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THE RELATIONSHIP BETWEEN REAL-TIME AND TIME-INTEGRATED COARSE (2.5-10MM), INTERMEDIATE (1-2.5MM), AND FINE (<2.5MM) PARTICULATE MATTER IN THE LOS ANGELES BASIN
Citation:
Geller, M. D., P. M. Fine, C. Sioutas, AND P A. Solomon. THE RELATIONSHIP BETWEEN REAL-TIME AND TIME-INTEGRATED COARSE (2.5-10MM), INTERMEDIATE (1-2.5MM), AND FINE (<2.5MM) PARTICULATE MATTER IN THE LOS ANGELES BASIN. Presented at American Association for Aerosol Research, Anaheim, CA, October 20-24, 2003.
Impact/Purpose:
The PM Supersites Program is an ambient monitoring program intended to address the scientific uncertainties associated with fine particulate matter. The main objectives of the Supersites Program are as follows: 1) characterize particulate matter in a way that contributes to the understanding of source-receptor relationships and supports development of State Implementation Plans (SIPs), 2) develop and test advanced measurement methods for potential use in national monitoring networks, and 3) support health and exposure studies by providing detailed chemical and physical data at one or more central monitoring sites.
The specific objectives of this task are to provide scientific review and coordination of the technical aspects of the Supersites Program. This includes coordination among all Supersites projects and other projects which support Supersites objectives, overseeing of the data management, and coordinating the communication of data analysis and modeling results to the scientific community and other stakeholders. Products include a number of peer-reviewed journal articles (approaching 200 or more), final reports from each project, a relational database than includes not only Supersites data, but most aerometric data collected in the continental US and SE Canada during the period July 2001 to August 2002, and a policy relevant findings synthesis entitled Key and Policy Relevant Findings from the Supersites Program and Related Studies. Also supporting the synthesis is a major international conference where results will be presented from air quality methods, measurements, modeling, and data analysis studies with similar objectives to the Supersites program and during the time period of the Supersites Program, i.e., the last 5-7 years.
Description:
Population exposure to ambient particulate matter (PM) has received considerable attention due to the association between ambient particulate concentrations and mortality. Current toxicological and epidemiological studies and controlled human and animal exposures suggest that all size fractions of PM may be responsible for observed health effects. Recently, the governments of European countries and the U.S. have been discussing a new PM1 standard. The purpose of this standard is to preclude invasion of coarse particles into the fine PM mode. This notion is predicated on evidence that suggests that PM1-2.5 is dominated by coarse PM.
In this study, coarse (PM10-PM2.5), intermodal (PM1-2.5), and fine (PM2.5) PM mass concentrations in four different sites are measured with both continuous and time-integrated sampling devices. Two source sites, USC and Downey, CA and two receptor sties, Claremont and Riverside, CA, were monitored for at least three months each. The main objective is to document both short-term and diurnal variations in ambient fine, intermodal, and coarse particulate mass concentrations with respect to each other while considering the effects of sources, weather, wind speed, and wind direction. Of particular interest are the relationships between PM1 and PM1-2.5 and coarse PM with PM1-2.5. Results show strong correlations between PM1 and intermodal PM in receptor sites. These two modes in source sites show moderate correlation (R2~0.5). The contribution of PM1-2.5 to PM2.5 shows seasonal variation with the largest contribution in the summer months, most likely due to enhanced long range transport. Coarse PM is poorly correlated with intermodal PM in USC and Riverside. The correlation is dependent upon the mass concentration at Claremont, with smaller mass concentrations being moderately-to-well-correlated. This correlation becomes moderate in Downey, most likely because the local freeway is a source of all particle sizes. Continuous data yield insight into the possibility that PM1 is growing into PM1-2.5 via a complex process that involves stagnation of the ambient aerosol during high relative humidity conditions, followed by advection during daytime hours.
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.