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L.-J. Sally Liu,¹ Michael Box,¹ David Kalman,¹ Joel Kaufman,¹ Jane Koenig,¹ Tim Larson,² Thomas Lumley,³ Lianne Sheppard,^1,3 and Lance Wallace⁴

¹Department of Environmental and Occupational Health Sciences, ²Department of Environmental and Civil Engineering, and ³Department of Biostatistics, University of Washington, Seattle, Washington, USA; ⁴U.S. Environmental Protection Agency, Reston, Virginia, USA

Abstract

In this article we present results from a 2-year comprehensive exposure assessment study that examined the particulate matter (PM) exposures and health effects in 108 individuals with and without chronic obstructive pulmonary disease (COPD) , coronary heart disease (CHD) , and asthma. The average personal exposures to PM with aerodynamic diameters < 2.5 µm (PM_2.5) were similar to the average outdoor PM_2.5 concentrations but significantly higher than the average indoor concentrations. Personal PM_2.5 exposures in our study groups were lower than those reported in other panel studies of susceptible populations. Indoor and outdoor PM_2.5, PM₁₀ (PM with aerodynamic diameters < 10 µm) , and the ratio of PM_2.5 to PM₁₀ were significantly higher during the heating season. The increase in outdoor PM₁₀ in winter was primarily due to an increase in the PM_2.5 fraction. A similar seasonal variation was found for personal PM_2.5. The high-risk subjects in our study engaged in an equal amount of dust-generating activities compared with the healthy elderly subjects. The children in the study experienced the highest indoor PM_2.5 and PM₁₀ concentrations. Personal PM_2.5 exposures varied by study group, with elderly healthy and CHD subjects having the lowest exposures and asthmatic children having the highest exposures. Within study groups, the PM_2.5 exposure varied depending on residence because of different particle infiltration efficiencies. Although we found a wide range of longitudinal correlations between central-site and personal PM_2.5 measurements, the longitudinal r is closely related to the particle infiltration efficiency. PM_2.5 exposures among the COPD and CHD subjects can be predicted with relatively good power with a microenvironmental model composed of three microenvironments. The prediction power is the lowest for the asthmatic children. Key words: asthma, CHD, COPD, infiltration efficiency, longitudinal correlation, personal cloud, PM_2.5, wood smoke. Environ Health Perspect 111:909-918 (2003) .