National Estimates of Outdoor Air Toxics Concentrations

Data from the Total Exposure Assessment Methodology studies, conducted from 1980 to 1987 in New Jersey ( NJ ) and California ( CA ) , and the 1990 California Indoor Exposure study were analyzed using positive matrix factorization, a receptor -oriented source apportionment model. Personal exposure and outdoor concentrations of 14 and 17 toxic volatile organic compounds ( VOCs ) were studied from the NJ and CA data, respectively. Analyzing both the personal exposure and outdoor concentrations made it possible to compare toxic VOCs in outdoor air and exposure resulting from personal activities. Regression analyses of the measured concentrations versus the factor scores were performed to determine the relative contribution of each factor to total exposure concentrations. Activity patterns of the NJ and CA participants were examined to determine whether reported exposures to specific sources correspond to higher estimated contributions from the factor identified with that source. For a subset of VOCs, a preliminary analysis to determine irritancybased contributions of factors to exposures was carried out. Major source types of toxic VOCs in both NJ and CA appear to be aromatic sources resembling automobile exhaust, gasoline vapor, or environmental tobacco smoke for personal exposures, and automobile exhaust or gasoline vapors for outdoor concentrations.

show abstract

“…This factor resembles background outdoor concentrations of these compounds ( Rosenbaum et al, 1999) .…”

Section: Anderson Et Almentioning

confidence: 92%

Source apportionment of exposure to toxic volatile organic compounds using positive matrix factorization

Anderson

Miller

Milford

2001

J Expo Sci Environ Epidemiol

View full text Add to dashboard Cite

show abstract

“…We obtained the Minnesota CEP modeling results from the U.S. EPA. The details of the CEP study are presented elsewhere (6)(7)(8)14). Briefly, 1990 emissions of 148 air toxics were estimated from existing databases for point, area, and mobile sources.…”

Section: Methodsmentioning

confidence: 99%

“…A growing number of reports have identified HAPs and other unregulated air pollutants as presenting a potential public health problem [e.g., (6)(7)(8)(9)(10)(11)(12)]. Based on these concerns, many states have begun monitoring concentrations of toxic air pollutants, and the U.S. EPA is planning a national monitoring network.…”

mentioning

confidence: 99%

An Assessment of Air Toxics in Minnesota

Pratt¹,

Palmer²,

Wu³

et al. 2000

Environmental Health Perspectives

View full text Add to dashboard Cite

“…This paper focuses on jointly examining the results from an air quality dispersion model, the ASPEN or Assessment System for Population Exposure Nationwide model (Rosenbaum et al, 1999;US EPA, 2000) and an inhalation exposure model, the Hazardous Air Pollutant Exposure Model, Version 5 (HAPEM), applied during the 1999 National Air Toxic Assessment (NATA) study (US EPA 2006a) for assessing exposures and risks from many particulate and gaseous HAPs in the US. The goal of our analysis is to examine the significance of the differences between modeled exposures to outdoor HAPs and the corresponding ambient pollutant concentrations that is relevant to air pollution epidemiology research.…”

Section: Introductionmentioning

confidence: 99%

“…Area sources are smaller stationary sources that emit less than 10 tons per year of a single air pollutant or less than 25 tons per year of a combination of HAPs. Examples of area sources include neighborhood dry cleaners and gas stations.Once the emissions are processed, they are input into the ASPEN model (Rosenbaum et al, 1999;US EPA, 2000 Figure 1. Components of air quality and exposure modeling tools used to calculate model predicted exposure to concentration ratios.…”

mentioning

confidence: 99%

Modeling population exposures to outdoor sources of hazardous air pollutants

Özkaynak

Palma

Touma

et al. 2007

J Expo Sci Environ Epidemiol

View full text Add to dashboard Cite

Accurate assessment of human exposures is an important part of environmental health effects research. However, most air pollution epidemiology studies rely upon imperfect surrogates of personal exposures, such as information based on available central-site outdoor concentration monitoring or modeling data. In this paper, we examine the limitations of using outdoor concentration predictions instead of modeled personal exposures for over 30 gaseous and particulate hazardous air pollutants (HAPs) in the US. The analysis uses the results from an air quality dispersion model (the ASPEN or Assessment System for Population Exposure Nationwide model) and an inhalation exposure model (the HAPEM or Hazardous Air Pollutant Exposure Model, Version 5), applied by the US. Environmental protection Agency during the 1999 National Air Toxic Assessment (NATA) in the US. Our results show that the total predicted chronic exposure concentrations of outdoor HAPs from all sources are lower than the modeled ambient concentrations by about 20% on average for most gaseous HAPs and by about 60% on average for most particulate HAPs (mainly, due to the exclusion of indoor sources from our modeling analysis and lower infiltration of particles indoors). On the other hand, the HAPEM/ASPEN concentration ratio averages for onroad mobile source exposures were found to be greater than 1 (around 1.20) for most mobile-source related HAPs (e.g. 1, 3-butadiene, acetaldehyde, benzene, formaldehyde) reflecting the importance of near-roadway and commuting environments on personal exposures to HAPs. The distribution of the ratios of personal to ambient concentrations was found to be skewed for a number of the VOCs and reactive HAPs associated with major source emissions, indicating the importance of personal mobility factors. We conclude that the increase in personal exposures from the corresponding predicted ambient levels tends to occur near locations where there are either major emission sources of HAPs or when individuals are exposed to either on-or nonroad sources of HAPs during their daily activities. These findings underscore the importance of applying exposure-modeling methods, which incorporate information on time-activity, commuting, and exposure factors data, for the purposes of assigning exposures in air pollution health studies. Keywords: air toxics, commuting, hazardous air pollutants, microenvironment, modeling, population exposure, time-activity. IntroductionEstimating human exposure is a critical component of most environmental risk assessments. Human exposures to hazardous air pollutants (HAPs) can result from contact with air, water, soils, and food. Exposures may be dominated by contact with a single medium (e.g., ambient air) or result from concurrent contacts with multiple media (e.g., air, water, soil). The nature and extent of such exposures depend largely on two things: human factors and the concentration of a pollutant in the relevant exposure media. Human factors include behavioral, sociological, and physiological characteristic...

show abstract

National Estimates of Outdoor Air Toxics Concentrations

Cited by 103 publications

References 23 publications

Source apportionment of exposure to toxic volatile organic compounds using positive matrix factorization

Source apportionment of exposure to toxic volatile organic compounds using positive matrix factorization

An Assessment of Air Toxics in Minnesota

Modeling population exposures to outdoor sources of hazardous air pollutants

Contact Info

Product

Resources

About