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Environmental Sciences
Seminar Abstract
Field and Modeling Investigations of the
Interest in determining human exposure to fine PM has intensified due to recent findings associate particulate air pollution with increased morbidity and mortality in the United States. Although people spend an average of 85 to 90 percent of their time indoors, the National Ambient Air Quality Standards for particulate matter (PM) focus on outdoor concentrations. However, the relationship between indoor and outdoor particulate levels is not well established, particularly at more detailed levels of characterization like chemical speciation and size distribution. We conducted a field study in California’s San Joaquin Valley to investigate indoor particles of outdoor origin. The objective of the study is to develop a physically-based, semi-empirical model that describes the indoor concentration of PM2.5 sulfate, nitrate, organic carbon and black carbon derived from outdoor sources. The study was conducted in an unoccupied, single-story residence in Clovis, California, manipulating the house to effectively use it as a research laboratory. Intensive measurements were performed for four weeks in the fall and winter of 2000/2001. Measurements included many of the physical and chemical properties of both the indoor and outdoor aerosol as a function of time, as well as important housing and meteorological characteristics. This study resulted in a rich chemically resolved near real-time data set that reflects the dynamic character of particle transport indoors, which is necessary to answer important question regarding exposure. Is chemical speciation of particle data required for determining exposure to particles of outdoor origin? Can we identify levels of data aggregation that are appropriate for different applications, e.g. long-term exposure to particulate matter versus individual pollutant episodes? What is the role of indoor surfaces on indoor particulate concentration? This presentation will focus on these questions, and will include some interesting results regarding the transformation of ammonium nitrate and carbonaceous aerosols in the indoor environment.
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