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Exposures To Volatile Organic Compounds In A Source Impacted Airshed
Alan Vette1, Donald Whitaker1, Carry Croghan1, Carvin Stevens1, Charles Rodes2, Karen Oliver3, Herb Jacumin3 and Ron Williams1
1 - U.S. EPA, National Exposure Research Laboratory, RTP, NC
2 - RTI International, RTP, NC; 3 Alion Science and Technology, RTP, NC
The Detroit Exposure and Aerosol Research Study (DEARS) is a three-year monitoring study designed to assess the impacts of local industrial and mobile sources on residential areas in Wayne County, Michigan. Daily integrated (24-hr) samples are being collected of personal exposure, and residential indoor and outdoor concentrations in five neighborhoods throughout Detroit and Wayne County. Concurrent samples are being collected for comparison at a central community ambient monitoring location and a regional background site. Samples are collected over seven-week periods during summer and winter each year and analyzed for particulate matter (PM) and air toxics, including volatile organic compounds (VOCs). The fundamental objectives of the DEARS are to determine the magnitude and variability of source impacts on personal exposures and residences and to determine the relationship between exposures and a central-site community based monitor. The study is aimed at determining the factors influencing exposures to air pollutants of outdoor origin, including volatile organic compounds (VOCs) and particulate matter. Data from the first half of the DEARS (three seasons) is presented here along with preliminary statistical analyses. Personal exposures to most VOCs were higher than concentrations measured indoors, outdoors and at the central monitoring site. Seasonal differences were observed in personal exposures and residential indoor and outdoor concentrations with levels generally higher in summer than winter. Spatial differences in outdoor VOC concentrations were found between monitoring areas as compared to the central community monitoring site and a regional background site. Mobile source impacts were also observed for some compounds, which were significantly higher when the residence was downwind from a major roadway. Although personal exposures to VOCs were much higher and more variable than when measured indoors and outdoors, significant associations were found between personal exposures and indoor/outdoor concentrations. This suggests that indoor and outdoor concentrations are significantly related to personal exposures. However, the magnitude of the relationship decreased considerably between indoors and outdoors. Personal exposures were most closely related to indoor concentrations, consistent with the amount of time the DEARS participants spent indoors (> 85%).
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