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CHARACTERIZATION OF INDOOR-OUTDOOR AEROSOL CONCENTRATION RELATIONSHIPS DURING THE FRESNO PM EXPOSURE STUDIES
Citation:
Vette, A F., A W. Rea, P. A. Lawless, C. E. Rodes, E G. Evans, V R. Highsmith, J P. Creason, AND L S. Sheldon. CHARACTERIZATION OF INDOOR-OUTDOOR AEROSOL CONCENTRATION RELATIONSHIPS DURING THE FRESNO PM EXPOSURE STUDIES. AEROSOL SCIENCE AND TECHNOLOGY 34(1):118-126, (2001).
Impact/Purpose:
The objective of this task is to develop and employ PM measuring tools for EPA researchers and regulators to use to characterize the exposure of humans to PM of outdoor origin in both outdoor and indoor environments. Achieving these objectives will improve the scientific foundation for risk assessments of PM in future reevaluations of the NAAQS and in assessing exposure of humans to PM.
Description:
Particle size distributions were measured indoors and outdoors of a single, detached residence during the Fresno particulate matter exposure studies in winter (February 1-28, 1999) and spring (April 18-May 16, 1999). Data was collected for particle sizes ranging from about 0.01 to 2.5 wm. These data were used to investigate the temporal relationships between indoor and outdoor aerosol concentrations and to determine particle deposition rates and penetration factors for discrete particle sizes. Indoor/outdoor aerosol concentration ratios for particle sizes > 1 wm were diurnally variable with highest ratios occurring during daytime (6:00-18:00) due to resuspension from indoor activities. Daytime and nighttime (19:00-7:00) aerosol concentration ratios were very similar for particle sizes < 1 wm. Particle deposition rates were determined by measuring the decay in indoor aerosol concentrations after indoor levels were elevated by infiltration of native ambient aerosols. Deposition rates varied depending on particle size and were consistent with model results up to about 0.4 wm. The experimentally determined deposition rates were considerably higher than model results at larger particle sizes, suggesting the possibility of an additional indoor loss mechanism. Penetration factors were determined to be less than unity for all particle sizes and ranged from 0.5 to 0.9.
The U.S. Environmental Protection Agency through its Office of Research and Development funded and managed the research described here under contract #68-D5-0040 to the Research Triangle Institute. It has been subjected to agency review and approved for publication. Mention of trade names or commercial products does not constitute an endorsement or recommendation for use.