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FIELD EVALUATION OF A SAMPLING APPROACH FOR PM-COARSE AEROSOLS
Citation:
Noble, C. A., R. W. Murdoch, S. Natarajan, R. W. Vanderpool, D B. Gemmill, AND R W. Wiener. FIELD EVALUATION OF A SAMPLING APPROACH FOR PM-COARSE AEROSOLS. Presented at American Association for Aerosol Research, Portland, OR, October 15-19, 2001.
Impact/Purpose:
The Reference and Equivalency Program accepts and evaluates applications for new FRMs/FEMs and designates those that meet the criteria. In addition, the Program publishes required guidance and quality assurance (QA) documents in the Federal Register and addresses technical or application issues in which the integrity of FRM/FEM monitors is questioned.
Description:
Subsequent to a 1997 revision of the national ambient air quality standards (NAAQS) for particulate matter (PM), the US Environmental Protection Agency is investigating the development of sampling methodology for a possible new coarse particle standard. When developed, this method will measure the mass concentration of particles in the size range of 2.5-10 um in diameter. Although the PM-coarse measurement methodology has yet to be finalized, a numerical difference method between collocated PM10 and PM2.5 samplers is being considered.
To investigate the feasibility of the difference method for PM-coarse measurement, field studies were conducted at Research Triangle Park, NC, Rubidoux, CA, Phoenix, AZ, Philadelphia, PA, and Windsor, CT. These five sites provided a broad range of chemically and physically diverse ambient PM. Each of the five field campaigns consisted of fifteen consecutive days of sampling. At each site, three pairs of PM10 and PM2.5 samplers were collocated, with each pair being from a different manufacturer. Refrigerated samples were sent back to the laboratory for gravimetric analysis after every fifth sampling day.
As expected, Rubidoux and Phoenix had the highest concentration measurements of PM-coarse. Ambient concentrations for coarse PM ranged from 2 ug per cubic meter in Windsor, to 59 ug per cubic meter in Rubidoux for single day measurements. The relative contribution of coarse PM to the PM10 measurements was greatest in Rubidoux and Phoenix, where there were relatively high amounts of airborne crustal material. The PM2.5/PM10 ratio ranged from 0.22 at Phoenix to 0.70 at Philadelphia. These field studies demonstrated that a subtraction method utilizing results from independent PM10 and PM2.5 sampling devices provide results with an acceptable level of precision. As expressed by the coefficient of variation, mean precision at the five sites for PM10, PM2.5, and PM-coarse were approximately 5%, 3%, and 9%, respectively.
This abstract has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.