Emily Lei Kang
N.C. State University
In 1997 the United States Environmental Protection Agency promulgated exposure standards for outdoor fine particle pollution (particulate matter less than 2.5 microns in diameter – PM2.5). This regulation was challenged in court but was eventually upheld by the Supreme Court in 2001. Nonetheless, enforcement of the regulation was delayed until further research could be completed. At that time, a study of asthma among inner-city children was being conducted for the National Institutes of Health by Rho, Inc (Chapel Hill) in seven major urban areas around the country. The federal government in collaboration with industry partners set aside more than $50 million for research into the health effects of PM2.5.
The NIH Inner City Asthma Study received additional funding to explore the impact of PM2.5 among its population of highly vulnerable children with asthma. Pollution data (including PM2.5) were gathered in the homes of 335 children with asthma in the 7 US cities. These data were collected over two-week measurement periods, 3 times, at 6-month intervals. These data constitute the largest measurement of fine particulate matter pollution ever collected in homes of children with asthma. A manuscript describing the baseline data from this study is attached.
We know that outdoor pollution can exacerbate asthma morbidity among children and may even be a causal factor for asthma development. Less is known about the effects of indoor pollution, but we know that children spend approximately 90% of their time indoors and the levels of indoor pollution (see Wallace, et al, 2003, attached) can be dramatically higher than outdoor levels. Unfortunately, direct measurement of indoor exposure is costly and difficult to obtain. However, outdoor particulate matter exposure data is readily available for most major U.S. cities and we know that outdoor air pollution contributes to indoor concentration levels. These outdoor data, in combination with behavioral questionnaire data (such as smoking, cleaning, cooking, air conditioning us, etc.) may allow us to predict indoor levels of pollution without the cost and difficulty of home visits and direct home pollution measurements.
The goal of this project is to explore a prediction model for indoor pollution based upon the extensive data available from the Inner City Asthma Study. Direct measurements of indoor PM2.5, nicotine, ozone are available in this database as are extensive behavioral diaries of home activities. These data, along with daily outdoor PM2.5 and other pollution measurements gathered from the EPA’s Aerometric Information Retrieval System (AIRS), will be used to develop a predictive model of indoor PM2.5. If it can be established that indoor PM2.5 can be predicted from outdoor PM2.5 accurately, the enormous costs and complications of direct indoor exposure data collection may be minimized for future health effects studies.
Further information regarding the Inner City Asthma Study may be found on the following website: http://www.icasweb.org/
Wallace LA, Mitchell H, O’Connor G, Neas LM, Lippmann M, Kattan M, et al. Particle concentrations in inner-city homes of children with asthma: The effect of smoking, cooking, and outdoor pollution. Environmental Health Perspectives 2003; 111(9): 1265-1272.