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DETERMINING PARTICLE EMISSION SOURCE STRENGTHS FOR COMMON RESIDENTIAL INDOOR SOURCES USING REAL-TIME MEASUREMENTS AND PIECEWISE-CONTINUOUS SOLUTIONS TO THE MASS BALANCE EQUATION
Citation:
Ott, W R., P. Switzer, N. Klepeis, V Zartarian, AND M. Brauer. DETERMINING PARTICLE EMISSION SOURCE STRENGTHS FOR COMMON RESIDENTIAL INDOOR SOURCES USING REAL-TIME MEASUREMENTS AND PIECEWISE-CONTINUOUS SOLUTIONS TO THE MASS BALANCE EQUATION. Presented at ISEA 2000 Exposure Analysis in the 21st Century: Integrating Science, Policy and Quality of Life, Monterey Peninsula, CA, October 24-27, 2000.
Impact/Purpose:
The primary objective of this research is to improve current PM population exposure models to more accurately predict exposures for the general population and susceptible sub-populations. Through model improvements, a better understanding of the major factors controlling exposure to PM will be achieved. Specific objectives of this research are to:
- predict total personal exposure to PM10 and PM2.5 for the general and for susceptible sub-populations residing in different urban environments
- estimate the contribution of ambient PM to predicted total PM exposures
- determine what factors are of primary importance in determining PM exposures, including an analysis of the effects of time spent in various microenvironments and the importance of spatial variability in ambient PM concentrations
- determine what factors contribute the greatest uncertainty to model predictions and make recommendations for measurement and modeling studies to reduce these uncertainties
- predict daily and annual average exposures using single or multi-day time-activity diaries
- incorporate state-of-the-art dosimetric models of the lung into PM population exposure and dose models
- evaluate models against measured data from PM panel and other exposure measurement studies
- develop exposure and dose metrics applicable to acute and chronic environmental epidemiology studies
Description:
A variety of common activities in the home, such as smoking and cooking, generate indoor particle concentrations. Mathematical indoor air quality models permit predictions of indoor pollutant concentrations in homes, provided that parameter values such as source strengths and decay rates are known. This paper investigates the use of piecewise-continuous solutions to the indoor mass balance model in conjunction with real-time measurements during experimental "controlled releases" of common indoor sources to estimate the values of source strength parameters. The real-time experimental data include mass concentrations for particles less than 2.5 micrometers (PM-2.5) and less than 3.5 micrometers (PM-3.5, or Respirable Suspended Particles, RSP) measured at 1-minute time intervals. The analysis of experimental data for determining source emission compares the "peak-estimation" approach with the "area-under-the-curve" approach, and discusses how nonuniformity of mixing caused by microplume activity can be addressed. The experiments include a variety of cooking activities (frying hamburgers, preparing steak dinner, cooking Cajun chicken, burning popcorn, making toast), smoking regular and "smokeless" cigarettes, and burning candles and incense. The results indicate that different types of cooking activity of the same food type produce great differences in source emission strengths, while repeatedly smoking the same brand of cigarette causes less variation in source emission rates. Characterizing cooking activity by a "char index" may be helpful for explaining the variability in source emissions for some foods, such as toast. Future research on exposure models may require better knowledge of indoor activity patterns and the manner in which the variability of activities affects indoor particle emissions, as well as stochastic methods to handle this variability of source emissions.
This abstract has been reviewed in accordance with the U.S. Environmental Protection Agency's peer and administrative review policies and approved for presentation and publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.