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AEROSOL CONCENTRATIONS DURING THE 1999 FRESNO EXPOSURE STUDIES AS FUNCTIONS OF SIZE, SEASON, AND METEOROLOGY
Citation:
Lawless, P. A., C. E. Rodes, G F. Evans, L S. Sheldon, AND J P. Creason. AEROSOL CONCENTRATIONS DURING THE 1999 FRESNO EXPOSURE STUDIES AS FUNCTIONS OF SIZE, SEASON, AND METEOROLOGY. Presented at PM 2000 AWMA Conference, Charleston, SC, January 24-28, 2000.
Description:
The 1999 Fresno exposure studies took place in February (winter season) and April/May (spring season) for two periods of four weeks. During that time, nearly-continuous measurements of outdoor aerosol concentrations were made with a scanning mobility spectrometer (TSI SNIPS) and an optical particle counter (PMS LASX). These instruments provide particle size distribution information from about 0.01 to 3 um.
The size distributions from the two sampling periods possessed similarities, but also substantial differences. In the winter test period the majority of PM2.5, mass was attributed to submicron aerosol assumed to be primarily ammonium nitrate, with very little contribution from larger sizes. In the spring test period the submicron mass contribution was much smaller, and a substantial part of the PM2.5 mass came from the coarse particle mode.
The paper examines the size distributions in detail over the test period and compares the computed PM2.5 mass concentrations to those from a collocated FRM sampler. The seasonal and diurnal dependencies of other submicron fractions are also examined. These include PM 0.1, PM-0,3 and PM1, By use of air mass trajectory modeling and meteorological data, probable sources of the particulate matter fractions can be assigned.
The results of the study show that the SNIPS-LASX instrument combination is potentially a valuable tool for PM concentration measurements, particularly for identifying components of the PM2.5 aerosol.
This work has been funded wholly or in part by the U.S. Environmental Protection Agency under contract 68-D5-0040 to the Research Triangle Institute. It 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.