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Relationships between actual personal exposures and surrogate measurements of air toxics

Alan Vette1, Donald Whitaker1, Carry Croghan1, Timothy Barzyk1, Charles Rodes2, and Ron Williams1 1U.S. EPA, National Exposure Research Laboratory, RTP, NC; 2RTI International, RTP, NC

The adequacy of surrogate measures of personal exposures to air toxics has largely been unexplored. Most commonly, central-site ambient monitors have been used to approximate personal exposures in the absence of actual exposure data for volatile organic compounds (VOCs) and other air toxics, including aldehydes. The Detroit Exposure and Aerosol Research Study (DEARS) provided concurrent measurements of personal exposures, residential (indoor and outdoor) and ambient concentrations of a suite of VOCs and aldehydes. The monitored VOCs included compounds typically associated with mobile sources (1,3-butadiene, and BTEX - benzene, toluene, ethylbenzene, and xylenes) and those often associated with industrial sources such as chlorinated hydrocarbons and other aromatic compounds. The monitored aldehydes included formaldehyde, acetaldehyde and acrolein. These data were used to examine the relationship between actual personal exposures and surrogate measurements of exposures including indoor, outdoor and ambient concentrations. Understanding the relationship between actual personal exposures and surrogates of exposure has significant implications for exposure, risk and health effects assessments where actual personal exposure data may not exist or cannot be reasonably obtained. Although personal exposures to air toxics in the DEARS were much higher and more variable than when measured at residential (indoors and outdoors) and ambient sites, significant associations were found between personal exposures and surrogate measurements of exposure. Linear mixed-models, which accounted for repeated measures and mixed effects, were used to examine the relationship between personal exposures and surrogate measurements. The largest determinant of personal exposures to these air toxics was indoor concentrations; outdoor and ambient concentrations marginally improved the mixed-model estimates and in most cases were not statistically significant determinants of personal exposures in mixed-models that jointly accounted for variations in indoor, outdoor and ambient concentrations.

Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.

DEARS Home | Human Exposure & Atmospheric Sciences | Exposure Research


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