Individual particle analysis of indoor, outdoor, and community samples from the 1998 Baltimore particulate matter study

The United States Environmental Protection Agency (US EPA) recently conduct ed the 1998 Baltimore Particulate Matter (PM) Epidemiology-Exposure Study o f the Elderly. The primary goal of that study was to establish the relation ship between outdoor PM concentrations and actual human PM exposures within a susceptible (elderly) subpopulation. Personal, indoor, and outdoor sampl ing of particulate matter was conducted at a retirement center in the Towso n area of northern Baltimore County. Concurrent sampling was conducted at a central community site. The main objective of this work was to use compute r-controlled scanning electron microscopy (CCSEM) with individual-particle X-ray analysis to measure the chemical and physical characteristics of geol ogical and trace element particles collected at the various sampling locati ons in and around the retirement facility. The CCSEM results show that the relative abundances of some geological and trace element particle classes identified at the outdoor and community loca tions differ from each other and from the indoor location. Particle images acquired during the computer-controlled analyses played a key role in the i dentification of certain particle types. Review of these images was particu larly useful in distinguishing spherical particles (usually indicative of c ombustion) from nonspherical particles of similar chemical composition. Pol lens and spores were also identified through a manual review, of the partic le images. Published by Elsevier Science Ltd.