.

    1996-08-01

    A predictive, physically based model for pumping water from a well using air injection (air-lift pumping) was developed for the range of flow rates that we explored in a series of laboratory experiments. The goal was to determine the air flow rate required to pump a specific flow rate of water in a given well, designed for in-well air stripping of volatile organic compounds from an aquifer. The model was validated against original laboratory data as well as data from the literature. A laboratory air-lift system was constructed that consisted of a 70-foot-long (21-m-long) pipe, 5.5 inches (14 cm) inside diameter, in which an air line of 1.3 inches (3.3 cm) outside diameter was placed with its bottom at different elevations above the base of the long pipe. Experiments were conducted for different levels of submergence, with water-pumping rates ranging from 5 to 70 gallons/min (0.32-4.4 L/s), and air flow ranging from 7 to 38 standard cubic feet/min (0.2-1.1 m3 STP/min). The theoretical approach adopted in the model was based on an analysis of the system as a one-dimensional two-phase flow problem. The expression for the pressure gradient includes inertial energy terms, friction, and gas expansion versus elevation. Data analysis revealed that application of the usual drift-flux model to estimate the air void fraction is not adequate for the observed flow patterns: either slug or churn flow. We propose a modified drift-flux model that accurately predicts air-lift pumping requirements for a range of conditions representative of in-well air-stripping operations.

  13. Linking Meteorology, Air Quality Models and Observations to ...

    EPA Pesticide Factsheets

    Epidemiologic studies are critical in establishing the association between exposure to air pollutants and adverse health effects. Results of epidemiologic studies are used by U.S. EPA in developing air quality standards to protect the public from the health effects of air pollutants. A major challenge in environmental epidemiology is adequate exposure characterization. Numerous health studies have used measurements from a few central-site ambient monitors to characterize air pollution exposures. Relying solely on central-site ambient monitors does not account for the spatial-heterogeneity of ambient air pollution patterns, the temporal variability in ambient concentrations, nor the influence of infiltration and indoor sources. Central-site monitoring becomes even more problematic for certain air pollutants that exhibit significant spatial heterogeneity. Statistical interpolation techniques and passive monitoring methods can provide additional spatial resolution in ambient concentration estimates. In addition, spatio-temporal models, which integrate GIS data and other factors, such as meteorology, have also been developed to produce more resolved estimates of ambient concentrations. Models, such as the Community Multi-Scale Air Quality (CMAQ) model, estimate ambient concentrations by combining information on meteorology, source emissions, and chemical-fate and transport. Hybrid modeling approaches, which integrate regional scale models with local scale dispersion

  14. Modeling air quality over China: Results from the Panda project

    NASA Astrophysics Data System (ADS)

    Katinka Petersen, Anna; Bouarar, Idir; Brasseur, Guy; Granier, Claire; Xie, Ying; Wang, Lili; Wang, Xuemei

    2015-04-01

    China faces strong air pollution problems related to rapid economic development in the past decade and increasing demand for energy. Air quality monitoring stations often report high levels of particle matter and ozone all over the country. Knowing its long-term health impacts, air pollution became then a pressing problem not only in China but also in other Asian countries. The PANDA project is a result of cooperation between scientists from Europe and China who joined their efforts for a better understanding of the processes controlling air pollution in China, improve methods for monitoring air quality and elaborate indicators in support of European and Chinese policies. A modeling system of air pollution is being setup within the PANDA project and include advanced global (MACC, EMEP) and regional (WRF-Chem, EMEP) meteorological and chemical models to analyze and monitor air quality in China. The poster describes the accomplishments obtained within the first year of the project. Model simulations for January and July 2010 are evaluated with satellite measurements (SCIAMACHY NO2 and MOPITT CO) and in-situ data (O3, CO, NOx, PM10 and PM2.5) observed at several surface stations in China. Using the WRF-Chem model, we investigate the sensitivity of the model performance to emissions (MACCity, HTAPv2), horizontal resolution (60km, 20km) and choice of initial and boundary conditions.

  15. Heme oxygenase-1 protects endothelial cells from the toxicity of air pollutant chemicals

    SciTech Connect

    Lawal, Akeem O.; Zhang, Min; Dittmar, Michael; Lulla, Aaron; Araujo, Jesus A.

    2015-05-01

    Diesel exhaust particles (DEPs) are a major component of diesel emissions, responsible for a large portion of their toxicity. In this study, we examined the toxic effects of DEPs on endothelial cells and the role of DEP-induced heme oxygenase-1 (HO-1) expression. Human microvascular endothelial cells (HMECs) were treated with an organic extract of DEPs from an automobile engine (A-DEP) or a forklift engine (F-DEP) for 1 and 4 h. ROS generation, cell viability, lactate dehydrogenase leakage, expression of HO-1, inflammatory genes, cell adhesion molecules and unfolded protein respone (UPR) gene were assessed. HO-1 expression and/or activity were inhibited by siRNA or tin protoporphyrin (Sn PPIX) and enhanced by an expression plasmid or cobalt protoporphyrin (CoPPIX). Exposure to 25 μg/ml of A-DEP and F-DEP significantly induced ROS production, cellular toxicity and greater levels of inflammatory and cellular adhesion molecules but to a different degree. Inhibition of HO-1 enzymatic activity with SnPPIX and silencing of the HO-1 gene by siRNA enhanced DEP-induced ROS production, further decreased cell viability and increased expression of inflammatory and cell adhesion molecules. On the other hand, overexpression of the HO-1 gene by a pcDNA 3.1D/V5-HO-1 plasmid significantly mitigated ROS production, increased cell survival and decreased the expression of inflammatory genes. HO-1 expression protected HMECs from DEP-induced prooxidative and proinflammatory effects. Modulation of HO-1 expression could potentially serve as a therapeutic target in an attempt to inhibit the cardiovascular effects of ambient PM. - Highlights: • We examined the role of HO-1 expression on diesel exhaust particle (DEP) in endothelial cells. • DEPs exert cytotoxic and inflammatory effects on human microvascular endothelial cells (HMECs). • DEPs induce HO-1 expression in HMECs. • HO-1 protects against the oxidative stress induced by DEps. • HO-1 attenuates the proinflammatory effects

  16. A Conceptual Framework for Predicting the Toxicity of Reactive Chemicals: Modeling Soft Electrophilicity

    EPA Science Inventory

    Although the literature is replete with QSAR models developed for many toxic effects caused by reversible chemical interactions, the development of QSARs for the toxic effects of reactive chemicals lacks a consistent approach. While limitations exit, an appropriate starting-point...

  17. Acute Electrocardiographic ST Segment Elevation May Predict Hypotension in a Swine Model of Severe Cyanide Toxicity

    DTIC Science & Technology

    2012-04-21

    induced shock, 30 swine were anesthetized and monitored and then intoxicated with a continuous cyanide infusion until severe hypotension (50 % of...TOXICOLOGY INVESTIGATION Acute Electrocardiographic ST Segment ElevationMay Predict Hypotension in a Swine Model of Severe Cyanide Toxicity Tylan A...Toxicology 2012 Abstract Cyanide causes severe cardiac toxicity resulting in tachycardia, hypotension, and cardiac arrest; however, the clinical diagnosis can

  18. MODELING APPROACHES FOR ESTIMATING THE DOSIMETRY OF INHALED TOXICANTS IN CHILDREN

    EPA Science Inventory

    Risk assessment of inhaled toxicants has typically focused upon adults, with modeling used to extrapolate dosimetry and risks from laboratory animals to humans. However, behavioral factors such as time spent playing outdoors can lead to more exposure to inhaled toxicants in chil...

  19. Development of biotic ligand models for chronic manganese toxicity to fish, invertebrates, and algae.

    PubMed

    Peters, Adam; Lofts, Stephen; Merrington, Graham; Brown, Bruce; Stubblefield, William; Harlow, Keven

    2011-11-01

    Ecotoxicity tests were performed with fish, invertebrates, and algae to investigate the effect of water quality parameters on Mn toxicity. Models were developed to describe the effects of Mn as a function of water quality. Calcium (Ca) has a protective effect on Mn toxicity for both fish and invertebrates, and magnesium (Mg) also provides a protective effect for invertebrates. Protons have a protective effect on Mn toxicity to algae. The models derived are consistent with models of the toxicity of other metals to aquatic organisms in that divalent cations can act as competitors to Mn toxicity in fish and invertebrates, and protons act as competitors to Mn toxicity in algae. The selected models are able to predict Mn toxicity to the test organisms to within a factor of 2 in most cases. Under low-pH conditions invertebrates are the most sensitive taxa, and under high-pH conditions algae are most sensitive. The point at which algae become more sensitive than invertebrates depends on the Ca concentration and occurs at higher pH when Ca concentrations are low, because of the sensitivity of invertebrates under these conditions. Dissolved organic carbon concentrations have very little effect on the toxicity of Mn to aquatic organisms.

  20. THE FUTURE OF COMPUTER-BASED TOXICITY PREDICTION: MECHANISM-BASED MODELS VS. INFORMATION MINING APPROACHES

    EPA Science Inventory


    The Future of Computer-Based Toxicity Prediction:
    Mechanism-Based Models vs. Information Mining Approaches

    When we speak of computer-based toxicity prediction, we are generally referring to a broad array of approaches which rely primarily upon chemical structure ...

  1. EFFECTS OF WATER CHEMISTRY ON COPPER TOXICITY - WHAT'S MISSING FROM CURRENT MODELS?

    EPA Science Inventory

    Current models for the acute toxicity of cationic metals to aquatic organisms focus on the binding of free metal ions to gill surfaces. This binding, and the resultant toxicity, can be reduced by metal-complexing ligands in the exposure water, which lower the activity of the free...

  2. Hybrid Air Quality Modeling Approach For Use in the Near ...

    EPA Pesticide Factsheets

    The Near-road EXposures to Urban air pollutant Study (NEXUS) investigated whether children with asthma living in close proximity to major roadways in Detroit, MI, (particularly near roadways with high diesel traffic) have greater health impacts associated with exposure to air pollutants than those living farther away. A major challenge in such health and exposure studies is the lack of information regarding pollutant exposure characterization. Air quality modeling can provide spatially and temporally varying exposure estimates for examining relationships between traffic-related air pollutants and adverse health outcomes. This paper presents a hybrid air quality modeling approach and its application in NEXUS in order to provide spatial and temporally varying exposure estimates and identification of the mobile source contribution to the total pollutant exposure. Model-based exposure metrics, associated with local variations of emissions and meteorology, were estimated using a combination of the AERMOD and R-LINE dispersion models, local emission source information from the National Emissions Inventory, detailed road network locations and traffic activity, and meteorological data from the Detroit City Airport. The regional background contribution was estimated using a combination of the Community Multiscale Air Quality (CMAQ) model and the Space/Time Ordinary Kriging (STOK) model. To capture the near-road pollutant gradients, refined “mini-grids” of model recep

  3. A FEDERATED PARTNERSHIP FOR URBAN METEOROLOGICAL AND AIR QUALITY MODELING

    EPA Science Inventory

    Recently, applications of urban meteorological and air quality models have been performed at resolutions on the order of km grid sizes. This necessitated development and incorporation of high resolution landcover data and additional boundary layer parameters that serve to descri...

  4. The Air Quality Model Evaluation International Initiative (AQMEII)

    EPA Science Inventory

    This presentation provides an overview of the Air Quality Model Evaluation International Initiative (AQMEII). It contains a synopsis of the three phases of AQMEII, including objectives, logistics, and timelines. It also provides a number of examples of analyses conducted through ...

  5. Incorporating principal component analysis into air quality model evaluation

    EPA Science Inventory

    The efficacy of standard air quality model evaluation techniques is becoming compromised as the simulation periods continue to lengthen in response to ever increasing computing capacity. Accordingly, the purpose of this paper is to demonstrate a statistical approach called Princi...

  6. Integration of Density Dependence and Concentration Response Models Provides an Ecologically Relevant Assessment of Populations Exposed to Toxicants

    EPA Science Inventory

    The assessment of toxic exposure on wildlife populations involves the integration of organism level effects measured in toxicity tests (e.g., chronic life cycle) and population models. These modeling exercises typically ignore density dependence, primarily because information on ...

  7. Development and application of air quality models at the US ...

    EPA Pesticide Factsheets

    Overview of the development and application of air quality models at the U.S. EPA, particularly focused on the development and application of the Community Multiscale Air Quality (CMAQ) model developed within the Computation Exposure Division (CED) of the National Exposure Research Laboratory (NERL). This presentation will provide a simple overview of air quality model development and application geared toward a non-technical student audience. The National Exposure Research Laboratory (NERL) Computational Exposure Division (CED) develops and evaluates data, decision-support tools, and models to be applied to media-specific or receptor-specific problem areas. CED uses modeling-based approaches to characterize exposures, evaluate fate and transport, and support environmental diagnostics/forensics with input from multiple data sources. It also develops media- and receptor-specific models, process models, and decision support tools for use both within and outside of EPA.

  8. Air quality model studies with application for southeastern Virginia

    NASA Technical Reports Server (NTRS)

    Brewer, D. A.; Remsberg, E. E.

    1980-01-01

    A single-cell photochemical air quality model incorporating (1) a published chemical mechanism, (2) advection, and (3) entrainment and emissions processes was constructed and compared with data from the EPA Regional Air Pollution Study. While agreement with measured CO and NO2 was established, O3 production was found to occur too rapidly and in excess. Calculated O3 levels improved when a 20% reduction in photolytic rate constants and a doubling of wind speed were applied. The results of the model sensitivity studies are being incorporated into the design and conduct of field measurement programs for the characterization of the vertical and horizontal homogeneity of an air quality region.

  9. Techniques for modeling hazardous air pollutant emissions from landfills

    SciTech Connect

    Lang, R.J.; Vigil, S.A.; Melcer, H.

    1998-12-31

    The Environmental Protection Agency`s Landfill Air Estimation Model (LAEEM), combined with either the AP-42 or CAA landfill emission factors, provide a basis to predict air emissions, including hazardous air pollutants (HAPs), from municipal solid waste landfills. This paper presents alternative approaches for estimating HAP emissions from landfills. These approaches include analytical solutions and estimation techniques that account for convection, diffusion, and biodegradation of HAPs. Results from the modeling of a prototypical landfill are used as the basis for discussion with respect to LAEEM results

  10. National Emission Standard for Hazardous Air Pollutants compliance verification plan for the K-1435 Toxic Substances Control Act Incinerator

    SciTech Connect

    Ambrose, M.L.

    1986-07-28

    This documentation was prepared for submittal to the Environmental Protection Agency (EPA) in order to meet the requirements of the National Emissions Standards for Hazardous Air Pollutants (NESHAP). This document will emphasize the control of radioactive emissions from the K-1435 Toxic Substances Control Act (TSCA) Incinerator. The TSCA Incinerator is a dual purpose solid/liquid incinerator that is under construction at the Oak Ridge Gaseous Diffusion Plant to destroy radioactively contaminated polychlorinated biphenyls (PCBs) and other hazardous organic wastes in compliance with the TSCA and the Resource Conservation and Recovery Act (RCRA). These wastes are generated at the facilities managed by the Department of Energy, Oak Ridge Operations (DOE-ORO). Destruction of the PCBs and the hazardous organic wastes will be accomplished in a rotary kiln incinerator with an afterburner. The incinerator will thermally destroy the organic constituents of the liquids, solids, and sludges to produce an organically inert ash. In addition to the incinerator, an extensive off-gas treatment facility is being constructed to remove particulate and acidic gas air emissions.

  11. VIRTUAL EMBRYO: SYSTEMS MODELING IN DEVELOPMENTAL TOXICITY - Symposium: SOT 2012

    EPA Science Inventory

    High-throughput screening (HTS) studies are providing a rich source of data that can be applied to in vitro profiling of chemical compounds for biological activity and potential toxicity. Chemical profiling in ToxCast covered 965 drugs-chemicals in over 500 diverse assays testing...

  12. Modeling interactions in major ion toxicity to Ceriodaphnia dubia

    EPA Science Inventory

    Various anthopogenic activities can cause exposures of freshwater systems to greatly elevated concentrations of major ions (Na, K, Ca, Mg, Cl, SO4, HCO3) with widely-varying compositions. A data set on the acute toxicity of single salts and binary salt mixtures to Ceriodaphnia d...

  13. Modeling interactions in major ion toxicity to Ceriodaphnia dubia (presentation)

    EPA Science Inventory

    Various anthropogenic activities can cause exposures of freshwater systems to greatly elevated concentrations of major ions (Na, K, Ca, Mg, Cl, SO4, HCO3) with widely-varying compositions. A data set on the acute toxicity of single salts and binary salt mixtures to Ceriodaphnia d...

  14. Predictive Modeling of Apical Toxicity Endpoints Using Data ...

    EPA Pesticide Factsheets

    The US EPA and other regulatory agencies face a daunting challenge of evaluating potential toxicity for tens of thousands of environmental chemicals about which little is currently known. The EPA’s ToxCast program is testing a novel approach to this problem by screening compounds using a variety of in vitro assays and using the results to prioritize chemicals for further, more detailed testing. Phase I of ToxCast is testing 320 chemicals (mainly pesticide active ingredients) against ~400 cell-based and biochemical assays. In order to anchor these studies, we are using in vivo guideline study data for subchronic, chronic, cancer, reproductive and developmental endpoints. This data is compiled in the EPA toxicity reference database, ToxRefDB. The main goal of ToxCast is the discovery and validation of “signatures” linking in vitro assay data to in vivo toxicity endpoints. These signatures will be collections of assays that are correlated with particular endpoints. These assay collections should also help define molecular-and cellular-level mechanisms of toxicity. This talk will discuss our strategy to use a combination of statistical and machine learning methods, coupled with biochemical network or systems biology approaches. Our initial examples will focus signatures for endpoints from 2 year rodent cancer bioassays. Most of the data we have analyzed is in dose or concentration response series, so to effectively use this data we have developed novel appro

  15. Exposure Space: Integrating Exposure Data and Modeling with Toxicity Information

    EPA Science Inventory

    Recent advances have been made in high-throughput (HTP) toxicity testing, e.g. from ToxCast, which will ultimately be combined with HTP predictions of exposure potential to support next-generation chemical safety assessment. Rapid exposure methods are essential in selecting chemi...

  16. Pathway Profiling and Tissue Modeling of Developmental Toxicity

    EPA Science Inventory

    High-throughput and high-content screening (HTS-HCS) studies are providing a rich source of data that can be applied to in vitro profiling of chemical compounds for biological activity and potential toxicity. EPA’s ToxCast™ project, and the broader Tox21 consortium, in addition t...

