Abstract |
To develop improved source-receptor relationships and for better understanding the causes of high PM2.5 concentrations in the atmosphere, it is necessary to not only determine concentrations of PM2.5 mass, the NAAQS indicator, but also the chemical components of PM2.5. A sampling program of this type, which will consist of up to 300 sites nationwide has been initiated by EPA Since the PM2.5 Federal Reference Method (FRM) using only Teflon filters is not suitable for determining the chemical composition of the collected aerosol, since carbon can not be directly measured (Speciation Guidance Document, 1999), EPA solicited innovative designs for speciation samplers, based on performance specifications. This led to the development of three slightly different candidate samplers manufactured by Andersen Instrument Inc., MetOne, Inc., and University Research Glassware (URG). These samplers are designed to allow for a nearly complete mass balance of the collected aerosol, while minimizing sampling artifacts for nitrate and allowing flexibility for minimizing organic carbon artifacts in the future. Due to the need to have consistency across this national network, the Speciation Expert Panel recommended a methods comparison field study among the new speciation samplers, historically used samplers, and the PM2.5 FRM. The program plan for EPA's Chemical Speciation Sampler Evaluation Study details the approach and implementation of the study. This report presents the approach and results from the 4-City intercomparison study; Phase 1, of the full evaluation of these samplers. Other Phases are described in Field Program Plan (1999) and include evaluation of denuders and reactive post filters for sampling organic aerosols with minimal artifacts, an evaluation of the chemical speciation samplers under summertime conditions, and an evaluation of the samplers under a variety of environmental conditions to test operational performance and logistics with the National Chemical
Speciation Laboratory.
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