| The Contributions of Emissions and Spatial Microenvironments to Exposure to Indoor Air Pollution from Biomass Combustion in Kenya Majid Ezzati,1,2,* Homayoun Saleh,1,3 and Daniel M. Kammen2,4 1Science, Technology, and Environmental Policy Program, Princeton University, Princeton, New Jersey, USA
2Mpala Research Centre, Nanyuki, Laikipia, Kenya
3Program in Applied and Computational Mathematics, Princeton University, Princeton, New Jersey, USA
4Energy and Resources Group, University of California, Berkeley, California, USA Abstract
Acute and chronic respiratory diseases, which are causally linked to exposure to indoor air pollution in developing countries, are the leading cause of global burden of disease. Efforts to develop effective intervention strategies and detailed quantification of the exposure-response relationship for indoor particulate matter require accurate estimates of exposure. We used continuous monitoring of indoor air pollution and individual time-activity budget data to construct detailed profiles of exposure for 345 individuals in 55 households in rural Kenya. Data for analysis were from two hundred ten 14-hour days of continuous real-time monitoring of concentrations of particulate matter  10 µm in aerodynamic diameter and the location and activities of household members. These data were supplemented by data on the spatial dispersion of pollution and from interviews. Young and adult women had not only the highest absolute exposure to particulate matter (2,795 and 4,898 µg/m3 average daily exposure concentrations, respectively) but also the largest exposure relative to that of males in the same age group (2.5 and 4.8 times, respectively) . Exposure during brief high-intensity emission episodes accounts for 31-61% of the total exposure of household members who take part in cooking and 0-11% for those who do not. Simple models that neglect the spatial distribution of pollution within the home, intense emission episodes, and activity patterns underestimate exposure by 3-71% for different demographic subgroups, resulting in inaccurate and biased estimations. Health and intervention impact studies should therefore consider in detail the critical role of exposure patterns, including the short periods of intense emission, to avoid spurious assessments of risks and benefits. Key words: Africa, biomass combustion, exposure assessment, field study, household energy, indoor air pollution, particulate matter, public health. Environ Health Perspect 108:833-839 (2000) . [Online 27 July 2000] Corrected on 18 August 2000. http://ehpnet1.niehs.nih.gov/docs/2000/108p833-839ezzati/ abstract.html Address correspondence to M. Ezzati, Global Programme on Evidence for Health Policy, World Health Organization, CH-1211 Geneva 27, Switzerland. Telephone: 41 22 791 2369. Fax: 41 22 791 4328. E-mail: ezzatim@who.ch *Current address: Global Programme on Evidence for Health Policy, World Health Organization, Geneva, Switzerland. We thank B. Mbinda, M. Egelian, P. Ekuam, M. Lokeny, and J. Ngisirkale for invaluable assistance in data collection, and the residents of Mpala Ranch for their hospitality, which made data collection possible. This paper has benefited from comments by N. Goldman and three anonymous reviewers. This research was supported by grants from the Summit and Compton Foundations, the Social Science Research Council, and Princeton University's Council on Regional Studies and Center of International Studies (through a grant from the MacArthur Foundation) . The African Academy of Sciences provided generous institutional support in Kenya. Received 18 January 2000 ; accepted 17 April 2000. Correction was made on 31 July, 2000.
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