  17. Control of asthma triggers in indoor air with air cleaners: a modeling analysis

    PubMed Central

    Myatt, Theodore A; Minegishi, Taeko; Allen, Joseph G; MacIntosh, David L

    2008-01-01

    Background Reducing exposure to environmental agents indoors shown to increase asthma symptoms or lead to asthma exacerbations is an important component of a strategy to manage asthma for individuals. Numerous investigations have demonstrated that portable air cleaning devices can reduce concentrations of asthma triggers in indoor air; however, their benefits for breathing problems have not always been reproducible. The potential exposure benefits of whole house high efficiency in-duct air cleaners for sensitive subpopulations have yet to be evaluated. Methods We used an indoor air quality modeling system (CONTAM) developed by NIST to examine peak and time-integrated concentrations of common asthma triggers present in indoor air over a year as a function of natural ventilation, portable air cleaners, and forced air ventilation equipped with conventional and high efficiency filtration systems. Emission rates for asthma triggers were based on experimental studies published in the scientific literature. Results Forced air systems with high efficiency filtration were found to provide the best control of asthma triggers: 30–55% lower cat allergen levels, 90–99% lower risk of respiratory infection through the inhalation route of exposure, 90–98% lower environmental tobacco smoke (ETS) levels, and 50–75% lower fungal spore levels than the other ventilation/filtration systems considered. These results indicate that the use of high efficiency in-duct air cleaners provide an effective means of controlling allergen levels not only in a single room, like a portable air cleaner, but the whole house. Conclusion These findings are useful for evaluating potential benefits of high efficiency in-duct filtration systems for controlling exposure to asthma triggers indoors and for the design of trials of environmental interventions intended to evaluate their utility in practice. PMID:18684328

  18. Urban airshed modeling of air quality impacts of alternative transportation fuel use in Los Angeles and Atlanta

    SciTech Connect

    1997-12-01

    The main objective of NREL in supporting this study is to determine the relative air quality impact of the use of compressed natural gas (CNG) as an alternative transportation fuel when compared to low Reid vapor pressure (RVP) gasoline and reformulated gasoline (RFG). A table lists the criteria, air toxic, and greenhouse gas pollutants for which emissions were estimated for the alternative fuel scenarios. Air quality impacts were then estimated by performing photochemical modeling of the alternative fuel scenarios using the Urban Airshed Model Version 6.21 and the Carbon Bond Mechanism Version IV (CBM-IV) (Geary et al., 1988) Using this model, the authors examined the formation and transport of ozone under alternative fuel strategies for motor vehicle transportation sources for the year 2007. Photochemical modeling was performed for modeling domains in Los Angeles, California, and Atlanta, Georgia.

  19. Towards global QSAR model building for acute toxicity: Munro database case study.

    PubMed

    Chavan, Swapnil; Nicholls, Ian A; Karlsson, Björn C G; Rosengren, Annika M; Ballabio, Davide; Consonni, Viviana; Todeschini, Roberto

    2014-10-09

    A series of 436 Munro database chemicals were studied with respect to their corresponding experimental LD50 values to investigate the possibility of establishing a global QSAR model for acute toxicity. Dragon molecular descriptors were used for the QSAR model development and genetic algorithms were used to select descriptors better correlated with toxicity data. Toxic values were discretized in a qualitative class on the basis of the Globally Harmonized Scheme: the 436 chemicals were divided into 3 classes based on their experimental LD50 values: highly toxic, intermediate toxic and low to non-toxic. The k-nearest neighbor (k-NN) classification method was calibrated on 25 molecular descriptors and gave a non-error rate (NER) equal to 0.66 and 0.57 for internal and external prediction sets, respectively. Even if the classification performances are not optimal, the subsequent analysis of the selected descriptors and their relationship with toxicity levels constitute a step towards the development of a global QSAR model for acute toxicity.

  20. EnergyPlus Air Source Integrated Heat Pump Model

    SciTech Connect

    Shen, Bo; Adams, Mark B.; New, Joshua Ryan

    2016-03-30

    This report summarizes the development of the EnergyPlus air-source integrated heat pump model. It introduces its physics, sub-models, working modes, and control logic. In addition, inputs and outputs of the new model are described, and input data file (IDF) examples are given.

  1. CHANGES IN LUNG FUNCTION OBSERVED IN A STUDY OF PM AND AIR TOXICS EXPOSURE TO NC HIGHWAY PATROL TROOPERS (COPP-STUDY)

    EPA Science Inventory

    Introduction: Car emissions have been identified as a major source of respirable particles. Individuals whose jobs involve being on the road, such as patrol troopers, may be exposed to high cencentrations of toxic air pollutants from vehicle emissions. This exposure might a...

  2. REAL TIME, ON-LINE CHARACTERIZATION OF DIESEL GENERATOR AIR TOXIC EMISSIONS BY RESONANCE ENHANCED MULTI-PHOTON IONIZATION TIME OF FLIGHT MASS SPECTROMETRY

    EPA Science Inventory

    The laser based resonance, enhanced multi-photon ionization time-of-flight mass spectrometry (REMPI-TOFMS) technique has been applied to the exhaust gas stream of a diesel generator to measure, in real time, concentration levels of aromatic air toxics. Volatile organic compounds ...

  3. REAL-TIME EMISSION CHARACTERIZATION OF ORGANIC AIR TOXIC POLLUTANTS DURING STEADY STATE AND TRANSIENT OPERATION OF A MEDIUM DUTY DIESEL ENGINE

    EPA Science Inventory

    An on-line monitoring method, jet resonance-enhanced multi-photon ionization (REMPI) with time-of-flight mass spectrometry (TOFMS) was used to measure emissions of organic air toxics from a medium-duty (60 kW)diesel generator during transient and steady state operations. Emission...

  4. Characterization of air toxics from a laboratory coal-fired combustor

    SciTech Connect

    1995-04-03

    Emissions of hazardous air pollutants from coal combustion were studied in a laboratory-scale combustion facility, with emphasis on fine particles in three size ranges of less than 7.5 {mu}m diameter. Vapors were also measured. Substances under study included organic compounds, anions, elements, and radionuclides. Fly ash was generated by firing a bituminous coal in a combuster for 40 h at each of two coal feed rates. Flue gas was sampled under two conditions. Results for organic compounds, anions, and elements show a dependence on particle size consistent with published power plant data. Accumulation of material onto surface layers was inferred from differences in chemical composition between the plume simulating dilution sampler and hot flue samples. Extracts of organic particulate material were fractionated into different polarity fractions and analyzed by GC/MS. In Phase II, these laboratory results will be compared to emissions from a full-scale power plant burning the same coal.

  5. Auditing of sampling methods for air toxics at coal-fired power plants

    SciTech Connect

    Agbede, R.O.; Clements, J.L.; Grunebach, M.G.

    1995-11-01

    Advanced Technology Systems, Inc. (ATS) with subcontract assistance from international Technology Corporation (IT) has provided external audit activities for Phase II of the Department of Energy-Pittsburgh Energy Technology Center`s air emission test program. The objective of the audits is to help ensure that the data obtained from the emission tests are precise, accurate, representative, scientifically sound and legally defensible. This paper presents the criteria that were used to perform the external audits of the emission test program. It also describes the approach used by ATS and It in performing their audits. Examples of findings of the audits along with the actions take to correct problems and the subsequent effect of those actions on the test data are presented. The results of audit spikes performed at the Plant 1 test site are also discussed.

  6. Sampling of power plant stacks for air toxic emissions: Topical report for Phases 1 and 2

    SciTech Connect

    1995-02-21

    Under contract with the US Department of Energy (DE-AC22-92PCO0367), Pittsburgh Energy Technology Center, Radian Corporation has conducted a test program to collect and analyze size-fractionated stack gas particulate samples for selected inorganic hazardous air pollutants (HAPS). Specific goals of the program are (1) the collection of one-gram quantities of size-fractionated stack gas particulate matter for bulk (total) and surface chemical charactization, and (2) the determination of the relationship between particle size, bulk and surface (leachable) composition, and unit load. The information obtained from this program identifies the effects of unit load, particle size, and wet FGD system operation on the relative toxicological effects of exposure to particulate emissions.

  7. Emissions of air toxics from a simulated charcoal kiln. Final report, October 1997--September 1998

    SciTech Connect

    Lemieux, P.M.

    1999-06-01

    The report gives results of experiments in a laboratory-scale charcoal kiln simulator to evaluate emissions of hazardous air pollutants from the production of charcoal in Missouri-type kilns. Fixed combustion gases were measured using continuous monitors. In addition, other pollutants, including methanol, volatile organic compounds, semivolatile organic compounds, and particle emission rates and size distributions were measured using various techniques. Emissions of all pollutants are reported in units of grams emitted per unit mass of initial wood converted to charcoal. Two burn conditions--slow and fast--were examined. High levels of methanol, benzene, and fine particulate were emitted in all tests. The estimated emissions from the fast burn conditions were significantly higher than those from the slow burn conditions.

  8. Emissions of air toxics from the production of charcoal in a simulated Missouri charcoal kiln

    SciTech Connect

    Lemieux, P.M.; Kariher, P.H.; Fairless, B.J.; Tapp, J.A.

    1998-11-01

    The paper gives results of experiments in a laboratory-scale charcoal kiln simulator to evaluate emissions of hazardous air pollutant from the production of charcoal in Missouri-type kilns. Fixed combustion gases were measured using continuous monitors. In addition, other pollutants, including methanol, volatile organic compounds, semivolatile organic compounds, and particle emission rates and size distributions were measured using various techniques. Emissions of all pollutants are reported in grams emitted per unit mass of initial wood converted to charcoal. Two burn conditions--slow and fast burn--were examined. High levels of methanol, benzene, and fine particulate were emitted from all tests. The estimated emissions from the fast burn conditions were significantly higher than those from the slow burn conditions.

  9. Biofiltration control of VOC and air toxic emissions: n-Butane and benzene

    SciTech Connect

    Allen, E.R.

    1996-12-31

    n-Butane and benzene vapors are routinely observed in urban atmospheres. Their presence in urban airsheds is of concern because of their ozone production potential as volatile organic compounds (VOCs) and/or potential toxicity. Also, these saturated hydrocarbons are representative of airborne aliphatic and aromatic compounds. Separate laboratory studies have been conducted on the biological elimination of n-butane (n-C{sub 4}H{sub 10}) and benzene (C{sub 6}H{sub 6}) from airstreams using treated compost biofilters. The removal efficiencies were found to exceed 90% for a conditioned biofilter medium and pollutant low concentrations (< 25 ppm) and zeroth order kinetics at higher concentrations (> 100 ppm), whereas benzene vapor elimination followed zeroth order kinetics at concentrations up to 200 ppm. The maximum n-butane and benzene elimination capacities observed for the compost biofilters and conditions employed were 25 and 70 g pollutant m{sup -3} h{sup -1}, respectively. 13 refs., 6 figs., 2 tabs.

  10. Benzene toxicity of the occurrence of benzene in the ambient air of the Houston area

    SciTech Connect

    Lin, Y.C.

    1980-01-01

    This study was conducted by either literature review or actual field survey. Results are summarized as follows: (1) long-term occupational exposure of workers to benzene vapor at levels of 3 to 7 ppM, 2 to 3 ppM and 1.6 ppM may result in a decreased level of leucocyte alkaline phosphates, an increased incidence of chromosome aberrations and an increased level of ALA in erythrocytes, respectively; (2) benzene is capable of causing fetotoxic effects in animals at levels as low as 10 ppM by volume; (3) exposure of animals to or less than 1 ppM benzene vapor may result in leucopenia, an inverse ratio of muscle antagonist chronaxy and a decreased level of ascorbic acid in fetus's and mother's liver as well as whole embryo; (4) benzene is causally associated with the increased incidence of pancytopenia, including unicytopenia, bicytopenia and aplastic anemia, and chromosome aberrations in occupational exposure population, and at best benzene must also be considered as a leukemogen; (5) since it can be emitted into the atmosphere from both man-made and natural sources, benzene in some concentrations is presented everywhere in the various compartments of the environment; (6) the findings of the emission of benzene from certain natural sources indicate that reducing benzene to a zero-level of exposure is theoretically impossible; (7) the annual average of benzene concentration detected in the Houston ambient air is 2.50 ppB, which is about 2.4 times higher than the nation-wide annual average exposure level and may have some health implications to the general public; and (8) in the Houston area, stationary sources are more important than mobile sources in contributing to benzene in the ambient air.

  11. Optimization of an air-liquid interface exposure system for assessing toxicity of airborne nanoparticles.

    PubMed

    Latvala, Siiri; Hedberg, Jonas; Möller, Lennart; Odnevall Wallinder, Inger; Karlsson, Hanna L; Elihn, Karine

    2016-10-01

    The use of refined toxicological methods is currently needed for characterizing the risks of airborne nanoparticles (NPs) to human health. To mimic pulmonary exposure, we have developed an air-liquid interface (ALI) exposure system for direct deposition of airborne NPs on to lung cell cultures. Compared to traditional submerged systems, this allows more realistic exposure conditions for characterizing toxicological effects induced by airborne NPs. The purpose of this study was to investigate how the deposition of silver NPs (AgNPs) is affected by different conditions of the ALI system. Additionally, the viability and metabolic activity of A549 cells was studied following AgNP exposure. Particle deposition increased markedly with increasing aerosol flow rate and electrostatic field strength. The highest amount of deposited particles (2.2 μg cm(-2) ) at cell-free conditions following 2 h exposure was observed for the highest flow rate (390 ml min(-1) ) and the strongest electrostatic field (±2 kV). This was estimated corresponding to deposition efficiency of 94%. Cell viability was not affected after 2 h exposure to clean air in the ALI system. Cells exposed to AgNPs (0.45 and 0.74 μg cm(-2) ) showed significantly (P < 0.05) reduced metabolic activities (64 and 46%, respectively). Our study shows that the ALI exposure system can be used for generating conditions that were more realistic for in vitro exposures, which enables improved mechanistic and toxicological studies of NPs in contact with human lung cells.Copyright © 2016 The Authors Journal of Applied Toxicology Published by John Wiley & Sons Ltd.

  12. Modelling heat and mass transfer in a membrane-based air-to-air enthalpy exchanger

    NASA Astrophysics Data System (ADS)

    Dugaria, S.; Moro, L.; Del, D., Col

    2015-11-01

    The diffusion of total energy recovery systems could lead to a significant reduction in the energy demand for building air-conditioning. With these devices, sensible heat and humidity can be recovered in winter from the exhaust airstream, while, in summer, the incoming air stream can be cooled and dehumidified by transferring the excess heat and moisture to the exhaust air stream. Membrane based enthalpy exchangers are composed by different channels separated by semi-permeable membranes. The membrane allows moisture transfer under vapour pressure difference, or water concentration difference, between the two sides and, at the same time, it is ideally impermeable to air and other contaminants present in exhaust air. Heat transfer between the airstreams occurs through the membrane due to the temperature gradient. The aim of this work is to develop a detailed model of the coupled heat and mass transfer mechanisms through the membrane between the two airstreams. After a review of the most relevant models published in the scientific literature, the governing equations are presented and some simplifying assumptions are analysed and discussed. As a result, a steady-state, two-dimensional finite difference numerical model is setup. The developed model is able to predict temperature and humidity evolution inside the channels. Sensible and latent heat transfer rate, as well as moisture transfer rate, are determined. A sensitive analysis is conducted in order to determine the more influential parameters on the thermal and vapour transfer.

  13. Air Leakage of U.S. Homes: Model Prediction

    SciTech Connect

    Sherman, Max H.; McWilliams, Jennifer A.

    2007-01-01

    Air tightness is an important property of building envelopes. It is a key factor in determining infiltration and related wall-performance properties such as indoor air quality, maintainability and moisture balance. Air leakage in U.S. houses consumes roughly 1/3 of the HVAC energy but provides most of the ventilation used to control IAQ. The Lawrence Berkeley National Laboratory has been gathering residential air leakage data from many sources and now has a database of more than 100,000 raw measurements. This paper uses a model developed from that database in conjunction with US Census Bureau data for estimating air leakage as a function of location throughout the US.

  14. A diagnostic model for studying daytime urban air quality trends

    NASA Technical Reports Server (NTRS)

    Brewer, D. A.; Remsberg, E. E.; Woodbury, G. E.

    1981-01-01

    A single cell Eulerian photochemical air quality simulation model was developed and validated for selected days of the 1976 St. Louis Regional Air Pollution Study (RAPS) data sets; parameterizations of variables in the model and validation studies using the model are discussed. Good agreement was obtained between measured and modeled concentrations of NO, CO, and NO2 for all days simulated. The maximum concentration of O3 was also predicted well. Predicted species concentrations were relatively insensitive to small variations in CO and NOx emissions and to the concentrations of species which are entrained as the mixed layer rises.

  15. CAirTOX, An inter-media transfer model for assessing indirect exposures to hazardous air contaminants

    SciTech Connect

    McKone, T.E.

    1994-01-01

    Risk assessment is a quantitative evaluation of information on potential health hazards of environmental contaminants and the extent of human exposure to these contaminants. As applied to toxic chemical emissions to air, risk assessment involves four interrelated steps. These are (1) determination of source concentrations or emission characteristics, (2) exposure assessment, (3) toxicity assessment, and (4) risk characterization. These steps can be carried out with assistance from analytical models in order to estimate the potential risk associated with existing and future releases. CAirTOX has been developed as a spreadsheet model to assist in making these types of calculations. CAirTOX follows an approach that has been incorporated into the CalTOX model, which was developed for the California Department of Toxic Substances Control, With CAirTOX, we can address how contaminants released to an air basin can lead to contamination of soil, food, surface water, and sediments. The modeling effort includes a multimedia transport and transformation model, exposure scenario models, and efforts to quantify uncertainty in multimedia, multiple-pathway exposure assessments. The capacity to explicitly address uncertainty has been incorporated into the model in two ways. First, the spreadsheet form of the model makes it compatible with Monte-Carlo add-on programs that are available for uncertainty analysis. Second, all model inputs are specified in terms of an arithmetic mean and coefficient of variation so that uncertainty analyses can be carried out.

