January-February 2000, Volume 10, Issue 1, Pages 15 - 26

Article

Indoor/outdoor PM10 and PM2.5 in Bangkok, Thailand FENG C. TSAI1, KIRK R. SMITH1, NUNTAVARN VICHIT-VADAKAN2, BART D. OSTRO3, LAURAINE G. CHESTNUT4 & NIPAPUN KUNGSKULNITI5 1School of Public Health, University of California, Berkeley, California     2College of Public Health, Chulalongkorn University, Bangkok, Thailand     3California Environmental Protection Agency, Berkeley, California     4Stratus Consulting Inc., Boulder, Colorado     5Faculty of Public Health, Mahidol University, Bangkok, Thailand     Correspondence to: KIRK R. SMITH, School of Public Health, 140 Warren Hall, Berkeley, CA 94720-7360. Tel.: (510)643-0793. Fax: (510)642-5815. E-mail: krksmith@uclink4.berkeley.edu

Keywords

Bangkok;   indoor-outdoor relationship;   particulate matter

Abstract

Twenty-four-hour averaged PM10 and PM2.5 concentrations were obtained by using 4-liter-per-minute-pumps and impactors in microenvironments of a busy shopping district and a university hospital campus. In both areas, most people live directly adjacent to their worksites -- minimizing the need to measure commuting exposure as part of total daily exposure. Co-located samplers were set in indoor microenvironments, the near-ambient zone of the households, and at nearby streetside central ambient monitoring stations. Smoking and use of other indoor PM sources were recorded daily via questionnaires. Consistent with previous studies, smoking and the use of charcoal stoves increased indoor particulate matter levels. The sampled air-conditioned hospital area had substantially lower particle concentrations than outdoors. A simple total exposure model was used to estimate the human exposure. The averaged ratios of co-located PM2.5/PM10 concentrations in various microenvironments are reported for each location. A single daily indoor average PM10 concentration for all households measured in a given sampling day is calculated for correlation analysis. Results showed that day-to-day fluctuations of these calculated indoor PM10 levels correlated well with near-ambient data and moderately well with ambient data collected at the nearby central monitoring site. This implies that ambient monitors are able to capture the daily variations of indoor PM levels or even personal exposure and may help explain the robust association of ambient PM levels and health effects found in many epidemiological studies. Absolute PM exposures, however, were substantially underestimated by ambient monitors in the shopping district, probably because of strong local sources. Journal of Exposure Analysis and Environmental Epidemiology (2000) 10, 15-26.

Received 6 January 1999; Accepted 16 May 1999

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