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REAL-TIME PERSONAL NEPHELOMETER AND TIME ACTIVITY DATA FROM THE NERL RTP PM PANEL STUDY
Citation:
Rea, A W., R W. Williams, B. Rodes, M. Hermann, AND J. Thornburg. REAL-TIME PERSONAL NEPHELOMETER AND TIME ACTIVITY DATA FROM THE NERL RTP PM PANEL STUDY. Presented at 11th Annual Meeting of the International Society of Exposure Analysis, Charleston, SC, November 4-8, 2001.
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:
A longitudinal particulate matter (PM) exposure study was conducted in the Research Triangle Park, NC, area between June 2000 and June 2001. Participants were selected from two groups of potentially susceptible sub-populations: a group of African-Americans living in an environmental justice area in southeast Raleigh, and a group of cardiac patients with implanted cardiac defibrillators in Chapel Hill, NC. All of the participants were over 50 years old, ambulatory, and non-smokers. Approximately 35 participants were sampled for 7 consecutive days during each of 4 sampling seasons (~28 days total for each participant). Personal and indoor monitoring included continuous (1 min. avg. time) nephelometer measurements (personal DataRAM, MIE Inc.). Detailed time activity information (15 min time resolution), follow up questionnaire data on exposure to particle sources, and residential information were also collected.
The nephelometer data were displayed daily in the field for participants to view. Details on the activities corresponding to PM exposure peaks measured by the nephelometers were recorded in the field. Analysis of time activity patterns indicates that participants from both cohorts spent similar amounts of time in the six microenvironments examined during both the summer and fall seasons. (Winter and spring data are unavailable at this time, but will be presented.) Participants from both cohorts spent >70% of their time inside at home, ~10% of their time both inside away from home and at work, and ~5% of their time outside at home or outside away from home and in transit. PM exposure for each cohort was similar in most cases. During the summertime, the nephelometer mass for being outside at home was ~10 times higher for the African American cohort than during the fall season. The time activity data show that this is due to frequent mowing, grilling, and other particle generating outdoor activities. Nephelometer mass recorded while participants were inside away from home was ~10 times higher in the summertime for the Cardiac cohort than in the fall. This was due to elevated PM exposure while in restaurants either due to cooking or nearby smokers. Other activities that contributed to personal PM exposure included spraying aerosols (air fresheners, cleaners, or hair spray), cleaning cat litter boxes, burning wood in a fireplace, burning trash outside, outdoor grilling, and automobile/diesel exhaust.
This work has been funded wholly or in part by the US EPA under Contract No. 68-D99-012 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.