  16. Development of Novel Models for Describing Multiple Toxicity Effects

    DTIC Science & Technology

    1994-10-12

    The data set used was one involving exposure of rats to two liver carcinogens - LAS (an aflatoxin ) and CYCA (a food contaminant) reported by NCI...assumptions regarding mixture toxicity. Essentially , many individuals, as well as current regulatory practice, believe that although mixture interactive... Aflatoxin B I in Rats Journal of the National Cancer Institute, 53, 2 453-458 (1974). compounds studied: Cyclopropenoid, Aflatoxin B, Diethylnitrosamine

  17. Semiconductor quantum dot toxicity in a mouse in vivo model

    NASA Astrophysics Data System (ADS)

    Bozrova, Svetlana V.; Baryshnikova, Maria A.; Nabiev, Igor; Sukhanova, Alyona

    2017-01-01

    Quantum dots (QDs) are increasingly widely used in clinical medicine. Their most promising potential applications are cancer diagnosis, including in vivo tumour imaging and targeted drug delivery. In this connection, the main questions are whether or not QDs are toxic for humans and, if they are, what concentration is relatively harmless. We have carried out in vivo experiments with CdSe/ZnS fluorescent semiconductor core/shell QDs, which are currently the most widely used in research.

  18. The Texas-Indiana Virtual STAR Center: Zebrafish Models for Developmental Toxicity Screening

    EPA Pesticide Factsheets

    The Texas-Indiana Virtual STAR Center: Zebrafish Models for Developmental Toxicity Screening (Presented by Maria Bondesson Bolin, Ph.D, University of Houston, Center for Nuclear Receptors and Cell Signaling) (3/22/2012)

  19. Integration into Big Data: First Steps to Support Reuse of Comprehensive Toxicity Model Modules (SOT)

    EPA Science Inventory

    Data surrounding the needs of human disease and toxicity modeling are largely siloed limiting the ability to extend and reuse modules across knowledge domains. Using an infrastructure that supports integration across knowledge domains (animal toxicology, high-throughput screening...

  20. ESTIMATION OF CHEMICAL TOXICITY TO WILDLIFE SPECIES USING INTERSPECIES CORRELATION MODELS

    EPA Science Inventory

    Ecological risks to wildlife are typically assessed using toxicity data for relataively few species and with limited understanding of differences in species sensitivity to contaminants. Empirical interspecies correlation models were derived from LD50 values for 49 wildlife speci...

  1. Community Multiscale Air Quality (CMAQ) Modeling for ...

    EPA Pesticide Factsheets

    The CMAQ model is a Eulerian model that produces gridded values of atmospheric concentration and deposition. Recent updates to the model are highlighted that impact estimates of dry and wet deposition of nitrogen, sulfur and base cations. Output from the CMAQ model is used in the measurement-model fusion method used to create the National Atmospheric Program's (NADP) Total Deposition (TDEP) map product. The National Exposure Research Laboratory (NERL) Computational Exposure Division (CED) develops and evaluates data, decision-support tools, and models to be applied to media-specific or receptor-specific problem areas. CED uses modeling-based approaches to characterize exposures, evaluate fate and transport, and support environmental diagnostics/forensics with input from multiple data sources. It also develops media- and receptor-specific models, process models, and decision support tools for use both within and outside of EPA.

  2. Toxicity of thiocyanate, phenol, and their mixtures to freshwater aquatic organisms: A mixture modeling approach

    SciTech Connect

    Soboslay, E.G.

    1987-01-01

    Thiocyanate and phenol are two environmentally significant constituents of wastewater streams from coke production plants and coal conversion facilities. Acute and chronic toxicity experiments were conducted for thiocyanate and phenol with Daphnia magna at 20 C and Ceriodaphnia affinis/dubia at 25C in hard water to study their individual toxic effects on survival and reproduction. Statistical analysis of the dose response relationships for the individual chemicals indicated the type of combined effects that occur when thiocyanate and phenol are present simultaneously. Mixture models for toxicant interaction were used to predict joint toxic effects on survival and reproduction. The applicability of the mixture model was tested by performing joint toxicity experiments for specific thiocyanate and phenol mixtures to verify the model for toxic effects on specific whole organism performances. Neonate production and hatchability, two indices of reproduction, were selected to evaluate the chronic toxic effects of thiocyanate and phenol. The resulting dose response curves for mixtures were compared to curves predicted on the basis of the mathematical model for concentration addition. Low concentrations of thiocyanate, phenol and their mixtures generally caused a stimulation effect on D. magna and C. affinis/dubia reproduction.

  3. The ASAC Air Carrier Investment Model (Third Generation)

    NASA Technical Reports Server (NTRS)

    Wingrove, Earl R., III; Gaier, Eric M.; Santmire, Tara E.

    1998-01-01

    To meet its objective of assisting the U.S. aviation industry with the technological challenges of the future, NASA must identify research areas that have the greatest potential for improving the operation of the air transportation system. To accomplish this, NASA is building an Aviation System Analysis Capability (ASAC). The ASAC differs from previous NASA modeling efforts in that the economic behavior of buyers and sellers in the air transportation and aviation industries is central to its conception. To link the economics of flight with the technology of flight, ASAC requires a parametrically based model with extensions that link airline operations and investments in aircraft with aircraft characteristics. This model also must provide a mechanism for incorporating air travel demand and profitability factors into the airlines' investment decisions. Finally, the model must be flexible and capable of being incorporated into a wide-ranging suite of economic and technical models flat are envisioned for ASAC.

  4. Modeling the toxicity of aromatic compounds to tetrahymena pyriformis: the response surface methodology with nonlinear methods.

    PubMed

    Ren, Shijin

    2003-01-01

    Response surface models based on multiple linear regression had previously been developed for the toxicity of aromatic chemicals to Tetrahymena pyriformis. However, a nonlinear relationship between toxicity and one of the molecular descriptors in the response surface model was observed. In this study, response surface models were established using six nonlinear modeling methods to handle the nonlinearity exhibited in the aromatic chemicals data set. All models were validated using the method of cross-validation, and prediction accuracy was tested on an external data set. Results showed that response surface models based on locally weighted regression scatter plot smoothing (LOESS), multivariate adaptive regression splines (MARS), neural networks (NN), and projection pursuit regression (PPR) provided satisfactory power of model fitting and prediction and had similar applicabilities. The response surface models based on nonlinear methods were difficult to interpret and conservative in discriminating toxicity mechanisms.

  5. Development of a model for radon concentration in indoor air.

    PubMed

    Jelle, Bjørn Petter

    2012-02-01

    A model is developed for calculation of the radon concentration in indoor air. The model takes into account various important parameters, e.g. radon concentration in ground, radon diffusion resistance of radon barrier, air permeance of ground, air pressure difference between outdoor ground and indoor at ground level, ventilation of the building ground and number of air changes per hour due to ventilation. Characteristic case studies are depicted in selected 2D and 3D graphical plots for easy visualization and interpretation. The radon transport into buildings might be dominated by diffusion, pressure driven flow or a mixture of both depending on the actual values of the various parameters. The results of our work indicate that with realistic or typical values of the parameters, most of the transport of radon from the building ground to the indoor air is due to air leakage driven by pressure differences through the construction. By incorporation of various and realistic values in the radon model, valuable information about the miscellaneous parameters influencing the indoor radon level is gained. Hence, the presented radon model may be utilized as a simple yet versatile and powerful tool for examining which preventive or remedial measures should be carried out to achieve an indoor radon level below the reference level as set by the authorities.

  6. Development of a new toxic-unit model for the bioassessment of metals in streams.

    PubMed

    Schmidt, Travis S; Clements, William H; Mitchell, Katharine A; Church, Stanley E; Wanty, Richard B; Fey, David L; Verplanck, Philip L; San Juan, Carma A

    2010-11-01

    Two toxic-unit models that estimate the toxicity of trace-metal mixtures to benthic communities were compared. The chronic criterion accumulation ratio (CCAR), a modification of biotic ligand model (BLM) outputs for use as a toxic-unit model, accounts for the modifying and competitive influences of major cations (Ca²(+), Mg²(+), Na(+), K(+), H(+)), anions (HCO₃⁻, CO²⁻₃ ,SO²⁻₄, Cl⁻, S²⁻) and dissolved organic carbon (DOC) in determining the free metal ion available for accumulation on the biotic ligand. The cumulative criterion unit (CCU) model, an empirical statistical model of trace-metal toxicity, considers only the ameliorative properties of Ca²(+) and Mg²(+) (hardness) in determining the toxicity of total dissolved trace metals. Differences in the contribution of a metal (e.g., Cu, Cd, Zn) to toxic units as determined by CCAR or CCU were observed and attributed to how each model incorporates the influences of DOC, pH, and alkalinity. Akaike information criteria demonstrate that CCAR is an improved predictor of benthic macroinvertebrate community metrics as compared with CCU. Piecewise models depict great declines (thresholds) in benthic macroinvertebrate communities at CCAR of 1 or more, while negative changes in benthic communities were detected at a CCAR of less than 1. We observed a 7% reduction in total taxa richness and a 43% decrease in Heptageniid abundance between background (CCAR = 0.1) and the threshold of chronic toxicity on the basis of continuous chronic criteria (CCAR = 1). In this first application of the BLM as a toxic-unit model, we found it superior to CCU.

  7. Development of a new toxic-unit model for the bioassessment of metals in streams

    USGS Publications Warehouse

    Schmidt, T.S.; Clements, W.H.; Mitchell, K.A.; Church, S.E.; Wanty, R.B.; Fey, D.L.; Verplanck, P.L.; San, Juan C.A.

    2010-01-01

    Two toxic-unit models that estimate the toxicity of trace-metal mixtures to benthic communities were compared. The chronic criterion accumulation ratio (CCAR), a modification of biotic ligand model (BLM) outputs for use as a toxic-unit model, accounts for the modifying and competitive influences of major cations (Ca2+, Mg2+, Na+, K+, H+), anions (HCO3−, CO32−,SO42−, Cl−, S2−) and dissolved organic carbon (DOC) in determining the free metal ion available for accumulation on the biotic ligand. The cumulative criterion unit (CCU) model, an empirical statistical model of trace-metal toxicity, considers only the ameliorative properties of Ca2+ and Mg2+ (hardness) in determining the toxicity of total dissolved trace metals. Differences in the contribution of a metal (e.g., Cu, Cd, Zn) to toxic units as determined by CCAR or CCU were observed and attributed to how each model incorporates the influences of DOC, pH, and alkalinity. Akaike information criteria demonstrate that CCAR is an improved predictor of benthic macroinvertebrate community metrics as compared with CCU. Piecewise models depict great declines (thresholds) in benthic macroinvertebrate communities at CCAR of 1 or more, while negative changes in benthic communities were detected at a CCAR of less than 1. We observed a 7% reduction in total taxa richness and a 43% decrease in Heptageniid abundance between background (CCAR = 0.1) and the threshold of chronic toxicity on the basis of continuous chronic criteria (CCAR = 1). In this first application of the BLM as a toxic-unit model, we found it superior to CCU.

  8. Scale Issues in Air Quality Modeling

    EPA Science Inventory

    This presentation reviews past model evaluation studies investigating the impact of horizontal grid spacing on model performance. It also presents several examples of using a spectral decomposition technique to separate the forcings from processes operating on different time scal...

  9. Evaluation of regional climate simulations for air quality modelling purposes

    NASA Astrophysics Data System (ADS)

    Menut, Laurent; Tripathi, Om P.; Colette, Augustin; Vautard, Robert; Flaounas, Emmanouil; Bessagnet, Bertrand

    2013-05-01

    In order to evaluate the future potential benefits of emission regulation on regional air quality, while taking into account the effects of climate change, off-line air quality projection simulations are driven using weather forcing taken from regional climate models. These regional models are themselves driven by simulations carried out using global climate models (GCM) and economical scenarios. Uncertainties and biases in climate models introduce an additional "climate modeling" source of uncertainty that is to be added to all other types of uncertainties in air quality modeling for policy evaluation. In this article we evaluate the changes in air quality-related weather variables induced by replacing reanalyses-forced by GCM-forced regional climate simulations. As an example we use GCM simulations carried out in the framework of the ERA-interim programme and of the CMIP5 project using the Institut Pierre-Simon Laplace climate model (IPSLcm), driving regional simulations performed in the framework of the EURO-CORDEX programme. In summer, we found compensating deficiencies acting on photochemistry: an overestimation by GCM-driven weather due to a positive bias in short-wave radiation, a negative bias in wind speed, too many stagnant episodes, and a negative temperature bias. In winter, air quality is mostly driven by dispersion, and we could not identify significant differences in either wind or planetary boundary layer height statistics between GCM-driven and reanalyses-driven regional simulations. However, precipitation appears largely overestimated in GCM-driven simulations, which could significantly affect the simulation of aerosol concentrations. The identification of these biases will help interpreting results of future air quality simulations using these data. Despite these, we conclude that the identified differences should not lead to major difficulties in using GCM-driven regional climate simulations for air quality projections.

  10. Modeling of lead air pollution. [Baton Rouge, Louisiana

    SciTech Connect

    Monteith, C.S.; Henry, J.M.

    1982-05-01

    A study was performed to determine whether vehicular emissions should be included with industrial emissions when demonstrating attainment of the ambient air quality standard for lead. The impact on ambient lead concentrations of the phaseout of leaded gasoline and improved automobile fuel economy was examined by modeling vehicular emissions for 1972 and 1978. Results show that while automobiles in the Baton Rouge area were a significant source of lead in 1972, the phaseout of leaded gasoline and the increase in fuel economy have resulted in a lower contribution (0.20 ..mu..g/m/sup 3/) by automobiles to the ambient lead concentration in 1978. The areas having the greatest potential for exceeding the ambient air quality standard can be identified using CDM (EPA's Climatological Dispersion Model). This information can be used to determine the optimal location for an ambient air monitor to demonstrate compliance with the ambient air quality standard. 9 references, 4 figures, 5 tables. (JMT)

  11. Developing of a New Atmospheric Ionizing Radiation (AIR) Model

    NASA Technical Reports Server (NTRS)

    Clem, John M.; deAngelis, Giovanni; Goldhagen, Paul; Wilson, John W.

    2003-01-01

    As a result of the research leading to the 1998 AIR workshop and the subsequent analysis, the neutron issues posed by Foelsche et al. and further analyzed by Hajnal have been adequately resolved. We are now engaged in developing a new atmospheric ionizing radiation (AIR) model for use in epidemiological studies and air transportation safety assessment. A team was formed to examine a promising code using the basic FLUKA software but with modifications to allow multiple charged ion breakup effects. A limited dataset of the ER-2 measurements and other cosmic ray data will be used to evaluate the use of this code.

  12. The ASAC Air Carrier Investment Model (Second Generation)

    NASA Technical Reports Server (NTRS)

    Wingrove, Earl R., III; Johnson, Jesse P.; Sickles, Robin C.; Good, David H.

    1997-01-01

    To meet its objective of assisting the U.S. aviation industry with the technological challenges of the future, NASA must identify research areas that have the greatest potential for improving the operation of the air transportation system. To accomplish this, NASA is building an Aviation System Analysis Capability (ASAC). The ASAC differs from previous NASA modeling efforts in that the economic behavior of buyers and sellers in the air transportation and aviation industries is central to its conception. To link the economics of flight with the technology of flight, ASAC requires a parametrically based mode with extensions that link airline operations and investments in aircraft with aircraft characteristics. This model also must provide a mechanism for incorporating air travel demand and profitability factors into the airlines' investment decisions. Finally, the model must be flexible and capable of being incorporated into a wide-ranging suite of economic and technical models that are envisioned for ASAC. We describe a second-generation Air Carrier Investment Model that meets these requirements. The enhanced model incorporates econometric results from the supply and demand curves faced by U.S.-scheduled passenger air carriers. It uses detailed information about their fleets in 1995 to make predictions about future aircraft purchases. It enables analysts with the ability to project revenue passenger-miles flown, airline industry employment, airline operating profit margins, numbers and types of aircraft in the fleet, and changes in aircraft manufacturing employment under various user-defined scenarios.

  13. Sampling of power plant stacks for air toxic emissions: Final report for Phases 1 and 2

    SciTech Connect

    1995-04-28

    A test program to collect and analyze size-fractionated stack gas particulate samples for selected inorganic hazardous air pollutants (HAPs) was conducted . Specific goals of the program are (1) the collection of one-gram quantities of size-fractionated stack gas particulate matter for bulk (total) and surface chemical characterization, and (2) the determination of the relationship between particle size, bulk and surface (leachable) composition, and unit load. The information obtained from this program identifies the effects of unit load, particle size, and wet FGD system operation on the relative toxicological effects of exposure to particulate emissions. Field testing was conducted in two phases. The Phase I field program was performed over the period of August 24 through September 20, 1992, at the Tennessee Valley Authority Widows Creek Unit 8 Power Station, located near Stevenson (Jackson County), Alabama, on the Tennessee River. Sampling activities for Phase II were conducted from September 11 through October 14, 1993. Widows Creek Unit 8 is a 575-megawatt plant that uses bituminous coal averaging 3.7% sulfur and 13% ash. Downstream of the boiler, a venture wet scrubbing system is used for control of both sulfur dioxide and particulate emissions. There is no electrostatic precipitator (ESP) in this system. This system is atypical and represents only about 5% of the US utility industry. However, this site was chosen for this study because of the lack of information available for this particulate emission control system.

  14. Modeling air temperature changes in Northern Asia

    NASA Astrophysics Data System (ADS)

    Onuchin, A.; Korets, M.; Shvidenko, A.; Burenina, T.; Musokhranova, A.

    2014-11-01

    Based on time series (1950-2005) of monthly temperatures from 73 weather stations in Northern Asia (limited by 70-180° EL and 48-75° NL), it is shown that there are statistically significant spatial differences in character and intensity of the monthly and yearly temperature trends. These differences are defined by geomorphological and geographical parameters of the area including exposure of the territory to Arctic and Pacific air mass, geographic coordinates, elevation, and distances to Arctic and Pacific oceans. Study area has been divided into six domains with unique groupings of the temperature trends based on cluster analysis. An original methodology for mapping of temperature trends has been developed and applied to the region. The assessment of spatial patterns of temperature trends at the regional level requires consideration of specific regional features in the complex of factors operating in the atmosphere-hydrosphere-lithosphere-biosphere system.

  15. Air Quality Modeling in Support of the Near-Road Exposures and Effects of Urban Air Pollutants Study (NEXUS)

    EPA Science Inventory

    A major challenge in traffic-related air pollution exposure studies is the lack of information regarding pollutant exposure characterization. Air quality modeling can provide spatially and temporally varying exposure estimates for examining relationships between traffic-related a...

  16. Probabilistic ecological risk assessment of effluent toxicity of a wastewater reclamation plant based on process modeling.

