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2000 Progress Report: Source Apportionment of Exposure to Toxic Volatile Organic Compounds

EPA Grant Number: R826788
Title: Source Apportionment of Exposure to Toxic Volatile Organic Compounds
Investigators: Milford, Jana B. , Miller, Shelly
Institution: University of Colorado at Boulder
EPA Project Officer: Katz, Stacey
Project Period: October 1, 1998 through September 30, 2000 (Extended to June 30, 2001)
Project Period Covered by this Report: October 1, 1999 through September 30, 2000
Project Amount: $129,695
RFA: Urban Air Toxics (1998)
Research Category: Air Quality and Air Toxics

Description:

Objective:

The overall objective of the proposed research is to estimate the contributions that various sources make to human exposure to toxic volatile organic compounds (VOCs) using receptor-oriented source apportionment techniques. The study seeks to distinguish between indoor and urban area sources. The study will test multivariate techniques for extracting source profiles from exposure data, along with mass balance methods for apportioning source contributions. An additional objective of the research is to demonstrate methods for evaluating the source apportionment results using simulated exposure data and questionnaire responses from personal exposure studies.

Progress Summary:

Data from the Total Exposure Assessment Methodology (TEAM) studies conducted from 1980 to 1987 in New Jersey and California and from the 1990 California Indoor Exposure study have been acquired, processed, and analyzed using Positive Matrix Factorization (PMF). Personal exposure and outdoor concentrations of 14 and 17 toxic volatile organic compounds (VOCs) were analyzed from the New Jersey and California data sets, respectively. Two-way PMF was applied separately to personal exposure concentrations and to outdoor concentrations measured in New Jersey and California. Three-way PMF was applied to the subset of study participants in both states for which both personal and outdoor concentrations were measured. PMF was generally successful in identifying factors that could be interpreted as distinct sources, although some sources with similar compositions could not be distinguished.

For the New Jersey data, eight factors were distinguished by the three-way PMF model as contributing to outdoor concentrations, personal exposures or both. Nine factors were distinguished by the three-way PMF model for California. The two-way PMF model results for outdoor or personal exposure concentrations corresponded well to the three-way results in that for both locations the two-way analyses identified subsets of the same factors identified with the three-way model. The factors distinguished by the PMF analyses were identified by comparing the composition of emissions from known sources of the toxic VOCs with the factor profiles given by PMF. The sources found for one or both data sets were: contaminated water (trichloroethylene [TCE]); solvents (1,1,1-trichloroethane [TCA]); gasoline vapors, automobile exhaust or environmental tobacco smoke (aromatics including benzene, ethylbenzene, and xylenes); wastewater treatment plant emissions (chloroform, TCA, TCE, benzene, xylenes); drycleaning chemicals (perchloroethylene); deodorizers or mothballs (p-dichlorobenzene); consumer products (perchloroethylene, styrene, benzene, n-octane); building materials (alkanes and xylenes); background ambient concentrations (TCA, benzene, ethylbenzene, perchloroethylene, and xylenes) and cleaners ( -pinene). Of these, the major sources of toxic VOCs in both New Jersey and California 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. Good correspondence was found between the factor scores given by PMF and the activities reported by TEAM study participants for pumping gasoline, being exposed to environmental tobacco smoke, drinking tap water and visiting the dry cleaners in New Jersey, and drinking tap water, showering and using paints and solvents in California.

In addition to completing the PMF analysis, progress has been made during the past year on several other tasks. First, work continued on developing a synthetic data set to further test and compare the ability of alternative multivariate data analysis methods to identify source factors and quantify their contributions. Previously published data are being used to generate exposures from specific sources, including outdoor sources, indoor sources and personal activities. Randomly generated exposures from each source or activity are being summed for each pollutant to generate a synthetic data set of the exposures of several hundred people to a suite of VOCs. PMF will be applied to the synthetic data set, with known source profiles and contributions, to test the model. The synthetic, TEAM, and CARB data will be modeled with other receptor models as well, including principle components analysis (PCA), chemical mass balance (CMB) and the UNMIX (also known as GRACE/SAFER) model, in order to compare the results from these models with PMF results.

Future Activities:

The robustness of PMF as a source-apportionment technique for personal exposures to toxic VOCs will be further tested using the synthetic data described above. The synthetic data set will also be used to test the CMB, UNMIX, and PCA source apportionment methods. These models will then be applied to the TEAM data from California and New Jersey. A paper documenting the results of the comparison will be prepared and submitted for publication. A final report will also be prepared and submitted.


Journal Articles on this Report: 1 Displayed | Download in RIS Format

Other project views: All 7 publications 3 publications in selected types All 3 journal articles

Type Citation Project Document Sources
Journal Article Larson TV, Gould T, Simpson CD, Liu L-JS, Claiborn C, Lewtas J. Source apportionment of indoor, outdoor, and personal PM2.5 in Seattle, Washington, using positive matrix factorization. Journal of the Air & Waste Management Association 2004;54(9):1175-1187. R826788 (2000)
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R827355 (2004)
R827355 (Final)
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R827355C008 (2003)
R827355C008 (Final)
R827355C010 (Final)
  • Abstract from PubMed
  • Other: AWMA PDF
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    • Supplemental Keywords:

    indoor air, exposure, VOCs, toxics, modeling. , Toxics, ENVIRONMENTAL MANAGEMENT, Air, Health, Risk Assessment, indoor air, Risk Assessments, HAPS, air toxics, area source program, Chloroform, exposure assessment, urban air pollutants, airborne urban contaminants, 1, 4-Dioxane (1, 4-Diethyleneoxide), Chlorobenzene, indoor air quality, Volatile Organic Compounds (VOCs), chemical composition, hazardous air pollutants (HAPs), human health risk, 1, 4-Dichlorobenzene(p), air pollutants, source apportionment, 1, 1, 2, 2-Tetrachloroethane, air pollution, Bromoform, carbon tetrachloride, Ethylene dibromide (Dibromoethane), modeling, o-Xylenes, Xylenes (isomers and mixture), positive matrix factorization, Benzene (including benzene from gasoline), human exposure

    Progress and Final Reports:
    Original Abstract
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    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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