Comparison of PM2.5 and PM10 monitors

An extensive PM monitoring study was conducted during the 1998 Baltimore PM Epidemiology - Exposure Study of the Elderly. One goal was to investigate the mass concentration comparability between various monitoring instrumenta tion located across residential indoor, residential outdoor, and ambient si tes. Filter-based (24-h integrated) samplers included Federal Reference Met hod Monitors (PM2.5-FRMs), Personal Environmental Monitors (PEMs), Versatil e Air Pollution Samplers (VAPS), and cyclone-based instruments. Tapered ele ment oscillating microbalances (TEOMs) collected real-time data. Measuremen ts were collected on a near-daily basis over a 28-day period during July-Au gust, 1998. The selected monitors had individual sampling completeness perc entages ranging from 64% to 100%. Quantitation limits varied from 0.2 to 5. 0 mug/m(3). Results from matched days indicated that mean individual PM10 a nd PM2.5 mass concentrations differed by less than 3 mug/m(3) across the in strumentation and within each respective size fraction. PM10 and PM2.5 mass concentration regression coefficients of determination between the monitor s often exceeded 0.90 with coarse (PM10-2.5) comparisons revealing coeffici ents typically well below 0.40. Only one of the outdoor collocated PM2.5 mo nitors (PEM) provided mass concentration data that were statistically diffe rent from that produced by a protoype PM2.5 FRM sampler. The PEM had a posi tive mass concentration bias ranging up to 18% relative to the FRM prototyp e.