    PubMed

    Zeng, Siyu; Huang, Yunqing; Sun, Fu; Li, Dan; He, Miao

    2016-09-01

    The growing use of reclaimed wastewater for environmental purposes such as stream flow augmentation requires comprehensive ecological risk assessment and management. This study applied a system analysis approach, regarding a wastewater reclamation plant (WRP) and its recipient water body as a whole system, and assessed the ecological risk of the recipient water body caused by the WRP effluent. Instead of specific contaminants, two toxicity indicators, i.e. genotoxicity and estrogenicity, were selected to directly measure the biological effects of all bio-available contaminants in the reclaimed wastewater, as well as characterize the ecological risk of the recipient water. A series of physically based models were developed to simulate the toxicity indicators in a WRP through a typical reclamation process, including ultrafiltration, ozonation, and chlorination. After being validated against the field monitoring data from a full-scale WRP in Beijing, the models were applied to simulate the probability distribution of effluent toxicity of the WRP through Latin Hypercube Sampling to account for the variability of influent toxicity and operation conditions. The simulated effluent toxicity was then used to derive the predicted environmental concentration (PEC) in the recipient stream, considering the variations of the toxicity and flow of the upstream inflow as well. The ratio of the PEC of each toxicity indicator to its corresponding predicted no-effect concentration was finally used for the probabilistic ecological risk assessment. Regional sensitivity analysis was also performed with the developed models to identify the critical control variables and strategies for ecological risk management.

  17. Metal toxicity, uptake and bioaccumulation in aquatic invertebrates--modelling zinc in crustaceans.

    PubMed

    Rainbow, P S; Luoma, S N

    2011-10-01

    We use published data on the different patterns of the bioaccumulation of zinc by three crustaceans, the caridean decapod Palaemon elegans, the amphipod Orchestia gammarellus and the barnacle Amphibalanus amphitrite, to construct comparative biodynamic models of the bioaccumulation of zinc into metabolically available and detoxified components of accumulated zinc in each crustacean under both field and laboratory toxicity test conditions. We then link these bioaccumulation models to the onset of toxic effects on exposure of the crustaceans to high dissolved zinc bioavailabilities, using the tenets that toxicity effects are related to the total uptake rate of the toxic metal, and that toxicity is not usually dependent on the total accumulated metal concentration but always on the concentration of accumulated metal that is metabolically available. We dismiss the general concept that there is a critical accumulated body concentration of a metal in an invertebrate at which toxicity ensues, except under specific circumstances involving a rare lack of storage detoxification of accumulated metal. We thus propose a theoretical framework that can be extended to other metals and other aquatic invertebrates (indeed other animals) to explain the variation in the relationship between bioaccumulated body concentrations and toxicity, and subsequently to predict this relationship in many other species for which we have bioaccumulation modelling data.

  18. Challenges in using the ToxRefDB as a resource for toxicity prediction modeling.

    PubMed

    Plunkett, Laura M; Kaplan, A Michael; Becker, Richard A

    2015-08-01

    Developing and evaluating toxicity prediction models requires selection and use of datasets of known positive and negative agents for the endpoint(s) of interest. EPA's Toxicity Reference Database (ToxRefDB) is a publicly available dataset containing detailed study and effect information on more than 400 chemicals, and it has been used by EPA researchers to develop toxicity prediction models. During an initial evaluation of reproductive toxicity, however, limitations were uncovered in applying data from ToxRefDB that involved interpretation of toxicity effects and designation of toxicity endpoints, core attributes of the database that are critical to its use. These limitations for reproductive toxicity were found to be related, at least in part, to challenges faced in (1) evaluating the source of the original study data (EPA Data Evaluation Records (DERs)) for input into ToxRefDB and (2) interpretation of the biological significance of responses. These limitations of the ToxRefDB have important implications for the wider use of the database as it currently exists. Our results point to a need for improvements to the existing ToxRefDB and/or for researchers to independently evaluate, assign and verify positive or negative designations to data from ToxRefDB before use in development or validation of prediction models or testing frameworks.

  19. Metal and proton toxicity to lake zooplankton: a chemical speciation based modelling approach.

    PubMed

    Stockdale, Anthony; Tipping, Edward; Lofts, Stephen; Fott, Jan; Garmo, Oyvind A; Hruska, Jakub; Keller, Bill; Löfgren, Stefan; Maberly, Stephen C; Majer, Vladimir; Nierzwicki-Bauer, Sandra A; Persson, Gunnar; Schartau, Ann-Kristin; Thackeray, Stephen J; Valois, Amanda; Vrba, Jaroslav; Walseng, Bjørn; Yan, Norman

    2014-03-01

    The WHAM-FTOX model quantifies the combined toxic effects of protons and metal cations towards aquatic organisms through the toxicity function (FTOX), a linear combination of the products of organism-bound cation and a toxic potency coefficient for each cation. We describe the application of the model to predict an observable ecological field variable, species richness of pelagic lake crustacean zooplankton, studied with respect to either acidification or the impacts of metals from smelters. The fitted results give toxic potencies increasing in the order H(+) < Al < Cu < Zn < Ni. In general, observed species richness is lower than predicted, but in some instances agreement is close, and is rarely higher than predictions. The model predicts recovery in agreement with observations for three regions, namely Sudbury (Canada), Bohemian Forest (Czech Republic) and a subset of lakes across Norway, but fails to predict observed recovery from acidification in Adirondack lakes (USA).

  20. Predicting aquatic toxicities of chemical pesticides in multiple test species using nonlinear QSTR modeling approaches.

    PubMed

    Basant, Nikita; Gupta, Shikha; Singh, Kunwar P

    2015-11-01

    In this study, we established nonlinear quantitative-structure toxicity relationship (QSTR) models for predicting the toxicities of chemical pesticides in multiple aquatic test species following the OECD (Organization for Economic Cooperation and Development) guidelines. The decision tree forest (DTF) and decision tree boost (DTB) based QSTR models were constructed using a pesticides toxicity dataset in Selenastrum capricornutum and a set of six descriptors. Other six toxicity data sets were used for external validation of the constructed QSTRs. Global QSTR models were also constructed using the combined dataset of all the seven species. The diversity in chemical structures and nonlinearity in the data were evaluated. Model validation was performed deriving several statistical coefficients for the test data and the prediction and generalization abilities of the QSTRs were evaluated. Both the QSTR models identified WPSA1 (weighted charged partial positive surface area) as the most influential descriptor. The DTF and DTB QSTRs performed relatively better than the single decision tree (SDT) and support vector machines (SVM) models used as a benchmark here and yielded R(2) of 0.886 and 0.964 between the measured and predicted toxicity values in the complete dataset (S. capricornutum). The QSTR models applied to six other aquatic species toxicity data yielded R(2) of >0.92 (DTF) and >0.97 (DTB), respectively. The prediction accuracies of the global models were comparable with those of the S. capricornutum models. The results suggest for the appropriateness of the developed QSTR models to reliably predict the aquatic toxicity of chemicals and can be used for regulatory purpose.

  1. Meteorological and air pollution modeling for an urban airport

    NASA Technical Reports Server (NTRS)

    Swan, P. R.; Lee, I. Y.

    1980-01-01

    Results are presented of numerical experiments modeling meteorology, multiple pollutant sources, and nonlinear photochemical reactions for the case of an airport in a large urban area with complex terrain. A planetary boundary-layer model which predicts the mixing depth and generates wind, moisture, and temperature fields was used; it utilizes only surface and synoptic boundary conditions as input data. A version of the Hecht-Seinfeld-Dodge chemical kinetics model is integrated with a new, rapid numerical technique; both the San Francisco Bay Area Air Quality Management District source inventory and the San Jose Airport aircraft inventory are utilized. The air quality model results are presented in contour plots; the combined results illustrate that the highly nonlinear interactions which are present require that the chemistry and meteorology be considered simultaneously to make a valid assessment of the effects of individual sources on regional air quality.

  2. Modeling green infrastructure land use changes on future air ...

    EPA Pesticide Factsheets

    Green infrastructure can be a cost-effective approach for reducing stormwater runoff and improving water quality as a result, but it could also bring co-benefits for air quality: less impervious surfaces and more vegetation can decrease the urban heat island effect, and also result in more removal of air pollutants via dry deposition with increased vegetative surfaces. Cooler surface temperatures can also decrease ozone formation through the increases of NOx titration; however, cooler surface temperatures also lower the height of the boundary layer resulting in more concentrated pollutants within the same volume of air, especially for primary emitted pollutants (e.g. NOx, CO, primary particulate matter). To better understand how green infrastructure impacts air quality, the interactions between all of these processes must be considered collectively. In this study, we use a comprehensive coupled meteorology-air quality model (WRF-CMAQ) to simulate the influence of planned land use changes that include green infrastructure in Kansas City (KC) on regional meteorology and air quality. Current and future land use data was provided by the Mid-America Regional Council for 2012 and 2040 (projected land use due to population growth, city planning and green infrastructure implementation). These land use datasets were incorporated into the WRF-CMAQ modeling system allowing the modeling system to propagate the changes in vegetation and impervious surface coverage on meteoro

  3. Controlling VOC and air toxic emissions from aircraft refinishing facilities -- A new approach

    SciTech Connect

    Ayer, J.

    1997-12-31

    Preliminary studies conducted by the EPA and Air Force indicate that significant cost reductions are achievable by reducing booth exhaust flow rates via recirculation. Based on these results, the EPA and the US Marine Corps launched a full scale demonstration program in which several paint booths were modified at the Barstow MCLB to encompass recirculation and other ventilation system optimization strategies. Additionally, the booth exhaust streams were vented to an innovative VOC emission control device that has extremely low operating costs. The paper describes this full-scale demonstration program in which booth exhaust flow rates were safely reduced from 143,000 cfm to 44,000 cfm. This program (completed in September, 1996) encompassed several innovative elements, including: Permanent installation of split-flow/recirculation ventilation in 3 high production paint booths. Use of Variable Frequency Drive Fans to continually reduce booth flow rates to the lowest level while maintaining compliance with OSHA mandates. Integration of an innovative monitoring system using Fourier Transform Infrared (FTIR) to continuously monitor/speciate organic compound concentrations in recirculation ducts and ensure safe system operation. Installation of an ambient temperature emission control system that oxidizes the exhaust stream VOCs and is capable of instantaneous startup/shutdown operations; this is ideal for the Barstow MCLB high production operation. The ventilation systems were tested extensively to ensure a safe and efficient working environment; these test results indicate that recirculation and other system modifications successfully reduced flow rates to achieve low cost emission control. Results of a detailed economic analysis are also presented which demonstrate that ventilation system modification costs are quickly recovered from the installation/operation of a smaller VOC emission control device.

  4. Sodium toxicity in methanogenic systems: Rates and modeling

    SciTech Connect

    Yerkes, D.W.; Speece, R.E.

    1998-07-01

    In this paper, the mechanisms of sodium toxicity in methane producing anaerobic wastewater treatment systems are explored. Kinetic parameters for acetate uptake and sodium inhibition are determined. Methanosarcina enrichment cultures were used to determine a sodium inhibition constant, K{sub i}, of 295 mM. Methanosarcina showed complete acclimation to 500 mM Na{sup +} within 120 days. It is demonstrated that anaerobic systems have the ability to adapt over several weeks to very high concentrations of sodium, although the rate of methane production is slowed dramatically.

  5. MOAtox: A comprehensive mode of action and acute aquatic toxicity database for predictive model development (SETAC abstract)

    EPA Science Inventory

    The mode of toxic action (MOA) has been recognized as a key determinant of chemical toxicity and as an alternative to chemical class-based predictive toxicity modeling. However, the development of quantitative structure activity relationship (QSAR) and other models has been limit...

  6. A Bayesian network model for predicting aquatic toxicity mode of action using two dimensional theoretical molecular descriptors

    EPA Science Inventory

    The mode of toxic action (MoA) has been recognized as a key determinant of chemical toxicity, but development of predictive MoA classification models in aquatic toxicology has been limited. We developed a Bayesian network model to classify aquatic toxicity MoA using a recently pu...

  7. QSAR models for predicting in vivo aquatic toxicity of chlorinated alkanes to fish.

    PubMed

    Zvinavashe, Elton; van den Berg, Hans; Soffers, Ans E M F; Vervoort, Jacques; Freidig, Andreas; Murk, Albertinka J; Rietjens, Ivonne M C M

    2008-03-01

    Quantitative structure-activity relationship (QSAR) models are expected to play a crucial role in reducing the number of animals to be used for toxicity testing resulting from the adoption of the new European Union chemical control system called Registration, Evaluation, and Authorization of Chemicals (REACH). The objective of the present study was to generate in vitro acute toxicity data that could be used to develop a QSAR model to describe acute in vivo toxicity of chlorinated alkanes. Cytotoxicity of a series of chlorinated alkanes to Chinese hamster ovary (CHO) cells was observed at concentrations similar to those that have been shown previously to be toxic to fish. Strong correlations exist between the acute in vitro toxicity of the chlorinated alkanes and (i) hydrophobicity [modeled by the calculated log K ow (octanol-water partition coefficient); r (2) = 0.883 and r int (2) = 0.854] and (ii) in vivo acute toxicity to fish ( r (2) = 0.758). A QSAR model has been developed to predict in vivo acute toxicity to fish, based on the in vitro data and even on in silico log K ow data only. The developed QSAR model is applicable to chlorinated alkanes with up to 10 carbon atoms, up to eight chlorine atoms, and log K ow values lying within the range from 1.71 to 5.70. Out of the 100204 compounds on the European Inventory of Existing Chemicals (EINECS), our QSAR model covers 77 (0.1%) of them. Our findings demonstrate that in vitro experiments and even in silico calculations can replace animal experiments in the prediction of the acute toxicity of chlorinated alkanes.

  8. Four-dimensional evaluation of regional air quality models

    EPA Science Inventory

    We present highlights of the results obtained in the third phase of the Air Quality Model Evaluation International Initiative (AQMEII3). Activities in AQMEII3 were focused on evaluating the performance of global, hemispheric and regional modeling systems over Europe and North Ame...

  9. Modeling Trends in Air Pollutant Concentrations over the ...

    EPA Pesticide Factsheets

    Regional model calculations over annual cycles have pointed to the need for accurately representing impacts of long-range transport. Linking regional and global scale models have met with mixed success as biases in the global model can propagate and influence regional calculations and often confound interpretation of model results. Since transport is efficient in the free-troposphere and since simulations over Continental scales and annual cycles provide sufficient opportunity for “atmospheric turn-over”, i.e., exchange between the free-troposphere and the boundary-layer, a conceptual framework is needed wherein interactions between processes occurring at various spatial and temporal scales can be consistently examined. The coupled WRF-CMAQ model is expanded to hemispheric scales and model simulations over period spanning 1990-current are analyzed to examine changes in hemispheric air pollution resulting from changes in emissions over this period. The National Exposure Research Laboratory (NERL) Atmospheric Modeling and Analysis Division (AMAD) conducts research in support of EPA mission to protect human health and the environment. AMAD research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMAD is responsible for pr

  10. Real-Time Cell-Electronic Sensing of Coal Fly Ash Particulate Matter for Toxicity-Based Air Quality Monitoring.

    PubMed

    Moe, Birget; Yuan, Chungang; Li, Jinhua; Du, Haiying; Gabos, Stephan; Le, X Chris; Li, Xing-Fang

    2016-06-20

    The development of a unique bioassay for cytotoxicity analysis of coal fly ash (CFA) particulate matter (PM) and its potential application for air quality monitoring is described. Using human cell lines, A549 and SK-MES-1, as live probes on microelectrode-embedded 96-well sensors, impedance changes over time are measured as cells are treated with varying concentrations (1 μg/mL-20 mg/mL) of CFA samples. A dose-dependent impedance change is determined for each CFA sample, from which an IC50 histogram is obtained. The assay was successfully applied to examine CFA samples collected from three coal-fired power plants (CFPs) in China. The samples were separated into three size fractions: PM2.5 (<2.5 μm), PM10-2.5 (2.5 μm < x < 10 μm), and PM10 (>10 μm). Dynamic cell-response profiles and temporal IC50 histograms of all samples show that CFA cytotoxicity depends on concentration, exposure time (0-60 h), and cell-type (SK-MES-1 > A549). The IC50 values differentiate the cytotoxicity of CFA samples based on size fraction (PM2.5 ≈ PM10-2.5 ≫ PM10) and the sampling location (CFP2 > CFP1 ≈ CFP3). Differential cytotoxicity measurements of particulates in human cell lines using cell-electronic sensing provide a useful tool for toxicity-based air quality monitoring and risk assessment.

  11. An Evaluation of the Air-to-Air Engagement Models in the Naval Warfare Gaming System.

    DTIC Science & Technology

    1984-03-01

    RECCMMENDATIOVS AND CONCLUSIONS . . . . . . . . 120 A. ~MODEL EVALUATION CONCLUSIONS ........ 120 1. Approach to Air-tc- Ai : Engagement Modeling...T: ai i.%9 GrouDs located in Dar, Nack, Vig91-ia an! Sa=n Dago, c=lfri ==Z schsdulal to havs a st-and al,== ::;’r cn- hilifty hy FY87. !he Naval...ars: usre Or 13 faml.:E of models, use of data based modeling and a~: ai contrcl of forcqs. A family of models Is a Eat of modals ir !4,:: imc madal IS

  12. A new model for predicting time course toxicity of heavy metals based on Biotic Ligand Model (BLM).

    PubMed

    Hatano, Ayumi; Shoji, Ryo

    2010-01-01

    A new model for predicting time course toxicity of heavy metals was developed by extending the effective ratio of biotic ligand binding with toxic heavy metals to the total biotic ligand for 50% of test organisms (f(50)) derived by the Biotic Ligand Model (BLM). BLM has been well-known as a useful model for prediction of heavy metal toxicity. BLM can consider the effect of exposure conditions such as pH and Ca(2+) on heavy metal toxicity. In addition to the exposure conditions, heavy metal toxicity is strongly dependent on exposure time. In this study, BLM is extended to predict time dependency of heavy metal toxicity by connecting with the concept of primary reaction. The model developed in this study also generates the estimation of the 50% effect concentration (EC(50)) for toxicologically unknown organisms and heavy metals. Two toxicological and kinetic constants, f(50,0) and k, were derived from the initial value of f(50) (f(50,0)) and a time constant (k) independent of time. The model developed in this study enables us to acquire information on the toxicity of heavy metals such as Cu, Cd and Co easily.

  13. Estimating the Potential Toxicity of Chemicals Associated with Hydraulic Fracturing Operations Using Quantitative Structure-Activity Relationship Modeling

    EPA Pesticide Factsheets

    Researchers facilitated evaluation of chemicals that lack chronic oral toxicity values using a QSAR model to develop estimates of potential toxicity for chemicals used in HF fluids or found in flowback or produced water

  14. Air Quality Modeling of Traffic-related Air Pollutants for the NEXUS Study

    EPA Science Inventory

    The paper presents the results of the model applications to estimate exposure metrics in support of an epidemiologic study in Detroit, Michigan. A major challenge in traffic-related air pollution exposure studies is the lack of information regarding pollutant exposure characteriz...

