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DETERMINING COARSE PARTICULATE MATTER CONCENTRATIONS: A PERFORMANCE EVALUATION OF CANDIDATE METHODOLOGIES UNDER WINTERTIME CONDITIONS
Citation:
Solomon, P A., T G. Ellestad, T L. Conner, R B. Zweidinger, M. Harmon, T. Hanley, L. Byrd, R. Scheffe, R. W. Vanderpool, R. Murdoch, S. Natarajan, C. A. Noble, J. Ambs, G. Sem, AND J. Tisch. DETERMINING COARSE PARTICULATE MATTER CONCENTRATIONS: A PERFORMANCE EVALUATION OF CANDIDATE METHODOLOGIES UNDER WINTERTIME CONDITIONS. Presented at American Association for Aerosol Research, Anaheim, CA, October 20-24, 2003.
Impact/Purpose:
Develop and evaluate methods for the sampling and analysis of PM in ambient air, with emphasis on FRM/FEM for PMc, measurement of carbonaceous aerosols, measurement of biogenic aerosols, comparisons measurements from the STN and IMPROVE monitoring networks, and continuous methods for PM mass and its chemical components.
Description:
The main objective of this study is to evaluate the performance of sampling methods for potential use as a Federal Reference Method (FRM) capable of providing an estimate of coarse particle (PMc: particulate matter with an aerodynamic diameter between 2.5 um and 10 um) mass concentrations in ambient air. Five sampling approaches are being evaluated. These approaches include a time-integrated or discrete method for measuring coarse particles directly using a sequential dichotomous sampler; a discrete difference method, which uses two FRM samplers, one to measure PM2.5 and the other PM10 with the difference, PM10-PM2.5, representing an estimate of PMc. Filters from these two sampler types are analyzed gravimetrically in the laboratory subsequent to collection. Two continuous coarse particle samplers that measure PMc directly with a time resolution of 1 hour or less and provide data in near real-time also are being evaluated. One sampler is a commercially available system based on beta attenuation, while the other is based on TEOM technology. The sequential and continuous methods use the dichotomous virtual impactor for separating fine and coarse particles. An aerodynamic particle sizer (APS) also is being evaluated that measures the aerosol size distribution in near-real time. The APS estimates ambient PMc mass concentration based on an assumed density of the measured PMc.
The samplers are being evaluated in three locations that provide diverse challenges to the samplers, including high PMc to PM10 ratios, high PM2.5 to PM10 ratios, and high and low PMc values under cold conditions. Results presented here are from a 30-day intensive monitoring effort in Gary, IN during March and April 2003. The site and timing of the study was chosen to test the samplers under cold conditions with highly variable PMc concentrations. The site was located near a steel mill that intermittently impacted the sampling site with high PMc concentrations. Meteorological conditions encountered during the study were quite variable and included periods of rain, snow, high wind speeds, and ambient temperatures ranging from -15 C to + 22 C. As measured by the FRM difference method, daily PMc concentrations ranged from 5 ug/m3 to 58 ug/m3 with a measured mean of 20 ug/m3. The minimum, mean, and maximum PM2.5 to PM10 ratios, which are an indicator of the ambient PM size distribution, ranged from 0.33 to 0.80 with a mean of 0.55.
This is an abstract of a proposed presentation and does not necessarily reflect the United States Environmental Protection Agency (EPA) policy. The actual presentation has not been peer reviewed by EPA. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.