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SHORT-TERM TEMPORAL VARIATION IN PM2.5 MASS AND CHEMICAL COMPOSITION DURING THE ATLANTA SUPERSITE EXPERIMENT, 1999
Citation:
Weber, R., D. Orsini, J. St. John, M. Bergin, C. S. Kiang, M. Chang, C. M. Carrico, Y. N. Lee, P. Dasgupta, J. Slanina, B. Turpin, E. Edgerton, S. Hering, G. Allen, P A. Solomon, AND W. L. Chameides. SHORT-TERM TEMPORAL VARIATION IN PM2.5 MASS AND CHEMICAL COMPOSITION DURING THE ATLANTA SUPERSITE EXPERIMENT, 1999. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION 53(1):84-91, (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:
Measurements in urban Atlanta of transient aerosol events in which PM2.5 mass concentrations rapidly rise and fall over a period of 3-6 hr are reported. The data are based on new measurement techniques demonstrated at the U.S. Environmental Protection Agency (EPA) Atlanta Supersite Experiment in August 1999. These independent instruments for aerosol chemical speciation of NO3-, SO42- , NH4+, and organic and elemental carbon (OC and EC), reconstructed the observed hourly dry PM2.5 mass to within typically 20% or better. Data from the experiment indicated that transient PM2.5 events were ubiquitous in Atlanta and were typically characterized by a sudden increase of EC (soot) and OC in the early morning or SO42- in the late afternoon. The frequent temporal decoupling of these events provides insights into their origins, suggesting mobile sources in metro Atlanta as the main contributor to early morning PM2.5 and more regionally located point SO2 sources for afternoon PM2.5 events. The transient events may also have health implications. New data suggest that short-term PM2.5 exposures may lead to adverse health effects.1 Standard integrated filter-based techniques used in PM2.5 compliance monitoring networks and in most past PM2.5 epidemiological studies collect samples over 24-hour periods and thus are unable to capture these transient events. Moreover, health-effects studies that focus on daily PM2.5 mass alone cannot evaluate the health implications of the unique and variable chemical properties of these episodes.
The United States Environmental Protection Agency through its Office of Research and Development funded and managed or partially funded and collaborated in the research described here under assistance agreement number CR824 849 to Georgia Institute of Technology. This work has been subjected to agency review and approved for publication.