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SHEDS-PM: A POPULATION EXPOSURE MODEL FOR PREDICTING DISTRIBUTIONS OF PM EXPOSURE AND DOSE FROM BOTH OUTDOOR AND INDOOR SOURCES
Citation:
Burke, J M., R. Vedantham, T R. McCurdy, J Xue, AND A H. Ozkaynak. SHEDS-PM: A POPULATION EXPOSURE MODEL FOR PREDICTING DISTRIBUTIONS OF PM EXPOSURE AND DOSE FROM BOTH OUTDOOR AND INDOOR SOURCES. Presented at International Society of Exposure Analysis, Stresa, Italy, September 21-25, 2003.
Impact/Purpose:
The overall objective of this research is to develop, apply, and evaluate a human exposure model for predicting population exposures to the components of particulate matter (PM) identified as potential toxic agents contributing to adverse health effects.
Description:
The US EPA National Exposure Research Laboratory (NERL) has developed a population exposure and dose model for particulate matter (PM), called the Stochastic Human Exposure and Dose Simulation (SHEDS) model. SHEDS-PM uses a probabilistic approach that incorporates both variability and uncertainty to predict distributions of PM exposure, inhaled dose, and deposited dose for a specified population. SHEDS-PM estimates the contribution of PM from both outdoor and indoor sources (e.g., cigarette smoking, cooking) to total personal PM exposure and dose.
SHEDS-PM generates a simulation population using US Census demographic data for the user-specified population, and randomly assigns each simulated individual an appropriate activity diary from NERL's Consolidated Human Activity Database (CHAD). A time series of PM exposure for each individual is determined from calculated microenvironmental PM concentrations and the time spent in each microenvironment. Inhaled dose is determined using activity-specific ventilation rates, and deposited dose is estimated using a conventional pulmonary deposition model (total deposited to three regions of the lung). Output from the SHEDS-PM model includes distributions of exposure and dose for the specified population, as well as exposure and dose profiles for each simulated individual.
An executable version of the SHEDS-PM model with a graphical user interface (GUI) is now publicly available. The GUI allows the user to define the modeling scenario of interest, to select input data files, and to modify various input parameters. The user is only required to provide ambient outdoor PM concentration data (measured or modeled), and to specify the population of interest.
This work has been partially funded by the United States Environmental Protection Agency under Contract No. 68-W-99-002 to Science Applications International Corporation. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.