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TOTAL HUMAN EXPOSURE MODEL (THEM) FOR RESPIRABLE SUSPENDED PARTICLES (RSP)
Citation:
Klepeis, N., W. Ott, AND P. Switzer. TOTAL HUMAN EXPOSURE MODEL (THEM) FOR RESPIRABLE SUSPENDED PARTICLES (RSP). U.S. Environmental Protection Agency, Washington, D.C., EPA/600/A-94/146.
Description:
A Total Human Exposure Model (THEM) has been developed that calculates 24-hour profiles using real human activity patterns and indoor air models derived from actual measurements of pollutants. HEM was designed for implementation on personal computers. urrently, the model uses the California Activity Pattern (CAP) database obtained from the Air Resources Board. hese data include diaries of over 1700 adults and children that contain coded information on locations and activities. he diary codes correspond to locations in factories, offices, restaurants and homes (room specific) and activities such as cooking, cleaning, and being in the presence of a smoker. HEM determines RSP exposure by taking the location and activity information from the CAP data and assigning RSP levels for (1) Environmental Tobacco Smoke (ETS), (2) cooking, (3) cleaning, and (4) ambient levels (from motor vehicles and wood smoke). ctual RSP levels are obtained from real microenvironmental measurements conducted recently in over 300 locations. or ambient data, actual hourly diurnal particulate measurements are obtained from a continuous monitoring instrument. HEM computes RPS exposure from ETS using validated models based on the mass balance equation. ource strengths, smoking rates, room air exchange rates and room volumes are incorporated into the model by randomly sampling from actual distributions of data. everal runs of the program were executed for the San Francisco Bay Area. aily and hourly averages were obtained from minute-by-minute exposures calculated for each person, whereupon the frequency distribution and summary statistics across the population were calculated.