  15. Steady-state computer design model for air-to-air heat pumps

    NASA Astrophysics Data System (ADS)

    Fischer, S. K.; Rice, C. K.

    1981-12-01

    A FORTRAN-4 computer program to predict the steady-state performance of conventional, vapor compression, electrically-driven, air-to-air heat pumps in both heating and cooling modes is described. This model is intended to serve as an analytical design tool for use by heat pump manufacturers, consulting engineers, research institutions, and universities in studies directed toward the improvement of heat pump performance. The heat pump design model allows the user to specify: system operating conditions, compressor characteristics, refrigerant flow control devices, fin-and-tube heat exchanger parameters, fan and indoor duct characteristics, and any of ten refrigerants. The model will compute: system capacity and COP (or EER), compressor and fan motor power consumptions, coil outlet air dry- and wet-bulb temperatures, air- and refrigerant-side pressure drops, a summary of the refrigerant-side states throughout the cycle, and overall compressor efficiencies and heat exchanger effectiveness. Documentation of how to use and/or modify the model is provided.

  16. Gene expression patterns in Rainbow Trout, Oncorhynchus mykiss, exposed to a suite of model toxicants

    SciTech Connect

    Hook, Sharon E.; Skillman, Ann D.; Small, Jonathan A.; Schultz, Irv R.

    2006-05-25

    The increased availability and use of DNA microarrays has allowed the characterization of gene expression patterns associated with different toxicants. An important question is whether toxicant induced changes in gene expression in fish are sufficiently diverse to allow for identification of specific modes of action and/or specific contaminants. In theory, each class of toxicant may generate a gene expression profile unique to its mode of toxic action. We exposed isogenic (cloned) rainbow trout Oncorhyncus mykiss, to sublethal levels of a series of model toxicants with varying modes of action, including ethynylestradiol (xeno-estrogen), trenbolone (anabolic steroid; model androgen), 2,2,4,4´tetrabromodiphenyl ether (BDE-47, thyroid active), diquat (oxidant stressor), chromium VI, and benzo[a]pyrene (BaP) for a period of 1-3 weeks. Following exposure, fish were euthanized, livers harvested and RNA extracted. Fluorescently labeled cDNA were generated and hybridized against a commercially available Atlantic Salmon / Trout array (GRASP project, University of Victoria) spotted with 16,000 cDNA’s. The slides were scanned to measure abundance of a given transcript in each sample relative to controls. Data were analyzed via Genespring (Silicon Genetics) to identify a list of up and down regulated genes, as well as to determine gene clustering patterns that can be used as “expression signatures”. Our analysis indicates each toxicant generated specific gene expression profiles. Most genes exhibiting altered expression responded to only one of the toxicants. Relatively few genes are co-expressed in multiple treatments. For example, BaP and Diquat, both of which exert toxicity via oxidative stress, up-regulated 28 of the same genes, of over 100 genes altered by ether treatment. Other genes associated with steroidogenesis, p450 and estrogen responsive genes appear to be useful for selectively identifying toxicant mode of in fish, suggesting a link between gene expression

  17. Gene expression patterns in rainbow trout, Oncorhynchus mykiss, exposed to a suite of model toxicants.

    PubMed

    Hook, Sharon E; Skillman, Ann D; Small, Jack A; Schultz, Irvin R

    2006-05-25

    The increased availability and use of DNA microarrays has allowed the characterization of gene expression patterns associated with exposure to different toxicants. An important question is whether toxicant induced changes in gene expression in fish are sufficiently diverse to allow for identification of specific modes of action and/or specific contaminants. In theory, each class of toxicant may generate a gene expression profile unique to its mode of toxic action. In this study, isogenic (cloned) rainbow trout Oncorhynchus mykiss were exposed to sublethal levels of a series of model toxicants with varying modes of action, including ethynylestradiol (xeno-estrogen), 2,2,4,4'-tetrabromodiphenyl ether (BDE-47, thyroid active), diquat (oxidant stressor), chromium VI, and benzo[a]pyrene (BaP) for a period of 1-3 weeks. An additional experiment measured trenbolone (anabolic steroid; model androgen) induced gene expression changes in sexually mature female trout. Following exposure, fish were euthanized, livers removed and RNA extracted. Fluorescently labeled cDNA were generated and hybridized against a commercially available Atlantic Salmon/Trout array (GRASP project, University of Victoria) spotted with 16,000 cDNA's. The slides were scanned to measure abundance of a given transcript in each sample relative to controls. Data were analyzed via Genespring (Silicon Genetics) to identify a list of up- and downregulated genes, as well as to determine gene clustering patterns that can be used as "expression signatures". The results indicate each toxicant exposure caused between 64 and 222 genes to be significantly altered in expression. Most genes exhibiting altered expression responded to only one of the toxicants and relatively few were co-expressed in multiple treatments. For example, BaP and Diquat, both of which exert toxicity via oxidative stress, upregulated 28 of the same genes, of over 100 genes altered by either treatment. Other genes associated with steroidogenesis

  18. Using biodynamic models to reconcile differences between laboratory toxicity tests and field biomonitoring with aquatic insects

    USGS Publications Warehouse

    Buchwalter, D.B.; Cain, D.J.; Clements, W.H.; Luoma, S.N.

    2007-01-01

    Aquatic insects often dominate lotic ecosystems, yet these organisms are under-represented in trace metal toxicity databases. Furthermore, toxicity data for aquatic insects do not appear to reflect their actual sensitivities to metals in nature, because the concentrations required to elicit toxicity in the laboratory are considerably higher than those found to impact insect communities in the field. New approaches are therefore needed to better understand how and why insects are differentially susceptible to metal exposures. Biodynamic modeling is a powerful tool for understanding interspecific differences in trace metal bioaccumulation. Because bioaccumulation alone does not necessarily correlate with toxicity, we combined biokinetic parameters associated with dissolved cadmium exposures with studies of the subcellular compartmentalization of accumulated Cd. This combination of physiological traits allowed us to make predictions of susceptibility differences to dissolved Cd in three aquatic insect taxa: Ephemerella excrucians, Rhithrogena morrisoni, and Rhyacophila sp. We compared these predictions with long-term field monitoring data and toxicity tests with closely related taxa: Ephemerella infrequens, Rhithrogena hageni, and Rhyacophila brunea. Kinetic parameters allowed us to estimate steady-state concentrations, the time required to reach steady state, and the concentrations of Cd projected to be in potentially toxic compartments for different species. Species-specific physiological traits identified using biodynamic models provided a means for better understanding why toxicity assays with insects have failed to provide meaningful estimates for metal concentrations that would be expected to be protective in nature. ?? 2007 American Chemical Society.

  19. Air Mass Considerations in Fog Optical Modeling.

    DTIC Science & Technology

    1981-02-01

    military forces are increasingly relying on new sophis - ticated weapons systems which employ electro-optical (EO) sensors or systems in their principles of...infrared extinction coefficients. Several authors (Stewart,10 Turner et all’) have shown that models which depend upon visibility alone can lead to...Extinction by Fog, TR-77-9, Technology Laboratory, Physical Science Directorate, Redstone Arsenal, AL 11R. E. Turner et al, 1978, Model Development for E-O

  20. Prediction of organ toxicity endpoints by QSAR modeling based on precise chemical-histopathology annotations.

    PubMed

    Myshkin, Eugene; Brennan, Richard; Khasanova, Tatiana; Sitnik, Tatiana; Serebriyskaya, Tatiana; Litvinova, Elena; Guryanov, Alexey; Nikolsky, Yuri; Nikolskaya, Tatiana; Bureeva, Svetlana

    2012-09-01

    The ability to accurately predict the toxicity of drug candidates from their chemical structure is critical for guiding experimental drug discovery toward safer medicines. Under the guidance of the MetaTox consortium (Thomson Reuters, CA, USA), which comprised toxicologists from the pharmaceutical industry and government agencies, we created a comprehensive ontology of toxic pathologies for 19 organs, classifying pathology terms by pathology type and functional organ substructure. By manual annotation of full-text research articles, the ontology was populated with chemical compounds causing specific histopathologies. Annotated compound-toxicity associations defined histologically from rat and mouse experiments were used to build quantitative structure-activity relationship models predicting subcategories of liver and kidney toxicity: liver necrosis, liver relative weight gain, liver lipid accumulation, nephron injury, kidney relative weight gain, and kidney necrosis. All models were validated using two independent test sets and demonstrated overall good performance: initial validation showed 0.80-0.96 sensitivity (correctly predicted toxic compounds) and 0.85-1.00 specificity (correctly predicted non-toxic compounds). Later validation against a test set of compounds newly added to the database in the 2 years following initial model generation showed 75-87% sensitivity and 60-78% specificity. General hepatotoxicity and nephrotoxicity models were less accurate, as expected for more complex endpoints.

  1. QSAR models for reproductive toxicity and endocrine disruption in regulatory use – a preliminary investigation†

    PubMed Central

    Jensen, G.E.; Niemelä, J.R.; Wedebye, E.B.; Nikolov, N.G.

    2008-01-01

    A special challenge in the new European Union chemicals legislation, Registration, Evaluation and Authorisation of Chemicals, will be the toxicological evaluation of chemicals for reproductive toxicity. Use of valid quantitative structure–activity relationships (QSARs) is a possibility under the new legislation. This article focuses on a screening exercise by use of our own and commercial QSAR models for identification of possible reproductive toxicants. Three QSAR models were used for reproductive toxicity for the endpoints teratogenic risk to humans (based on animal tests, clinical data and epidemiological human studies), dominant lethal effect in rodents (in vivo) and Drosophila melanogaster sex-linked recessive lethal effect. A structure set of 57,014 European Inventory of Existing Chemical Substances (EINECS) chemicals was screened. A total of 5240 EINECS chemicals, corresponding to 9.2%, were predicted as reproductive toxicants by one or more of the models. The chemicals predicted positive for reproductive toxicity will be submitted to the Danish Environmental Protection Agency as scientific input for a future updated advisory classification list with advisory classifications for concern for humans owing to possible developmental toxic effects: Xn (Harmful) and R63 (Possible risk of harm to the unborn child). The chemicals were also screened in three models for endocrine disruption. PMID:19061080

  2. Mathematical model of an air-filled alpha stirling refrigerator

    NASA Astrophysics Data System (ADS)

    McFarlane, Patrick; Semperlotti, Fabio; Sen, Mihir

    2013-10-01

    This work develops a mathematical model for an alpha Stirling refrigerator with air as the working fluid and will be useful in optimizing the mechanical design of these machines. Two pistons cyclically compress and expand air while moving sinusoidally in separate chambers connected by a regenerator, thus creating a temperature difference across the system. A complete non-linear mathematical model of the machine, including air thermodynamics, and heat transfer from the walls, as well as heat transfer and fluid resistance in the regenerator, is developed. Non-dimensional groups are derived, and the mathematical model is numerically solved. The heat transfer and work are found for both chambers, and the coefficient of performance of each chamber is calculated. Important design parameters are varied and their effect on refrigerator performance determined. This sensitivity analysis, which shows what the significant parameters are, is a useful tool for the design of practical Stirling refrigeration systems.

  3. Lung toxicity determination by in vitro exposure at the air liquid interface with an integrated online dose measurement

    NASA Astrophysics Data System (ADS)

    Mülhopt, Sonja; Diabaté, S.; Krebs, T.; Weiss, C.; Paur, H.-R.

    2009-05-01

    Epidemiological studies show an association between the concentration of ultrafine particles in the atmosphere and the rate of mortality or morbidity due to respiratory and cardiovascular diseases. For the quantitative assessment of the toxicity of airborne nanoparticles the dose-response relationship is tested in in vitro test systems using bioassays of cell cultures as sensor. For the air-liquid interface exposure of cell cultures towards aerosols the Karlsruhe exposure system was developed. The human lung cell cultures are exposed in VITROCELL® system modules with a constant flow of the conditioned aerosol. After exposure the cells are analyzed to measure the biological responses such as viability, inflammatory or oxidative stress. For the determination of the dose response relationship the accurate knowledge of the deposited particle mass is essential. A new online method is developed in the Karlsruhe exposure system: the sensor of a quartz crystal microbalance is placed in an exposure chamber instead of the membrane insert and exposed to the aerosol in the same way as the cell cultures. The deposited mass per area unit is monitored as a function of exposure time showing a linear relationship for a constant aerosol flow with defined particle concentration. A comparison of this new dose signal to a dosimetry method using fluorescein sodium particles shows a very good correlation between the sensor signal of the quartz crystal microbalance and the deposited mass on the membranes shown by spectroscopy. This system for the first time provides an online dose measurement for in vitro experiments with nanoparticles.

  4. Modelling the risk of airborne infectious disease using exhaled air.

    PubMed

    Issarow, Chacha M; Mulder, Nicola; Wood, Robin

    2015-05-07

    In this paper we develop and demonstrate a flexible mathematical model that predicts the risk of airborne infectious diseases, such as tuberculosis under steady state and non-steady state conditions by monitoring exhaled air by infectors in a confined space. In the development of this model, we used the rebreathed air accumulation rate concept to directly determine the average volume fraction of exhaled air in a given space. From a biological point of view, exhaled air by infectors contains airborne infectious particles that cause airborne infectious diseases such as tuberculosis in confined spaces. Since not all infectious particles can reach the target infection site, we took into account that the infectious particles that commence the infection are determined by respiratory deposition fraction, which is the probability of each infectious particle reaching the target infection site of the respiratory tracts and causing infection. Furthermore, we compute the quantity of carbon dioxide as a marker of exhaled air, which can be inhaled in the room with high likelihood of causing airborne infectious disease given the presence of infectors. We demonstrated mathematically and schematically the correlation between TB transmission probability and airborne infectious particle generation rate, ventilation rate, average volume fraction of exhaled air, TB prevalence and duration of exposure to infectors in a confined space.

  5. Joint space-time geostatistical model for air quality surveillance

    NASA Astrophysics Data System (ADS)

    Russo, A.; Soares, A.; Pereira, M. J.

    2009-04-01

    Air pollution and peoples' generalized concern about air quality are, nowadays, considered to be a global problem. Although the introduction of rigid air pollution regulations has reduced pollution from industry and power stations, the growing number of cars on the road poses a new pollution problem. Considering the characteristics of the atmospheric circulation and also the residence times of certain pollutants in the atmosphere, a generalized and growing interest on air quality issues led to research intensification and publication of several articles with quite different levels of scientific depth. As most natural phenomena, air quality can be seen as a space-time process, where space-time relationships have usually quite different characteristics and levels of uncertainty. As a result, the simultaneous integration of space and time is not an easy task to perform. This problem is overcome by a variety of methodologies. The use of stochastic models and neural networks to characterize space-time dispersion of air quality is becoming a common practice. The main objective of this work is to produce an air quality model which allows forecasting critical concentration episodes of a certain pollutant by means of a hybrid approach, based on the combined use of neural network models and stochastic simulations. A stochastic simulation of the spatial component with a space-time trend model is proposed to characterize critical situations, taking into account data from the past and a space-time trend from the recent past. To identify near future critical episodes, predicted values from neural networks are used at each monitoring station. In this paper, we describe the design of a hybrid forecasting tool for ambient NO2 concentrations in Lisbon, Portugal.

  6. Acute Toxicity Prediction to Threatened and Endangered Species Using Interspecies Correlation Estimation (ICE) Models.

    PubMed

    Willming, Morgan M; Lilavois, Crystal R; Barron, Mace G; Raimondo, Sandy

    2016-10-04

    Evaluating contaminant sensitivity of threatened and endangered (listed) species and protectiveness of chemical regulations often depends on toxicity data for commonly tested surrogate species. The U.S. EPA's Internet application Web-ICE is a suite of Interspecies Correlation Estimation (ICE) models that can extrapolate species sensitivity to listed taxa using least-squares regressions of the sensitivity of a surrogate species and a predicted taxon (species, genus, or family). Web-ICE was expanded with new models that can predict toxicity to over 250 listed species. A case study was used to assess protectiveness of genus and family model estimates derived from either geometric mean or minimum taxa toxicity values for listed species. Models developed from the most sensitive value for each chemical were generally protective of the most sensitive species within predicted taxa, including listed species, and were more protective than geometric means models. ICE model estimates were compared to HC5 values derived from Species Sensitivity Distributions for the case study chemicals to assess protectiveness of the two approaches. ICE models provide robust toxicity predictions and can generate protective toxicity estimates for assessing contaminant risk to listed species.

  7. Nanoparticle toxicity assessment using an in vitro 3-D kidney organoid culture model.

    PubMed

    Astashkina, Anna I; Jones, Clint F; Thiagarajan, Giridhar; Kurtzeborn, Kristen; Ghandehari, Hamid; Brooks, Benjamin D; Grainger, David W

    2014-08-01

    Nanocarriers and nanoparticles remain an intense pharmaceutical and medical imaging technology interest. Their entry into clinical use is hampered by the lack of reliable in vitro models that accurately predict in vivo toxicity. This study evaluates a 3-D kidney organoid proximal tubule culture to assess in vitro toxicity of the hydroxylated generation-5 PAMAM dendrimer (G5-OH) compared to previously published preclinical in vivo rodent nephrotoxicity data. 3-D kidney proximal tubule cultures were created using isolated murine proximal tubule fractions suspended in a biomedical grade hyaluronic acid-based hydrogel. Toxicity in these cultures to neutral G5-OH dendrimer nanoparticles and gold nanoparticles in vitro was assessed using clinical biomarker generation. Neutral PAMAM nanoparticle dendrimers elicit in vivo-relevant kidney biomarkers and cell viability in a 3-D kidney organoid culture that closely reflect toxicity markers reported in vivo in rodent nephrotoxicity models exposed to this same nanoparticle.

  8. Modeling urban air pollution with optimized hierarchical fuzzy inference system.

    PubMed

    Tashayo, Behnam; Alimohammadi, Abbas

    2016-10-01

    Environmental exposure assessments (EEA) and epidemiological studies require urban air pollution models with appropriate spatial and temporal resolutions. Uncertain available data and inflexible models can limit air pollution modeling techniques, particularly in under developing countries. This paper develops a hierarchical fuzzy inference system (HFIS) to model air pollution under different land use, transportation, and meteorological conditions. To improve performance, the system treats the issue as a large-scale and high-dimensional problem and develops the proposed model using a three-step approach. In the first step, a geospatial information system (GIS) and probabilistic methods are used to preprocess the data. In the second step, a hierarchical structure is generated based on the problem. In the third step, the accuracy and complexity of the model are simultaneously optimized with a multiple objective particle swarm optimization (MOPSO) algorithm. We examine the capabilities of the proposed model for predicting daily and annual mean PM2.5 and NO2 and compare the accuracy of the results with representative models from existing literature. The benefits provided by the model features, including probabilistic preprocessing, multi-objective optimization, and hierarchical structure, are precisely evaluated by comparing five different consecutive models in terms of accuracy and complexity criteria. Fivefold cross validation is used to assess the performance of the generated models. The respective average RMSEs and coefficients of determination (R (2)) for the test datasets using proposed model are as follows: daily PM2.5 = (8.13, 0.78), annual mean PM2.5 = (4.96, 0.80), daily NO2 = (5.63, 0.79), and annual mean NO2 = (2.89, 0.83). The obtained results demonstrate that the developed hierarchical fuzzy inference system can be utilized for modeling air pollution in EEA and epidemiological studies.

