United States Environmental Protection Agency Office of Research and Development National Exposure Research Laboratory FY02 Research Abstract Government Performance Results Act (GPRA) Goal 1 APM21 Significant Research Findings: Interim Report on Personal and Residential Particulate Matter Gaseous Co-pollutant Air Concentrations for Potentially Sensitive Individuals and their Association with Ambient Sources Scientific Problem and Policy Issues In 1998, the U.S. Environmental Protection Agency (EPA) Administrator issued new National Ambient Air Quality Standards (NAAQS) for PM2 5 (particulate matter less than 2.5 micrometers in diameter) based on findings from epidemiological studies that demonstrated a link between increased levels of ambient PM25 and excess mortality. Following this issuance, Congress directed the National Research Council (NRC) to determine the most important research priorities for PM to be addressed by EPA. Some of the epidemiological studies that formed the basis for the new NAAQS PM2 5 standard suggested that ambient levels of gaseous co-pollutants (e.g., CO, 03, and N02) may have confounded the relationship between PM2 5 and mortality. This is reflected in NRC Research topic #1: " What are the quantitative relationships between concentrations of particulate-matter and gaseous copollutants measured at stationary outdoor air-monitoring sites, and the contributions of these concentrations to actual personal exposures, especially for potentially susceptible subpopulations and individuals?" Research Approach The National Exposure Research Laboratory (NERL) conducted exposure studies in Baltimore, Maryland and Research Triangle Park (RTP), North Carolina to determine the relationships between actual personal exposures and ambient concentrations of PM and gaseous co-pollutants (e.g., 03, CO, and N02). This report summarizes preliminary findings from the NERL PM Longitudinal Panel Studies. The objective of the NERL Longitudinal PM Panel Studies was to characterize the relationships between personal exposures, residential indoor, and ambient concentrations of PM2 5 and associated gaseous co- pollutants (03, CO, and N02). A primary focus of the studies was to determine the factors that affect the variability and, specifically, the contribution of ambient concentrations to personal exposures of PM2 5 and gaseous co-pollutants. National Exposure Research Laboratory — November 2002 ------- The Baltimore study was conducted over a 28-day period during the summer of 1998 in a high-rise retirement facility involving an elderly (ages > 65) cohort of 20 subjects. The study included measurements of PM25 and N02 personal exposures and measurements of PM2 5, 03, CO, and N02 at a central indoor location and at a central ambient site. The RTP study was conducted over four seasons from June 2000 to June 2001 involving two cohorts: 27 African-Americans with controlled hypertension living in a low/moderate socioeconomic status area in southeast Raleigh, North Carolina and 8 mixed- race individuals with implanted cardiac defibrillators living in and near Chapel Hill, North Carolina. Measurements were made of personal exposure (PM2.5 and 03), indoors at each participant's residence (PM25, CO, and N02) and at a central ambient monitoring site (PM2 5, 03, CO, and N02) for seven days over each of the four seasons. The results from the exposure studies were summarized using general univariate statistics, and, in the RTP study, time-series regression analyses and mixed-model analyses were used to quantify the relationships between ambient, indoor, and personal exposures to PM2, and the gaseous co-pollutants. Results and Results from the studies indicated ambient levels of PM2 5 and 03 were Implications similar in RTP and Baltimore (comparison of summer season only). Personal PM2, exposures, however, were about two-fold higher in Baltimore than in RTP. Indoor levels of 03 in both studies represented only about 10% of the corresponding outdoor 03 levels. Ambient levels of CO were about two-fold higher in Baltimore while ambient N02 was about two-fold higher in RTP. In both studies, similar correlations existed between ambient levels of PM2 5 and the ambient gaseous co-pollutants. Relationships between personal exposures, indoor concentrations, and ambient concentrations also were comparable between Baltimore and RTP. In RTP, concentrations of ambient gaseous pollutants (03, CO, and N02) were poor predictors of personal exposures to the gases themselves. In fact, ambient 03 served as a better predictor of personal PM2 5 exposures than it was for personal 03 exposures. Of all the pollutants, PM2 5 was the only one for which there were significant relationships between ambient concentrations, indoor concentrations, and personal exposures. These results suggest that ambient 03 acted as a surrogate of personal PM2 5 exposures. Ambient CO and N02 acted as neither confounders nor surrogates of personal exposures. This is important because it suggests that confounding of ambient gaseous co-pollutants with ambient PM2 5 may exist, but personal exposures are not affected by such relationships. These findings are very important for epidemiologists because they show that observed health effects are not confounded by ambient concentrations of the gaseous co-pollutants because levels of ambient gases are poorly associated with personal exposures. This research output will benefit scientists and policy experts in the Office of Air Quality Planning and Standards, the National Center for Exposure National Exposure Research Laboratory — November 2002 ------- Assessment, and others in the Office of Research and Development. This work contributes to the Government Performance Results Act (GPRA) Goal 1.1.8- Conduct NAAQS Related Research and contributes to the FY02 APM 21. The NERL Longitudinal PM Panel Studies were designed and conducted by research teams at the U.S. EPA's National Exposure Research Laboratory and the U.S. EPA's National Health and Environmental Effects Research Laboratory Extramural federal funding for this research was administered under EPA cooperative assistance agreement CR820076 (University of North Carolina- Chapel Hill) as well as EPA contracts 68-D5-0040, 68-D-99-012 (Research Triangle Institute), 68-D2-0134 (QST Environmental), and 68-D2-0187 (SRA Technologies). Examples of recent publications from this study include: Williams, R., Suggs, J., Sheldon, L., Saraiya, N., Evans, G., Creason, J., Rodes, C., and Lawless, P. "Comparison of gaseous criteria air pollutants and particulate matter concentrations involving an elderly subject population in a Baltimore panel study." Proceedings of the International Symposium on Measurement of Toxic and Related Pollutants. Research Triangle Park, NC, September 14, 2000. Vette, A. F., Rea, A. W., Suggs, J., and Williams, R. W. "Gaseous Co-Pollutants Associated with Particulate Matter - Results from the NERL RTP PM Panel Study." Presented at the 12th annual conference of the International Society of Exposure Analysis Vancouver, BC Canada. August, 2002. Future Research Finalized datasets will be developed and made publically available in FY03. The analyses conducted on the RTP data set (time-series regression and mixed-model analyses) will be extended to the Baltimore study. These results will be summarized in manuscripts that will be submitted to the peer- reviewed literature. A final APM report will be presented in FY03 summarizing the results of the overall effort. Research Collaboration and Publications National Exposure Research Laboratory — November 2002 ------- Contacts for Questions and inquiries on NERL's PM Panel Studies related to gaseous co- Additional pollutants can be directed to: Information Alan Vette US EPA Office of Research and Development National Exposure Research Laboratory, MD E205-04 Research Triangle Park, NC 27711 Phone: 919/541-1378 E-mail: Vette.Alan@epamail.epa.gov Ron W. Williams US EPA Office of Research and Development National Exposure Research Laboratory, MD E205-04 Research Triangle Park, NC 27711 Phone: 919/541-2957 E-mail: Williams.Ronald@epamail.epa.gov Roy Zweidinger US EPA Office of Research and Development National Exposure Research Laboratory, MD-E205-03 Research Triangle Park, NC 27711 Phone: 919/541-2324 E-mail :zwei dinger.roy@epa.gov National Exposure Research Laboratory — November 2002 ------- |