Comparison of PM_2.5 and PM₁₀ monitors

Abstract

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 instrumentation located across residential indoor, residential outdoor, and ambient sites. Filter-based (24-h integrated) samplers included Federal Reference Method Monitors (PM_2.5-FRMs), Personal Environmental Monitors (PEMs), Versatile Air Pollution Samplers (VAPS), and cyclone-based instruments. Tapered element oscillating microbalances (TEOMs) collected real-time data. Measurements were collected on a near-daily basis over a 28-day period during July–August, 1998. The selected monitors had individual sampling completeness percentages ranging from 64% to 100%. Quantitation limits varied from 0.2 to 5.0 µg/m³. Results from matched days indicated that mean individual PM₁₀ and PM_2.5 mass concentrations differed by less than 3 µg/m³ across the instrumentation and within each respective size fraction. PM₁₀ and PM_2.5 mass concentration regression coefficients of determination between the monitors often exceeded 0.90 with coarse (PM_10–2.5) comparisons revealing coefficients typically well below 0.40. Only one of the outdoor collocated PM_2.5 monitors (PEM) provided mass concentration data that were statistically different from that produced by a protoype PM_2.5 FRM sampler. The PEM had a positive mass concentration bias ranging up to 18% relative to the FRM prototype.