  9. Per- and polyfluoro toxicity (LC(50) inhalation) study in rat and mouse using QSAR modeling.

    PubMed

    Bhhatarai, Barun; Gramatica, Paola

    2010-03-15

    Fully or partially fluorinated compounds, known as per- and polyfluorinated chemicals are widely distributed in the environment and released because of their use in different household and industrial products. Few of these long chain per- and polyfluorinated chemicals are classified as emerging pollutants, and their environmental and toxicological effects are unveiled in the literature. This has diverted the production of long chain compounds, considered as more toxic, to short chains, but concerns regarding the toxicity of both types of per- and polyfluorinated chemicals are alarming. There are few experimental data available on the environmental behavior and toxicity of these compounds, and moreover, toxicity profiles are found to be different for the types of animals and species used. Quantitative structure-activity relationship (QSAR) is applied to a combination of short and long chain per- and polyfluorinated chemicals, for the first time, to model and predict the toxicity on two species of rodents, rat (Rattus) and mouse (Mus), by modeling inhalation (LC(50)) data. Multiple linear regression (MLR) models using the ordinary-least-squares (OLS) method, based on theoretical molecular descriptors selected by genetic algorithm (GA), were used for QSAR studies. Training and prediction sets were prepared a priori, and these sets were used to derive statistically robust and predictive (both internally and externally) models. The structural applicability domain (AD) of the model was verified on a larger set of per- and polyfluorinated chemicals retrieved from different databases and journals. The descriptors involved, the similarities, and the differences observed between models pertaining to the toxicity related to the two species are discussed. Chemometric methods such as principal component analysis (PCA) and multidimensional scaling (MDS) were used to select most toxic compounds from those within the AD of both models, which will be subjected to experimental tests

  10. CFD Modeling For Urban Air Quality Studies

    SciTech Connect

    Lee, R L; Lucas, L J; Humphreys, T D; Chan, S T

    2003-10-27

    The computational fluid dynamics (CFD) approach has been increasingly applied to many atmospheric applications, including flow over buildings and complex terrain, and dispersion of hazardous releases. However there has been much less activity on the coupling of CFD with atmospheric chemistry. Most of the atmospheric chemistry applications have been focused on the modeling of chemistry on larger spatial scales, such as global or urban airshed scale. However, the increased attentions to terrorism threats have stimulated the need of much more detailed simulations involving chemical releases within urban areas. This motivated us to develop a new CFD/coupled-chemistry capability as part of our modeling effort.

  11. Modeling the Environmental Impact of Air Traffic Operations

    NASA Technical Reports Server (NTRS)

    Chen, Neil

    2011-01-01

    There is increased interest to understand and mitigate the impacts of air traffic on the climate, since greenhouse gases, nitrogen oxides, and contrails generated by air traffic can have adverse impacts on the climate. The models described in this presentation are useful for quantifying these impacts and for studying alternative environmentally aware operational concepts. These models have been developed by leveraging and building upon existing simulation and optimization techniques developed for the design of efficient traffic flow management strategies. Specific enhancements to the existing simulation and optimization techniques include new models that simulate aircraft fuel flow, emissions and contrails. To ensure that these new models are beneficial to the larger climate research community, the outputs of these new models are compatible with existing global climate modeling tools like the FAA's Aviation Environmental Design Tool.

  12. Modeling of membrane processes for air revitalization and water recovery

    NASA Technical Reports Server (NTRS)

    Lange, Kevin E.; Foerg, Sandra L.; Dall-Bauman, Liese A.

    1992-01-01

    Gas-separation and reverse-osmosis membrane models are being developed in conjunction with membrane testing at NASA JSC. The completed gas-separation membrane model extracts effective component permeabilities from multicomponent test data, and predicts the effects of flow configuration, operating conditions, and membrane dimensions on module performance. Variable feed- and permeate-side pressures are considered. The model has been applied to test data for hollow-fiber membrane modules with simulated cabin-air feeds. Results are presented for a membrane designed for air drying applications. Extracted permeabilities are used to predict the effect of operating conditions on water enrichment in the permeate. A first-order reverse-osmosis model has been applied to test data for spiral wound membrane modules with a simulated hygiene water feed. The model estimates an effective local component rejection coefficient under pseudosteady-state conditions. Results are used to define requirements for a detailed reverse-osmosis model.

  13. Mathematical model of one-man air revitalization system

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A mathematical model was developed for simulating the steady state performance in electrochemical CO2 concentrators which utilize (NMe4)2 CO3 (aq.) electrolyte. This electrolyte, which accommodates a wide range of air relative humidity, is most suitable for one-man air revitalization systems. The model is based on the solution of coupled nonlinear ordinary differential equations derived from mass transport and rate equations for the processes which take place in the cell. The boundary conditions are obtained by solving the mass and energy transport equations. A shooting method is used to solve the differential equations.

  14. Computer Model Simulates Air Pollution Over Roads

    ERIC Educational Resources Information Center

    Environmental Science and Technology, 1972

    1972-01-01

    A sophisticated modeling technique which predicts pollutant movement accurately and may aid in the design of new freeways is reported. EXPLOR (Examination of Pollution Levels of Roadways) was developed specifically to predict pollutant concentrations in a milewide corridor traversed by a roadway. (BL)

  15. Multispecies QSAR modeling for predicting the aquatic toxicity of diverse organic chemicals for regulatory toxicology.

    PubMed

    Singh, Kunwar P; Gupta, Shikha; Kumar, Anuj; Mohan, Dinesh

    2014-05-19

    The research aims to develop multispecies quantitative structure-activity relationships (QSARs) modeling tools capable of predicting the acute toxicity of diverse chemicals in various Organization for Economic Co-operation and Development (OECD) recommended test species of different trophic levels for regulatory toxicology. Accordingly, the ensemble learning (EL) approach based classification and regression QSAR models, such as decision treeboost (DTB) and decision tree forest (DTF) implementing stochastic gradient boosting and bagging algorithms were developed using the algae (P. subcapitata) experimental toxicity data for chemicals. The EL-QSAR models were successfully applied to predict toxicities of wide groups of chemicals in other test species including algae (S. obliguue), daphnia, fish, and bacteria. Structural diversity of the selected chemicals and those of the end-point toxicity data of five different test species were tested using the Tanimoto similarity index and Kruskal-Wallis (K-W) statistics. Predictive and generalization abilities of the constructed QSAR models were compared using statistical parameters. The developed QSAR models (DTB and DTF) yielded a considerably high classification accuracy in complete data of model building (algae) species (97.82%, 99.01%) and ranged between 92.50%-94.26% and 92.14%-94.12% in four test species, respectively, whereas regression QSAR models (DTB and DTF) rendered high correlation (R(2)) between the measured and model predicted toxicity end-point values and low mean-squared error in model building (algae) species (0.918, 0.15; 0.905, 0.21) and ranged between 0.575 and 0.672, 0.18-0.51 and 0.605-0.689 and 0.20-0.45 in four different test species. The developed QSAR models exhibited good predictive and generalization abilities in different test species of varied trophic levels and can be used for predicting the toxicities of new chemicals for screening and prioritization of chemicals for regulation.

  16. Meteorological Processes Affecting Air Quality – Research and Model Development Needs

    EPA Science Inventory

    Meteorology modeling is an important component of air quality modeling systems that defines the physical and dynamical environment for atmospheric chemistry. The meteorology models used for air quality applications are based on numerical weather prediction models that were devel...

  17. Air Dispersion Modeling for the INL Application for a Synthetic Minor Sitewide Air Quality Permit to Construct with a Facility Emission Cap Component

    SciTech Connect

    Sondrup, Andrus Jeffrey

    2015-10-01

    The Department of Energy Idaho Operations Office (DOE-ID) is applying for a synthetic minor, Sitewide, air quality permit to construct (PTC) with a facility emission cap (FEC) component from the Idaho Department of Environmental Quality (DEQ) for Idaho National Laboratory (INL) to limit its potential to emit to less than major facility limits for criteria air pollutants (CAPs) and hazardous air pollutants (HAPs) regulated under the Clean Air Act. This document is supplied as an appendix to the application, Idaho National Laboratory Application for a Synthetic Minor Sitewide Air Quality Permit to Construct with a Facility Emissions Cap Component, hereafter referred to as “permit application” (DOE-ID 2015). Air dispersion modeling was performed as part of the permit application process to demonstrate pollutant emissions from the INL will not cause a violation of any ambient air quality standards. This report documents the modeling methodology and results for the air dispersion impact analysis. All CAPs regulated under Section 109 of the Clean Air Act were modeled with the exception of lead (Pb) and ozone, which are not required to be modeled by DEQ. Modeling was not performed for toxic air pollutants (TAPs) as uncontrolled emissions did not exceed screening emission levels for carcinogenic and non-carcinogenic TAPs. Modeling for CAPs was performed with the EPA approved AERMOD dispersion modeling system (Version 14134) (EPA 2004a) and five years (2000-2004) of meteorological data. The meteorological data set was produced with the companion AERMET model (Version 14134) (EPA 2004b) using surface data from the Idaho Falls airport, and upper-air data from Boise International Airport supplied by DEQ. Onsite meteorological data from the Grid 3 Mesonet tower located near the center of the INL (north of INTEC) and supplied by the local National Oceanic and Atmospheric Administration (NOAA) office was used for surface wind directions and wind speeds. Surface data (i

  18. Air injection test on a Kaplan turbine: prototype - model comparison

    NASA Astrophysics Data System (ADS)

    Angulo, M.; Rivetti, A.; Díaz, L.; Liscia, S.

    2016-11-01

    Air injection is a very well-known resource to reduce pressure pulsation magnitude in turbines, especially on Francis type. In the case of large Kaplan designs, even when not so usual, it could be a solution to mitigate vibrations arising when tip vortex cavitation phenomenon becomes erosive and induces structural vibrations. In order to study this alternative, aeration tests were performed on a Kaplan turbine at model and prototype scales. The research was focused on efficiency of different air flow rates injected in reducing vibrations, especially at the draft tube and the discharge ring and also in the efficiency drop magnitude. It was found that results on both scales presents the same trend in particular for vibration levels at the discharge ring. The efficiency drop was overestimated on model tests while on prototype were less than 0.2 % for all power output. On prototype, air has a beneficial effect in reducing pressure fluctuations up to 0.2 ‰ of air flow rate. On model high speed image computing helped to quantify the volume of tip vortex cavitation that is strongly correlated with the vibration level. The hydrophone measurements did not capture the cavitation intensity when air is injected, however on prototype, it was detected by a sonometer installed at the draft tube access gallery.

  19. A Predictive Model for Toxicity Effects Assessment of Biotransformed Hepatic Drugs Using Iterative Sampling Method

    PubMed Central

    Tharwat, Alaa; Moemen, Yasmine S.; Hassanien, Aboul Ella

    2016-01-01

    Measuring toxicity is one of the main steps in drug development. Hence, there is a high demand for computational models to predict the toxicity effects of the potential drugs. In this study, we used a dataset, which consists of four toxicity effects:mutagenic, tumorigenic, irritant and reproductive effects. The proposed model consists of three phases. In the first phase, rough set-based methods are used to select the most discriminative features for reducing the classification time and improving the classification performance. Due to the imbalanced class distribution, in the second phase, different sampling methods such as Random Under-Sampling, Random Over-Sampling and Synthetic Minority Oversampling Technique are used to solve the problem of imbalanced datasets. ITerative Sampling (ITS) method is proposed to avoid the limitations of those methods. ITS method has two steps. The first step (sampling step) iteratively modifies the prior distribution of the minority and majority classes. In the second step, a data cleaning method is used to remove the overlapping that is produced from the first step. In the third phase, Bagging classifier is used to classify an unknown drug into toxic or non-toxic. The experimental results proved that the proposed model performed well in classifying the unknown samples according to all toxic effects in the imbalanced datasets. PMID:27934950

  20. Modelling of radio emission from cosmic ray air showers

    NASA Astrophysics Data System (ADS)

    Ludwig, Marianne

    2011-06-01

    Cosmic rays entering the Earth's atmosphere induce extensive air showers consisting of up to billions of secondary particles. Among them, a multitude of electrons and positrons are generated. These get deflected in the Earth's magnetic field, creating time-varying transverse currents. Thereby, the air shower emits coherent radiation in the MHz frequency range measured by radio antenna arrays on the ground such as LOPES at the KIT. This detection method provides a possibility to study cosmic rays with energies above 1017 eV. At this time, the radio technique undergoes the change from prototype experiments to large scale application. Thus, a detailed understanding of the radio emission process is needed more than ever. Before starting this work, different models made conflicting predictions on the pulse shape and the amplitude of the radio signal. It turned out that a radiation component caused by the variation of the number of charged particles within the air shower was missed in several models. The Monte Carlo code REAS2 superposing the radiation of the individual air shower electrons and positrons was one of those. At this time, it was not known how to take the missing component into account. For REAS3, we developed and implemented the endpoint formalism, a universal approach, to calculate the radiation from each single particle. For the first time, we achieve a good agreement between REAS3 and MGMR, an independent and completely different simulation approach. In contrast to REAS3, MGMR is based on a macroscopic approach and on parametrisations of the air shower. We studied the differences in the underlying air shower models to explain the remaining deviations. For comparisons with LOPES data, we developed a new method which allows "top-down" simulations of air showers. From this, we developed an air shower selection criterion based on the number of muons measured with KASCADE to take shower-to-shower fluctuations for a single event analysis into account. With

  1. Validation of Air Traffic Controller Workload Models

    DTIC Science & Technology

    1979-09-01

    SAR) tapes dtirinq the data reduc- tion phase of the project. Kentron International Limited provided the software support for the oroject. This included... ETABS ) or to revised traffic control procedures. The models also can be used to verify productivity benefits after new configurations have been...col- lected and processed manually. A preliminary compari- son has been made between standard NAS Stage A and ETABS operations at Miami. 1.2

  2. Neural Network Models of Air Combat Maneuvering

    DTIC Science & Technology

    1992-07-01

    great dcl of research has been conducted on the perceptual- motor skills of fighter plane pilots, the cognitive and decision-making skills have received...relatively little attention. A better understanding of cognitive skills can make important contributions to pilot training and to various aspects of...performance assessment. In previous work, we have collected data and developed models relating to pilots’ cognitive structures and to the selection of

  3. Mathematical Model of an Air Cushion Vehicle

    DTIC Science & Technology

    1975-05-01

    otion, cushion dynamics, control and machinery dynamics and water wave effects are mwdeled. DD IJ එ 1473 EOITION OF I NOV 6 IS OBSOLETE U...cushion pressure model, the calculations are based on scanty experimental and analytical evidence that should not be taken for more than what it is...updates are readily incorporated. Many of the forces acting on the vehicle are curve fits to experimental4data obtained by Bell Aerospace and used in their

  4. Likelihood of achieving air quality targets under model uncertainties.

    PubMed

    Digar, Antara; Cohan, Daniel S; Cox, Dennis D; Kim, Byeong-Uk; Boylan, James W

    2011-01-01

    Regulatory attainment demonstrations in the United States typically apply a bright-line test to predict whether a control strategy is sufficient to attain an air quality standard. Photochemical models are the best tools available to project future pollutant levels and are a critical part of regulatory attainment demonstrations. However, because photochemical models are uncertain and future meteorology is unknowable, future pollutant levels cannot be predicted perfectly and attainment cannot be guaranteed. This paper introduces a computationally efficient methodology for estimating the likelihood that an emission control strategy will achieve an air quality objective in light of uncertainties in photochemical model input parameters (e.g., uncertain emission and reaction rates, deposition velocities, and boundary conditions). The method incorporates Monte Carlo simulations of a reduced form model representing pollutant-precursor response under parametric uncertainty to probabilistically predict the improvement in air quality due to emission control. The method is applied to recent 8-h ozone attainment modeling for Atlanta, Georgia, to assess the likelihood that additional controls would achieve fixed (well-defined) or flexible (due to meteorological variability and uncertain emission trends) targets of air pollution reduction. The results show that in certain instances ranking of the predicted effectiveness of control strategies may differ between probabilistic and deterministic analyses.

  5. 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.

  6. Hazardous Air Pollutants

    MedlinePlus

    ... Air Toxics Website Rules and Implementation Related Information Air Quality Data and Tools Clean Air Act Criteria Air ... Resources Visibility and Haze Voluntary Programs for Improving Air Quality Contact Us to ask a question, provide feedback, ...

  7. Modelled air pollution levels versus EC air quality legislation - results from high resolution simulation.

    PubMed

    Chervenkov, Hristo

    2013-12-01

    An appropriate method for evaluating the air quality of a certain area is to contrast the actual air pollution levels to the critical ones, prescribed in the legislative standards. The application of numerical simulation models for assessing the real air quality status is allowed by the legislation of the European Community (EC). This approach is preferable, especially when the area of interest is relatively big and/or the network of measurement stations is sparse, and the available observational data are scarce, respectively. Such method is very efficient for similar assessment studies due to continuous spatio-temporal coverage of the obtained results. In the study the values of the concentration of the harmful substances sulphur dioxide, (SO2), nitrogen dioxide (NO2), particulate matter - coarse (PM10) and fine (PM2.5) fraction, ozone (O3), carbon monoxide (CO) and ammonia (NH3) in the surface layer obtained from modelling simulations with resolution 10 km on hourly bases are taken to calculate the necessary statistical quantities which are used for comparison with the corresponding critical levels, prescribed in the EC directives. For part of them (PM2.5, CO and NH3) this is done for first time with such resolution. The computational grid covers Bulgaria entirely and some surrounding territories and the calculations are made for every year in the period 1991-2000. The averaged over the whole time slice results can be treated as representative for the air quality situation of the last decade of the former century.

  8. Economic damages of ozone air pollution to crops using combined air quality and GIS modelling

    NASA Astrophysics Data System (ADS)

    Vlachokostas, Ch.; Nastis, S. A.; Achillas, Ch.; Kalogeropoulos, K.; Karmiris, I.; Moussiopoulos, N.; Chourdakis, E.; Banias, G.; Limperi, N.

