Modeling personal and ambient exposures to air toxics in Camden, New Jersey
S.W. Wang, X. Tang, Z. Fan, P.J. Lioy, P.G. Georgopoulos
Environmental & Occupational Health Sciences Institute, Piscataway, NJ
This study presents the Individual Based Exposure Modeling (IBEM) application of the MENTOR-1A [Modeling ENvironment for TOtal Risk studies (MENTOR) using a "One Atmosphere" (1A) setting] system in the toxic "hot-spot" area of Camden, NJ to characterize the ambient and personal exposure levels to three air toxics (benzene, toluene, and formaldehyde). The IBEM application of the MENTOR system took into account subject-specific information collected from the field study such as demographic, housing characteristics, and time-activity patterns, etc. to estimate personal exposures in the framework of a source-to-exposure sequence. First, the emissions-based ambient concentrations of air toxics at the location of residence for each subject were estimated using atmospheric dispersion models, specifically the Industrial Source Complex Short Term Version 3 (ISCST3) and the AMS/EPA Regulatory Model (AERMOD). Both calculated and measured outdoor concentrations during the study were then combined with information from activity diaries completed by the subject as inputs to the MENTOR-1A system for estimating the personal exposures resulting from outdoor sources. The modeling results were compared to the measurements of neighborhood and personal air concentrations collected in a field study for model evaluation. The strength of the MENTOR-IBEM approach involves the use of local ambient measurements and subject-specific time-activity pattern data to estimate the percentage contributions of air toxics to personal exposures resulting from ambient sources, which has not been pursued in previous studies. This approach can also facilitate the interpretation of factors such as location, day-of-the-week, and seasonal effects on personal exposure measurements.
This work is funded in part by the Health Effects Institute (HEI), the American Chemistry Council (ACC), and the USEPA (Cooperative Agreement CR-83162501). Viewpoints expressed here are the responsibility of the authors and do not necessarily reflect the views of HEI, ACC, USEPA, or their contractors.