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GASEOUS CO-POLLUTANTS ASSOCIATED WITH PARTICULATE MATTER-RESULTS FROM THE NERL RTP PM PANEL STUDY
Citation:
Vette, A F., A W. Rea, AND R Williams. GASEOUS CO-POLLUTANTS ASSOCIATED WITH PARTICULATE MATTER-RESULTS FROM THE NERL RTP PM PANEL STUDY. Presented at International Society of Expsure Analysis 2002 Conference, Vancouver, Canada, August 11-15, 2002.
Impact/Purpose:
The primary study objectives are:
1.To quantify personal exposures and indoor air concentrations for PM/gases for potentially sensitive individuals (cross sectional, inter- and intrapersonal).
2.To describe (magnitude and variability) the relationships between personal exposure, and indoor, outdoor and ambient air concentrations for PM/gases for different sensitive cohorts. These cohorts represent subjects of opportunity and relationships established will not be used to extrapolate to the general population.
3.To examine the inter- and intrapersonal variability in the relationship between personal exposures, and indoor, outdoor, and ambient air concentrations for PM/gases for sensitive individuals.
4.To identify and model the factors that contribute to the inter- and intrapersonal variability in the relationships between personal exposures and indoor, outdoor, and ambient air concentrations for PM/gases.
5.To determine the contribution of ambient concentrations to indoor air/personal exposures for PM/gases.
6.To examine the effects of air shed (location, season), population demographics, and residential setting (apartment vs stand-alone homes) on the relationship between personal exposure and indoor, outdoor, and ambient air concentrations for PM/gases.
Description:
The U.S. EPA National Exposure Research Laboratory (NERL) conducted a longitudinal particulate matter (PM) panel study in Research Triangle Park, NC between June 2000 and June 2001. Participants were selected from two potentially susceptible sub-populations: a multi-racial group of cardiac patients in Chapel Hill, NC and a group of African-Americans with hypertension living in a low/moderate socio-economic status (SES) neighborhood in southeast Raleigh, NC. All 35 participants were over 50 years old, ambulatory, and non-smokers. Participants were sampled for 7 consecutive days during each of four sampling seasons. While the primary focus of the study was on PM exposures, personal, indoor, and ambient gaseous co-pollutants (CO, O3 and NO2) were also sampled. Integrated, 24-hr personal O3 was measured using passive Ogawa badge samplers during the summer, fall, and spring seasons. Ozone was also measured continuously at a central ambient site using the TECO Model 49 analyzer during the summer, fall, winter and spring seasons. Integrated 24-hr NO2 measurements were collected daily inside each participant's home as well as at the ambient monitoring station using Ogawa badges during all four seasons. Real-time CO (1 min avg. time) was measured daily inside each participant's home during all four seasons using the Drager 190 CO monitor. Real-time CO was also collected at the central ambient site using the TECO Model 48 analyzer during all four seasons.
Ambient O3 concentrations were highest during summer and lowest during winter. Ambient O3 concentrations (mean plus/minus std. dev.) were 37.7 plus/minus 22.3 ppb during the summer, 28.9 plus/minus 16.1 ppb during spring, 17.9 plus/minus 15.9 ppb in the fall, and 13.7 plus/minus 10.4 ppb in the winter season. Peak ambient O3 concentrations, however, were similar across all seasons. Personal O3 exposures during summer (3.2 plus/minus 9.3 ppb) and spring (2.2 plus/minus 18.1 ppb) were very similar, but substantially lower than ambient O3 concentrations. No significant differences in personal O3 exposure were observed between cohorts. Data on personal O3 exposures during the fall season were excluded due to high blanks. Overall mean indoor NO2 concentrations were slightly higher in the Raleigh cohort (13.2 plus/minus 14.8 ppb) than the Chapel Hill cohort (7.3 plus/minus 4.4 ppb), likely due to the higher prevalence of gas stoves and furnaces in the Raleigh cohort. Seasonal differences were also observed with highest indoor NO2 concentrations in the winter and lowest concentrations in the summer for both cohorts. Mean ambient NO2 concentrations were as much as three times higher than mean indoor NO2 concentrations. Ambient CO varied seasonally with fall (0.4 plus/minus 0.6 ppm) and winter (0.4 plus/minus 0.6 ppm) concentrations about two times higher than spring (0.2 plus/minus 0.3 ppm) and summer (0.2 plus/minus 0.2 ppm). Generally, there was little temporal variation in indoor CO for both cohorts except for periodic episodes of elevated concentrations. Peak CO concentrations were generally < 20 ppm for each cohort. Further analysis of these data will provide important information on the relationships between gaseous co-pollutants and PM2.5.
This work has been funded wholly by the United States Environmental Protection Agency under contract #68-D-99-012 to the Research Triangle Institute and assistance agreement #CR-828186-01-0 to Shaw University. It has been subjected to Agency review and approved for publication.