    2010-09-01

    This study aims at presenting a combined air quality and GIS modelling methodological approach in order to estimate crop damages from photochemical air pollution, depict their spatial resolution and assess the order of magnitude regarding the corresponding economic damages. The analysis is conducted within the Greater Thessaloniki Area, Greece, a Mediterranean territory which is characterised by high levels of photochemical air pollution and considerable agricultural activity. Ozone concentration fields for 2002 and for specific emission reduction scenarios for the year 2010 were estimated with the Ozone Fine Structure model in the area under consideration. Total economic damage to crops turns out to be significant and estimated to be approximately 43 M€ for the reference year. Production of cotton presents the highest economic loss, which is over 16 M€, followed by table tomato (9 M€), rice (4.2 M€), wheat (4 M€) and oilseed rape (2.8 M€) cultivations. Losses are not spread uniformly among farmers and the major losses occur in areas with valuable ozone-sensitive crops. The results are very useful for highlighting the magnitude of the total economic impacts of photochemical air pollution to the area's agricultural sector and can potentially be used for comparison with studies worldwide. Furthermore, spatial analysis of the economic damage could be of importance for governmental authorities and decision makers since it provides an indicative insight, especially if the economic instruments such as financial incentives or state subsidies to farmers are considered.

  9. European Air Quality and Climate Change: a numerical modeling study

    NASA Astrophysics Data System (ADS)

    Lacressonniere, G.

    2011-12-01

    In the context of climate change, the evolution of air quality in Europe is a challenging scientific question, despite the political measures taken to limit and reduce anthropogenic emissions. Heat waves, changes in transport pathways or synoptic patterns, increase of emissions in other areas in the world, or for instance possible increase of biogenic emissions or changes in deposition and land use may affect adversely future Air Quality levels in Europe. In the context of a project co-funded by the French environment agency ADEME, a numerical modeling study has begun relying on the tools used by Météo-France for its contribution to the 5th IPCC assessment report, to GMES atmospheric services (MACC FP7 project) and to the French national operational Air Quality platform Prév'Air (http://www.prevair.org). In particular, the MOCAGE 3-D chemical transport model (CTM) is used with a configuration comprising a global (2°) and a European domain (0.2°), allowing representation of both long-range transport of pollutants and European Air Quality at relevant resolutions and with a two-ways coupling. MOCAGE includes 47 layers from the surface to 5hPa. The first step of this project was to assess the impact of meteorological forcings, either analyses ("best" meteorology available for the recent past) or climate runs for the current atmosphere, on air quality hindcasts with MOCAGE over Europe. For these climate runs, we rely on Météo-France Earth-System model CNRM-CM, and particularly the ARPEGE-climate general circulation model for the atmosphere. By studying several key variables for Air Quality (surface and low troposphere concentrations of ozone, nitrogen oxides, volatile organic compounds, radicals, PM,...), we investigated the indicators that are robust, through averages over several years, (monthly averages, frequency of exceedances, AOTs, ...) for a given climate when using climatological forcings instead of analyses, which constitutes the reference. Both

  10. Ecotoxicity interspecies QAAR models from Daphnia toxicity of pharmaceuticals and personal care products.

    PubMed

    Sangion, A; Gramatica, P

    2016-10-01

    Pharmaceutical and Personal Care Products (PPCPs) became a class of contaminants of emerging concern because are ubiquitously detected in surface water and soil, where they can affect wildlife. Ecotoxicological data are only available for a few PPCPs, thus modelling approaches are essential tools to maximize the information contained in the existing data. In silico methods may be helpful in filling data gaps for the toxicity of PPCPs towards various ecological indicator organisms. The good correlation between toxicity toward Daphnia magna and those on two fish species (Pimephales promelas and Oncorhynchus mykiss), improved by the addition of one theoretical molecular descriptor, allowed us to develop predictive models to investigate the relationship between toxicities in different species. The aim of this work is to propose quantitative activity-activity relationship (QAAR) models, developed in QSARINS and validated for their external predictivity. Such models can be used to predict the toxicity of PPCPs to a particular species using available experimental toxicity data from a different species, thus reducing the tests on organisms of higher trophic level. Similarly, good QAAR models, implemented by molecular descriptors to improve the quality, are proposed here for fish interspecies. We also comment on the relevance of autocorrelation descriptors in improving all studied interspecies correlations.

  11. A Near-Road Modeling System for Community-Scale Assessments of Traffic-Related AirPollution in the United States

    EPA Science Inventory

    The Community Line Source (C-LINE) modeling system estimates emissions and dispersion of toxic air pollutants for roadways within the continental United States. It accesses publicly available traffic and meteorological datasets, and is optimized for use on community-sized areas (...

  12. A Zebrafish Model for Uremic Toxicity: Role of the Complement Pathway

    PubMed Central

    Thurman, Josh; Reinecke, James; Raff, Amanda C.; Melamed, Michal L.; Reinecke, James; Quan, Zhe; Evans, Todd; Meyer, Timothy W.; Hostetter, Thomas H

    2016-01-01

    Many organic solutes accumulate in ESRD and some are poorly removed removed with urea based prescriptions for hemodialysis. However, their toxicities have been difficult to assess. We have employed an animal model, the zebrafish embryo, to test the toxicity of uremic serum compared to control. Serum was obtained from stable ESRD patients pre-dialysis or from normal subjects. Zebrafish embryos 24 hours post fertilization were exposed to experimental media at a ratio of 3:1 water:human serum. Those exposed to serum from uremic subjects had significantly reduced survival at 8 hours (19% +/− 18% vs. 94% +/− 6%; p < 0.05, uremic serum vs control, respectively). Embryos exposed to serum from ESRD subjects fractionated at 50kD showed significantly greater toxicity with the larger molecular weight fraction (83% +/− 11% vs 7% +/−17% survival, p < 0.05, <50kD vs >50 kD, respectively). Heating serum abrogated its toxicity. EDTA, a potent inhibitor of complement by virtue of calcium chelation, reduced the toxicity of uremic serum compared to untreated uremic serum (96%+/− 5% vs 28%+/− 20% survival, p < 0.016, chelated vs non chelated serum respectively). Anti- factor B, a specific inhibitor of the alternative complement pathway, reduced the toxicity of uremic serum, compared to untreated uremic serum (98% +/− 6% vs. 3% +/− 9% survival, p < 0.016, anti- factor B treated vs non treated, respectively).Uremic serum is thus more toxic to zebrafish embryos than normal serum. Furthermore, this toxicity is associated with a fraction of large size, is inactivated by heat, and is reduced by both specific and non-specific inhibitors of complement activation. Together these data lend support to the hypothesis that at least some uremic toxicities may be mediated by complement. PMID:23689420

  13. A zebrafish model for uremic toxicity: role of the complement pathway.

    PubMed

    Berman, Nathaniel; Lectura, Melisa; Thurman, Joshua M; Reinecke, James; Raff, Amanda C; Melamed, Michal L; Quan, Zhe; Evans, Todd; Meyer, Timothy W; Hostetter, Thomas H

    2013-01-01

    Many organic solutes accumulate in end-stage renal disease (ESRD) and some are poorly removed with urea-based prescriptions for hemodialysis. However, their toxicities have been difficult to assess. We have employed an animal model, the zebrafish embryo, to test the toxicity of uremic serum compared to control. Serum was obtained from stable ESRD patients predialysis or from normal subjects. Zebrafish embryos 24 h postfertilization were exposed to experimental media at a water:human serum ratio of 3:1. Those exposed to serum from uremic subjects had significantly reduced survival at 8 h (19 ± 18 vs. 94 ± 6%, p < 0.05, uremic serum vs. control, respectively). Embryos exposed to serum from ESRD subjects fractionated at 50 kDa showed significantly greater toxicity with the larger molecular weight fraction (83 ± 11 vs. 7 ± 17% survival, p < 0.05, <50 vs. >50 kDa, respectively). Heating serum abrogated its toxicity. EDTA, a potent inhibitor of complement by virtue of calcium chelation, reduced the toxicity of uremic serum compared to untreated uremic serum (96 ± 5 vs. 28 ± 20% survival, p < 0.016, chelated vs. nonchelated serum, respectively). Anti-factor B, a specific inhibitor of the alternative complement pathway, reduced the toxicity of uremic serum, compared to untreated uremic serum (98 ± 6 vs. 3 ± 9% survival, p < 0.016, anti-factor B treated vs. nontreated, respectively). Uremic serum is thus more toxic to zebrafish embryos than normal serum. Furthermore, this toxicity is associated with a fraction of large size, is inactivated by heat, and is reduced by both specific and nonspecific inhibitors of complement activation. Together these data lend support to the hypothesis that at least some uremic toxicities may be mediated by complement.

  14. Modifications to toxic CUG RNAs induce structural stability, rescue mis-splicing in a myotonic dystrophy cell model and reduce toxicity in a myotonic dystrophy zebrafish model

    DOE PAGES

    deLorimier, Elaine; Coonrod, Leslie A.; Copperman, Jeremy; ...

    2014-10-10

    In this study, CUG repeat expansions in the 3' UTR of dystrophia myotonica protein kinase (DMPK) cause myotonic dystrophy type 1 (DM1). As RNA, these repeats elicit toxicity by sequestering splicing proteins, such as MBNL1, into protein–RNA aggregates. Structural studies demonstrate that CUG repeats can form A-form helices, suggesting that repeat secondary structure could be important in pathogenicity. To evaluate this hypothesis, we utilized structure-stabilizing RNA modifications pseudouridine (Ψ) and 2'-O-methylation to determine if stabilization of CUG helical conformations affected toxicity. CUG repeats modified with Ψ or 2'-O-methyl groups exhibited enhanced structural stability and reduced affinity for MBNL1. Molecular dynamicsmore » and X-ray crystallography suggest a potential water-bridging mechanism for Ψ-mediated CUG repeat stabilization. Ψ modification of CUG repeats rescued mis-splicing in a DM1 cell model and prevented CUG repeat toxicity in zebrafish embryos. This study indicates that the structure of toxic RNAs has a significant role in controlling the onset of neuromuscular diseases.« less

  15. Modifications to toxic CUG RNAs induce structural stability, rescue mis-splicing in a myotonic dystrophy cell model and reduce toxicity in a myotonic dystrophy zebrafish model

    SciTech Connect

    deLorimier, Elaine; Coonrod, Leslie A.; Copperman, Jeremy; Taber, Alex; Reister, Emily E.; Sharma, Kush; Todd, Peter K.; Guenza, Marina G.; Berglund, J. Andrew

    2014-10-10

    In this study, CUG repeat expansions in the 3' UTR of dystrophia myotonica protein kinase (DMPK) cause myotonic dystrophy type 1 (DM1). As RNA, these repeats elicit toxicity by sequestering splicing proteins, such as MBNL1, into protein–RNA aggregates. Structural studies demonstrate that CUG repeats can form A-form helices, suggesting that repeat secondary structure could be important in pathogenicity. To evaluate this hypothesis, we utilized structure-stabilizing RNA modifications pseudouridine (Ψ) and 2'-O-methylation to determine if stabilization of CUG helical conformations affected toxicity. CUG repeats modified with Ψ or 2'-O-methyl groups exhibited enhanced structural stability and reduced affinity for MBNL1. Molecular dynamics and X-ray crystallography suggest a potential water-bridging mechanism for Ψ-mediated CUG repeat stabilization. Ψ modification of CUG repeats rescued mis-splicing in a DM1 cell model and prevented CUG repeat toxicity in zebrafish embryos. This study indicates that the structure of toxic RNAs has a significant role in controlling the onset of neuromuscular diseases.

  16. Modeling, Monitoring and Fault Diagnosis of Spacecraft Air Contaminants

    NASA Technical Reports Server (NTRS)

    Ramirez, W. Fred; Skliar, Mikhail; Narayan, Anand; Morgenthaler, George W.; Smith, Gerald J.

    1998-01-01

    Control of air contaminants is a crucial factor in the safety considerations of crewed space flight. Indoor air quality needs to be closely monitored during long range missions such as a Mars mission, and also on large complex space structures such as the International Space Station. This work mainly pertains to the detection and simulation of air contaminants in the space station, though much of the work is easily extended to buildings, and issues of ventilation systems. Here we propose a method with which to track the presence of contaminants using an accurate physical model, and also develop a robust procedure that would raise alarms when certain tolerance levels are exceeded. A part of this research concerns the modeling of air flow inside a spacecraft, and the consequent dispersal pattern of contaminants. Our objective is to also monitor the contaminants on-line, so we develop a state estimation procedure that makes use of the measurements from a sensor system and determines an optimal estimate of the contamination in the system as a function of time and space. The real-time optimal estimates in turn are used to detect faults in the system and also offer diagnoses as to their sources. This work is concerned with the monitoring of air contaminants aboard future generation spacecraft and seeks to satisfy NASA's requirements as outlined in their Strategic Plan document (Technology Development Requirements, 1996).

  17. Ecotoxicogenomic approaches for understanding molecular mechanisms of environmental chemical toxicity using aquatic invertebrate, Daphnia model organism.

    PubMed

    Kim, Hyo Jeong; Koedrith, Preeyaporn; Seo, Young Rok

    2015-05-29

    Due to the rapid advent in genomics technologies and attention to ecological risk assessment, the term "ecotoxicogenomics" has recently emerged to describe integration of omics studies (i.e., transcriptomics, proteomics, metabolomics, and epigenomics) into ecotoxicological fields. Ecotoxicogenomics is defined as study of an entire set of genes or proteins expression in ecological organisms to provide insight on environmental toxicity, offering benefit in ecological risk assessment. Indeed, Daphnia is a model species to study aquatic environmental toxicity designated in the Organization for Economic Co-operation and Development's toxicity test guideline and to investigate expression patterns using ecotoxicology-oriented genomics tools. Our main purpose is to demonstrate the potential utility of gene expression profiling in ecotoxicology by identifying novel biomarkers and relevant modes of toxicity in Daphnia magna. These approaches enable us to address adverse phenotypic outcomes linked to particular gene function(s) and mechanistic understanding of aquatic ecotoxicology as well as exploration of useful biomarkers. Furthermore, key challenges that currently face aquatic ecotoxicology (e.g., predicting toxicant responses among a broad spectrum of phytogenetic groups, predicting impact of temporal exposure on toxicant responses) necessitate the parallel use of other model organisms, both aquatic and terrestrial. By investigating gene expression profiling in an environmentally important organism, this provides viable support for the utility of ecotoxicogenomics.

  18. Ecotoxicogenomic Approaches for Understanding Molecular Mechanisms of Environmental Chemical Toxicity Using Aquatic Invertebrate, Daphnia Model Organism

    PubMed Central

    Kim, Hyo Jeong; Koedrith, Preeyaporn; Seo, Young Rok

    2015-01-01

    Due to the rapid advent in genomics technologies and attention to ecological risk assessment, the term “ecotoxicogenomics” has recently emerged to describe integration of omics studies (i.e., transcriptomics, proteomics, metabolomics, and epigenomics) into ecotoxicological fields. Ecotoxicogenomics is defined as study of an entire set of genes or proteins expression in ecological organisms to provide insight on environmental toxicity, offering benefit in ecological risk assessment. Indeed, Daphnia is a model species to study aquatic environmental toxicity designated in the Organization for Economic Co-operation and Development’s toxicity test guideline and to investigate expression patterns using ecotoxicology-oriented genomics tools. Our main purpose is to demonstrate the potential utility of gene expression profiling in ecotoxicology by identifying novel biomarkers and relevant modes of toxicity in Daphnia magna. These approaches enable us to address adverse phenotypic outcomes linked to particular gene function(s) and mechanistic understanding of aquatic ecotoxicology as well as exploration of useful biomarkers. Furthermore, key challenges that currently face aquatic ecotoxicology (e.g., predicting toxicant responses among a broad spectrum of phytogenetic groups, predicting impact of temporal exposure on toxicant responses) necessitate the parallel use of other model organisms, both aquatic and terrestrial. By investigating gene expression profiling in an environmentally important organism, this provides viable support for the utility of ecotoxicogenomics. PMID:26035755

  19. A Bayesian network model for predicting aquatic toxicity mode of action using two dimensional theoretical molecular descriptors-abstract

    EPA Science Inventory

    The mode of toxic action (MoA) has been recognized as a key determinant of chemical toxicity but MoA classification in aquatic toxicology has been limited. We developed a Bayesian network model to classify aquatic toxicity mode of action using a recently published dataset contain...

  20. Scale Issues in Air Quality Modeling Policy Support

    EPA Science Inventory

    This study examines the issues relating to the use of regional photochemical air quality models for evaluating their performance in reproducing the spatio-temporal features embedded in the observations and for designing emission control strategies needed to achieve compliance wit...

  1. EPA RESEARCH HIGHLIGHTS -- MODELS-3/CMAQ OFFERS COMPREHENSIVE APPROACH TO AIR QUALITY MODELING

    EPA Science Inventory

    Regional and global coordinated efforts are needed to address air quality problems that are growing in complexity and scope. Models-3 CMAQ contains a community multi-scale air quality modeling system for simulating urban to regional scale pollution problems relating to troposphe...

  2. InMAP: a new model for air pollution interventions

    NASA Astrophysics Data System (ADS)

    Tessum, C. W.; Hill, J. D.; Marshall, J. D.

