Grantee Research Project Results
2001 Progress Report: Characterization of Factors Determining Personal Exposure to Volatile Air Toxics in Urban Environments
EPA Grant Number: R826786Title: Characterization of Factors Determining Personal Exposure to Volatile Air Toxics in Urban Environments
Investigators: Esmen, Nurtan A. , Lynch, Robert A. , Hall, Thomas A. , Phillips, M. L. , Johnson, L. , Clinkenbeard, R.
Current Investigators: Esmen, Nurtan A. , Wang, D. , Lynch, Robert A. , Hall, Thomas A. , Johnson, D. L. , Phillips, M. L.
Institution: University of Oklahoma
Current Institution: University of Oklahoma Health Sciences Center
EPA Project Officer: Chung, Serena
Project Period: October 1, 1998 through September 30, 2001 (Extended to September 30, 2002)
Project Period Covered by this Report: October 1, 2000 through September 30, 2001
Project Amount: $559,352
RFA: Urban Air Toxics (1998) RFA Text | Recipients Lists
Research Category: Air , Air Quality and Air Toxics
Objective:
The primary objective of this research project is to investigate how external factors influence the relationship between personal exposures and area measurements of air toxics and air particulate matter. Using a multi-city, multi-season factorial design, we are studying the distribution of personal exposures in relation to different dichotomous macro-environmental and household factors, which are hypothesized to influence personal activity and exposure patterns.
Progress Summary:
Of the samples analyzed to date, more than 24 compounds were identified. In addition, 11 compounds were quantified. The results for ethylbenzene, trimethylbenzene, octane, hexane, acetone, tetrachloroethylene, and dichlorobenzene were highly censored; more than 70 percent of samples were below the limit of quantification. Statistical analysis focused on the results for toluene, benzene, p-xylene, and o-xylene. Considering each sample type (personal daytime, personal night, indoor day, indoor night, outdoor day, and outdoor night) as a separate data set, the data appear to be lognormally distributed. In most of the data sets, the noncensored data are unimodal, but several of the data sets show evidence of bimodality.
Influential factors for the personal and indoor daytime and night exposures to benzene, toluene, and o- and p-xylene were identified by calculating the contrast for each factor. In addition, a contrast was determined for homes with (N = 26) and without (N = 10) attached garages. Contrasts were not calculated for the outdoor exposures, because these data sets were more highly censored. Surprisingly, the presence of a refinery was associated with notably lower concentrations of benzene, toluene, o-xylene, and p-xylene in the personal night-time samples. Wet conditions were associated with lower concentrations of toluene, and workdays were associated with lower concentrations of p-xylene in the personal night-time samples. Mild temperature was associated with higher concentrations of benzene and o-xylene in indoor daytime samples and higher concentrations of toluene and p-xylene in indoor night-time samples. Attached garages were associated with higher concentrations of benzene in the indoor night-time samples.
The relationship between indoor and outdoor contaminant concentration ratios and the permeability of the residence also was investigated. With the possible exception of toluene, the data appear not to support the hypothesis that the tightness of the house would tend to cause elevated indoor/outdoor ratios. The correlation between normalized leakage and the absolute value of the log-transformed indoor/outdoor ratio was weakly negative for toluene (r = -0.10), weakly positive for benzene (r = 0.16) and o-xylene (r = 0.26), and essentially zero for p-xylene. It seems reasonable to interpret this finding as: if the dominant sources are external, the equilibration is faster than the sampling times, and if the sources are internal, the exposures are dominated by the internal source.
Although there are some limitations of the sampling strategy due to the unpredictability of the meteorological parameters and there are some difficulties associated with extremely low concentrations observed, the strategy developed is very applicable to extracting factors determining personal exposure. The method developed should serve well in densely populated areas of the Atlantic and Pacific Coasts and of the Great Lakes Region. The finding also suggests that the vast but sparsely populated middle section of the country is not likely to show consistently high or measurable exposures simply due to the vast dilution capacity of the local atmosphere.
Future Activities:
There are some additional, well selected samplings that will be conducted to complete the field study phase of the research. Data analysis will dominate the remainder of the project.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
Other project views: | All 27 publications | 6 publications in selected types | All 4 journal articles |
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Type | Citation | ||
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Esmen NA, Johnson DL, Agron GM. The variability of delivered dose of aerosols with the same respirable concentration but different size distributions. The Annals of Occupational Hygiene 2002;46(4):401-407. |
R826786 (2001) R826786 (Final) |
Exit Exit |
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Phillips ML, Hall TA, Esmen NA, Lynch R, Johnson DL. Use of global positioning system technology to track subject's location during environmental exposure sampling. Journal of Exposure Analysis and Environmental Epidemiology 2001;11(3):207-215. |
R826786 (2001) R826786 (Final) |
Exit Exit |
Supplemental Keywords:
monitoring, south central, particulates, air toxics, air, geographic area, health, RFA, toxics, 33/50, atmospheric sciences, biochemistry, children?s health, environmental chemistry, hazardous air pollutants, HAPs, health risk assessment, risk assessment, state, volatile organic compounds, VOCs, indoor air, indoor air quality, particulate matter, PM, Oklahoma, OK, styrene, toluene, xylenes, isomers, mixture, activity patterns, air pollutants, air pollution, ambient air, ambient air quality, children, exposure and effects, fine particle levels, fine particulates, health effects, human exposure, modeling, personal exposure, urban air pollution, benzene, gasoline, ethyl benzene, hexane, 2,2,4-trimethylpentane., RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, Air, Toxics, ENVIRONMENTAL MANAGEMENT, Geographic Area, Air Quality, particulate matter, Environmental Chemistry, Health Risk Assessment, air toxics, State, HAPS, VOCs, Risk Assessments, Biochemistry, Physical Processes, Children's Health, Atmospheric Sciences, indoor air, Ecology and Ecosystems, 33/50, Risk Assessment, ambient air quality, health effects, personal exposure, urban air toxics, Hexane, exposure and effects, Toluene, air pollutants, air quality models, ambient air, Xylenes, Ethyl benzene, fine particulates, exposure, air pollution, modeling, benzene, children, human exposure, hazardous air pollutants (HAPs), urban air pollution, PM, indoor air quality, fine particle levels, Volatile Organic Compounds (VOCs), Oklahoma (OK), 2, 2, 4-Trimethylpentane, Benzene (including benzene from gasoline), Styrene, Xylenes (isomers and mixture), activity patterns, exposure assessmentProgress and Final Reports:
Original AbstractThe 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.