    2015-10-01

    Mechanistic air pollution models are essential tools in air quality management. Widespread use of such models is hindered, however, by the extensive expertise or computational resources needed to run most models. Here, we present InMAP (Intervention Model for Air Pollution), which offers an alternative to comprehensive air quality models for estimating the air pollution health impacts of emission reductions and other potential interventions. InMAP estimates annual-average changes in primary and secondary fine particle (PM2.5) concentrations - the air pollution outcome generally causing the largest monetized health damages - attributable to annual changes in precursor emissions. InMAP leverages pre-processed physical and chemical information from the output of a state-of-the-science chemical transport model (WRF-Chem) within an Eulerian modeling framework, to perform simulations that are several orders of magnitude less computationally intensive than comprehensive model simulations. InMAP uses a variable resolution grid that focuses on human exposures by employing higher spatial resolution in urban areas and lower spatial resolution in rural and remote locations and in the upper atmosphere; and by directly calculating steady-state, annual average concentrations. In comparisons run here, InMAP recreates WRF-Chem predictions of changes in total PM2.5 concentrations with population-weighted mean fractional error (MFE) and bias (MFB) < 10 % and population-weighted R2 ~ 0.99. Among individual PM2.5 species, the best predictive performance is for primary PM2.5 (MFE: 16 %; MFB: 13 %) and the worst predictive performance is for particulate nitrate (MFE: 119 %; MFB: 106 %). Potential uses of InMAP include studying exposure, health, and environmental justice impacts of potential shifts in emissions for annual-average PM2.5. Features planned for future model releases include a larger spatial domain, more temporal information, and the ability to predict ground-level ozone (O3

  3. Predicting copper toxicity to different earthworm species using a multicomponent Freundlich model.

    PubMed

    Qiu, Hao; Vijver, Martina G; He, Erkai; Peijnenburg, Willie J G M

    2013-05-07

    This study aimed to develop bioavailability models for predicting Cu toxicity to earthworms (Lumbricus rubellus, Aporrectodea longa, and Eisenia fetida) in a range of soils of varying properties. A multicomponent Freundlich model, complying with the basic assumption of the biotic ligands model, was used to relate Cu toxicity to the free Cu(2+) activity and possible protective cations in soil porewater. Median lethal concentrations (LC50s) of Cu based on the total Cu concentration varied in each species from soil to soil, reaching differences of approximately a factor 9 in L. rubellus, 49 in A. longa and 45 in E. fetida. The relative sensitivity of the earthworms to Cu in different soils followed the same order: L. rubellus > A. longa > E. fetida. Only pH not other cations (K(+), Ca(2+), Na(+), and Mg(2+)) were found to exert significant protective effects against Cu toxicity to earthworms. The Freundlich-type model in which the protective effects of pH were included, explained 84%, 94%, and 96% of variations in LC50s of Cu (expressed as free ion activity) for L. rubellus, A. longa, and E. fetida, respectively. Predicted LC50s never differed by a factor of more than 2 from the observed LC50s. External validation of the model showed a similar level of precision, even though toxicity data for other soil organisms and for different endpoints were used. The findings of the present study showed the possibility of extrapolating the developed toxicity models for one earthworm species to another species. Moreover, the Freundlich-type model in which the free Cu(2+) activity and pH in soil porewater are considered can even be used to predict toxicity for other soil invertebrates and plants.

  4. Modeling air pollution in the Tracking and Analysis Framework (TAF)

    SciTech Connect

    Shannon, J.D.

    1998-12-31

    The Tracking and Analysis Framework (TAF) is a set of interactive computer models for integrated assessment of the Acid Rain Provisions (Title IV) of the 1990 Clean Air Act Amendments. TAF is designed to execute in minutes on a personal computer, thereby making it feasible for a researcher or policy analyst to examine quickly the effects of alternate modeling assumptions or policy scenarios. Because the development of TAF involves researchers in many different disciplines, TAF has been given a modular structure. In most cases, the modules contain reduced-form models that are based on more complete models exercised off-line. The structure of TAF as of December 1996 is shown. Both the Atmospheric Pathways Module produce estimates for regional air pollution variables.

  5. Toxicity of copper oxide nanoparticles in lung epithelial cells exposed at the air-liquid interface compared with in vivo assessment

    PubMed Central

    Jing, Xuefang; Park, Jae Hong; Peters, Thomas M.; Thorne, Peter S.

    2015-01-01

    The toxicity of spark-generated copper oxide nanoparticles (CuONPs) was evaluated in human bronchial epithelial cells (HBEC) and lung adenocarcinoma cells (A549 cells) using an in vitro air-liquid interface (ALI) exposure system. Dose-response results were compared to in vivo inhalation and instillation studies of CuONP. Cells were exposed to particle-free clean air (controls) or spark-generated CuONPs. The number median diameter, geometric standard deviation and total number concentration of CuONPs were 9.2 nm, 1.48 and 2.27×107 particles/cm3, respectively. Outcome measures included cell viability, cytotoxicity, oxidative stress and proinflammatory chemokine production. Exposure to clean air (2 or 4 hr) did not induce toxicity in HBEC or A549 cells. Compared with controls, CuONP exposures significantly reduced cell viability, increased lactate dehydrogenase (LDH) release and elevated levels of reactive oxygen species (ROS) and IL-8 in a dose-dependent manner. A549 cells were significantly more susceptible to CuONP effects than HBEC. Antioxidant treatment reduced CuONP-induced cytotoxicity. When dose was expressed per area of exposed epithelium there was good agreement of toxicity measures with murine in vivo studies. This demonstrates that in vitro ALI studies can provide meaningful data on nanotoxicity of metal oxides. PMID:25575782

  6. The reduction of gas phase air toxics from combustion and incineration sources using the GE-MITSUI-BE activated coke process

    SciTech Connect

    Olson, D.G.

    1995-12-31

    The dry desulfurization, denitrification and air toxics removal process using activated coke (AC) was originally researched and developed during the 1960s by Bergbau Forschung (BF), now called Deutsche Montan Technologies. Mitsui Mining Company (MMC) signed a licensing agreement with BF in 1982 to investigate, test and adapt the system to the facilities in Japan. Japanese regulations are stricter than in the U.S. toward SO{sub x}/NO{sub x} pollutants, as well as flyash emissions from the utility industry, oil refineries and other industries. This process is installed on flour coal-fired boilers and Fluidized Catalytic Cracker (FCC) units. These plants were constructed by MCC in Japan and Uhde GmbH in Germany. General Electric Environmental Systems, Inc. (GEESI) signed a license agreement in 1992 with MMC and Mitsui and Company, Ltd. of Tokyo. Under this agreement, GEESI will market, design, fabricate and install the Mitsui-BF press for flue gas cleaning applications in North America. MMC also developed a technology to produce AC used in the dry DeSO{sub x}/DeNO{sub x}/Air Toxics removal process based on their own metallurgical coke manufacturing technology. This paper provides information on the details of MMC`s AC used in the dry DeSO{sub x}/DeNO{sub x}/Air Toxics removal process.

  7. Developing Mental Models about Air Using Inquiry-Based Instruction with Kindergartners

    ERIC Educational Resources Information Center

    Van Hook, Stephen; Huziak, Tracy; Nowak, Katherine

    2005-01-01

    This study examines the development of mental models of air by kindergarten students after completing a series of hands-on, inquiry-based science lessons. The lessons focused on two properties of air: (1) that air takes up space and (2) that it is made of particles ("balls of air"). The students were interviewed about their ideas of air and about…

  8. The analysis of a generic air-to-air missile simulation model

    NASA Technical Reports Server (NTRS)

    Kaplan, Joseph A.; Chappell, Alan R.; Mcmanus, John W.

    1994-01-01

    A generic missile model was developed to evaluate the benefits of using a dynamic missile fly-out simulation system versus a static missile launch envelope system for air-to-air combat simulation. This paper examines the performance of a launch envelope model and a missile fly-out model. The launch envelope model bases its probability of killing the target aircraft on the target aircraft's position at the launch time of the weapon. The benefits gained from a launch envelope model are the simplicity of implementation and the minimal computational overhead required. A missile fly-out model takes into account the physical characteristics of the missile as it simulates the guidance, propulsion, and movement of the missile. The missile's probability of kill is based on the missile miss distance (or the minimum distance between the missile and the target aircraft). The problems associated with this method of modeling are a larger computational overhead, the additional complexity required to determine the missile miss distance, and the additional complexity of determining the reason(s) the missile missed the target. This paper evaluates the two methods and compares the results of running each method on a comprehensive set of test conditions.

  9. The Virtual Liver: Modeling Chemical-Induced Liver Toxicity

    EPA Science Inventory

    The US EPA Virtual Liver (v-Liver) project is aimed at modeling chemical-induced processes in hepatotoxicity and simulating their dose-dependent perturbations. The v-Liver embodies an emerging field of research in computational tissue modeling that integrates molecular and cellul...

  10. Curve fitting toxicity test data: Which comes first, the dose response or the model?

    SciTech Connect

    Gully, J.; Baird, R.; Bottomley, J.

    1995-12-31

    The probit model frequently does not fit the concentration-response curve of NPDES toxicity test data and non-parametric models must be used instead. The non-parametric models, trimmed Spearman-Karber, IC{sub p}, and linear interpolation, all require a monotonic concentration-response. Any deviation from a monotonic response is smoothed to obtain the desired concentration-response characteristics. Inaccurate point estimates may result from such procedures and can contribute to imprecision in replicate tests. The following study analyzed reference toxicant and effluent data from giant kelp (Macrocystis pyrifera), purple sea urchin (Strongylocentrotus purpuratus), red abalone (Haliotis rufescens), and fathead minnow (Pimephales promelas) bioassays using commercially available curve fitting software. The purpose was to search for alternative parametric models which would reduce the use of non-parametric models for point estimate analysis of toxicity data. Two non-linear models, power and logistic dose-response, were selected as possible alternatives to the probit model based upon their toxicological plausibility and ability to model most data sets examined. Unlike non-parametric procedures, these and all parametric models can be statistically evaluated for fit and significance. The use of the power or logistic dose response models increased the percentage of parametric model fits for each protocol and toxicant combination examined. The precision of the selected non-linear models was also compared with the EPA recommended point estimation models at several effect.levels. In general, precision of the alternative models was equal to or better than the traditional methods. Finally, use of the alternative models usually produced more plausible point estimates in data sets where the effects of smoothing and non-parametric modeling made the point estimate results suspect.

  11. Helicopter air resonance modeling and suppression using active control

    NASA Technical Reports Server (NTRS)

    Takahashi, M. D.; Friedmann, P. P.

    1991-01-01

    A coupled rotor/fuselage helicopter analysis with the important effects of blade torsional flexibility, unsteady aerodynamics, and forward flight is presented. Using this mathematical model, a nominal configuration is selected with an air resonance instability throughout most of its flight envelope. A multivariable compensator is then designed using two swashplate inputs and a single-body roll rate measurement. The controller design is based on the linear quadratic Gaussian technique and the loop transfer recovery method. The controller is shown to suppress the air resonance instability throughout a wide range of helicopter loading conditions and forward flight speeds.

  12. Controlling indoor air pollution from tobacco smoke: models and measurements

    SciTech Connect

    Offermann, F.J.; Girman, J.R.; Sextro, R.G.

    1984-07-01

    The effects of smoking rate, ventilation, surface deposition, and air cleaning on the indoor concentrations of respirable particulate matter and carbon monoxide generated by cigarette smoke are examined. A general mass balance model is presented which has been extended to include the concept of ventilation efficiency. Following a review of the source and removal terms associated with respirable particles and carbon monoxide, model predictions to various health guidelines are compared. 20 references, 1 figure.

  13. Air-water analogy and the study of hydraulic models

    NASA Technical Reports Server (NTRS)

    Supino, Giulio

    1953-01-01

    The author first sets forth some observations about the theory of models. Then he established certain general criteria for the construction of dynamically similar models in water and in air, through reference to the perfect fluid equations and to the ones pertaining to viscous flow. It is, in addition, pointed out that there are more cases in which the analogy is possible than is commonly supposed.

  14. Modeling of air pollution from the power plant ash dumps

    NASA Astrophysics Data System (ADS)

    Aleksic, Nenad M.; Balać, Nedeljko

    A simple model of air pollution from power plant ash dumps is presented, with emission rates calculated from the Bagnold formula and transport simulated by the ATDL type model. Moisture effects are accounted for by assumption that there is no pollution on rain days. Annual mean daily sedimentation rates, calculated for the area around the 'Nikola Tesla' power plants near Belgrade for 1987, show reasonably good agreement with observations.

  15. Air pollution dispersion models for human exposure predictions in London.

    PubMed

    Beevers, Sean D; Kitwiroon, Nutthida; Williams, Martin L; Kelly, Frank J; Ross Anderson, H; Carslaw, David C

    2013-01-01

    The London household survey has shown that people travel and are exposed to air pollutants differently. This argues for human exposure to be based upon space-time-activity data and spatio-temporal air quality predictions. For the latter, we have demonstrated the role that dispersion models can play by using two complimentary models, KCLurban, which gives source apportionment information, and Community Multi-scale Air Quality Model (CMAQ)-urban, which predicts hourly air quality. The KCLurban model is in close agreement with observations of NO(X), NO(2) and particulate matter (PM)(10/2.5), having a small normalised mean bias (-6% to 4%) and a large Index of Agreement (0.71-0.88). The temporal trends of NO(X) from the CMAQ-urban model are also in reasonable agreement with observations. Spatially, NO(2) predictions show that within 10's of metres of major roads, concentrations can range from approximately 10-20 p.p.b. up to 70 p.p.b. and that for PM(10/2.5) central London roadside concentrations are approximately double the suburban background concentrations. Exposure to different PM sources is important and we predict that brake wear-related PM(10) concentrations are approximately eight times greater near major roads than at suburban background locations. Temporally, we have shown that average NO(X) concentrations close to roads can range by a factor of approximately six between the early morning minimum and morning rush hour maximum periods. These results present strong arguments for the hybrid exposure model under development at King's and, in future, for in-building models and a model for the London Underground.

  16. Modeling exposure to air pollution from the WTC disaster based on reports of perceived air pollution.

    PubMed

    Lederman, Sally Ann; Becker, Mark; Sheets, Stephen; Stein, Janet; Tang, Deliang; Weiss, Lisa; Perera, Frederica P

    2008-04-01

    We examined the utility of a newly developed perceived air pollution (PAP) scale and of a modeled air pollution (MAP) scale derived from it for predicting previously observed birth outcomes of pregnant women enrolled following September 11, 2001. Women reported their home and work locations in the four weeks after September 11, 2001 and the PAP at each site on a four-point scale designed for this purpose. Locations were geocoded and their distance from the World Trade Center (WTC) site determined. PAP values were used to develop a model of air pollution for a 20-mile radius from the WTC site. MAP values were assigned to each geocoded location. We examined the relationship of PAP and MAP values to maternal characteristics and to distance of home and work sites from the WTC site. Both PAP and MAP values were highly correlated with distance from the WTC. Maternal characteristics that were associated with PAP values reported for home or work sites (race, demoralization, material hardship, first trimester on September 11) were not associated with modeled MAP values. Relationships of several birth outcomes to proximity to the WTC, which we previously reported using this data set, were also seen when MAP values were used as the measure of exposure, instead of proximity. MAP developed from reports of PAP may be useful to identify high-risk areas and predict health outcomes when there are multiple sources of pollution and a "distance from source" analysis is impossible.

  17. MODELS-3 COMMUNITY MULTISCALE AIR QUALITY (CMAQ) MODEL AEROSOL COMPONENT 1: MODEL DESCRIPTION

    EPA Science Inventory

    The aerosol component of the Community Multiscale Air Quality (CMAQ) model is designed to be an efficient and economical depiction of aerosol dynamics in the atmosphere. The approach taken represents the particle size distribution as the superposition of three lognormal subdis...

  18. An air quality modeling approach to satellite remote sensing

    NASA Astrophysics Data System (ADS)

    Yang, E.; Christopher, S. A.

    2012-12-01

    We simulate visible and near-infrared reflectance of the GOES-R Advanced Baseline Imager (ABI) for cases of high aerosol loading with haze and smoke over the eastern United States. The simulations are performed using the Weather Research and Forecasting (WRF), Sparse Matrix Operator Kernel Emissions (SMOKE), and Community Multiscale Air Quality (CMAQ) models to reproduce meteorological conditions, background emissions, and chemical transport of air pollutants. Geostationary satellite-derived biomass burning emissions are also included as an input to CMAQ to fully represent aerosol loadings. Radiance is computed from the discrete ordinate atmospheric radiative transfer model. We show that the model simulations create a realistic set of reflectance in various aerosol scenarios. The simulated reflectance provides distinct spectral features of aerosols during the simulated satellite scene acquisition, which is compared to and verified with the Moderate Resolution Imaging Spectroradiometer (MODIS) true-color imagery. We also present a simple technique to synthesize green band reflectance, which will not be available on GOES-R ABI, using the model-simulated blue and red band reflectance. The model-based spectral signatures provide a simple way to select relevant and to deselect irrelevant spectral information from multispectral data. This study is an example of the use of air quality modeling in improving products and techniques for Earth observing missions.

  19. Assessment of two-temperature kinetic model for ionizing air

    NASA Technical Reports Server (NTRS)

    Park, Chul

    1987-01-01

    A two-temperature chemical-kinetic model for air is assessed by comparing theoretical results with existing experimental data obtained in shock-tubes, ballistic ranges, and flight experiments. In the model, named the TTv model, one temperature (T) is assumed to characterize the heavy-particle translational and molecular rotational energies, and another temperature (Tv) to characterize the molecular vibrational, electron translational, and electronic excitation energies. The theoretical results for nonequilibrium air flow in shock tubes are obtained using the computer code STRAP (Shock-Tube Radiation Program), and for flow along the stagnation streamline in the shock layer over spherical bodies using the newly developed code STRAP (Stagnation-Point Radiation Program). Substantial agreement is shown between the theoretical and experimental results for relaxation times and radiative heat fluxes. At very high temperatures the spectral calculations need further improvement. The present agreement provides strong evidence that the two-temperature model characterizes principal features of nonequilibrium air flow. New theoretical results using the model are presented for the radiative heat fluxes at the stagnation point of a 6-m-radius sphere, representing an aeroassisted orbital transfer vehicle, over a range of free-stream conditions. Assumptions, approximations, and limitations of the model are discussed.

  20. Modeling toxicity due to intermittent exposure of rainbow trout and common shiners to monochloramine

    SciTech Connect

    Meyer, J.S.; Gulley, D.D. . Dept. of Zoology and Physiology); Goodrich, M.S. ); Szmania, D.C.; Brooks, A.S. . Center for Great Lakes Studies)

    1995-01-01

    The authors evaluated the ability of three mathematical models to predict toxicity to common shiners and rainbow trout during intermittent (pulsed) exposures to monochloramine, based on data from continuous-exposure toxicity tests. If a power term for the exposure-water concentration was included in the models, a concentration x time (Cxt) model and the Mancini uptake-depuration model predicted pulse LC50s to within [+-]50% of the observed pulse LC50s, for the first four pulses in toxicity tests with 2-h pulse/22-h recovery cycles. Beyond the fourth pulse cycle, though, the pulse LC50s predicted using the Cxt model appeared to diverge considerably from the trend of the experimental pulse LC50s, partly because this model does not predict an incipient lethal level (C[sub ILL]) for either continuous or intermittent exposures. The Mancini model predicted the C[sub ILL] moderately well in the common shiner intermittent-exposure test but not in the rainbow trout intermittent-exposure test. The Breck three-dimensional damage-repair model did not predict pulse LC50 or C[sub ILL] values as well as did the other two models, probably because not enough partial-mortality data were available to parameterize the model adequately. Although the underlying processes appear to be more complex than what these simple models assume, the models may still be adequate for use in regulating a few pulse discharges of monochloramine.