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PM CONCENTRATIONS ASSOCIATED WITH PERSONAL ACTIVITIES BASED ON REAL-TIME PERSONAL NEPHELOMETRY DATA FROM THE NERL RTP PM PANEL STUDY
Citation:
Rea, A W., C Croghan, J. Thornburg, B. Rodes, AND R W. Williams. PM CONCENTRATIONS ASSOCIATED WITH PERSONAL ACTIVITIES BASED ON REAL-TIME PERSONAL NEPHELOMETRY DATA FROM THE NERL RTP PM PANEL STUDY. Presented at International Society of Exposure 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:
A longitudinal particulate matter (PM) exposure study sponsored by EPA's National Exposure Research Laboratory (NERL) 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 with hypertension living in a low/moderate socio-economic status (SES) neighborhood in southeast Raleigh, and a multi-racial 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. A total of 35 participants were sampled for 7 consecutive days during each of 4 sampling seasons (~28 days total for each participant). Detailed time activity information (15 min intervals) and continuous personal and indoor nephelometry (personal DataRAM, MIE Inc.) data were collected. The data from the nephelometers are interpreted semi-quantitatively in this analysis. The nephelometry data were averaged over 15 min consecutive time intervals and matched with the associated time activity diary. Individuals who had more than 10% of their PM mass associated with exposure to ETS (46 person-days) were removed from this analysis.
Personal PM peaks elevated above ambient levels were identified in the nephelometry data and matched with the activities as described by participants on their time activity diaries or personal recall. For participants that slept at continuously night or did not have any elevated nighttime PM exposures, the average of the nighttime PM concentration was used as a baseline PM exposure (n=798 person-days). People with elevated PM concentrations due to nighttime activities were removed from the database (n=19 person-days). Peaks were identified during daytime activities and the baseline PM exposure was subtracted from this value for each individual on each day. Our preliminary analysis has identified 370 peaks. Results indicate that mean personal concentrations due to cooking were 291 plus/minus 614 ug/m3 (n=178; range 1 - 5580 ug/m3) while mean cleaning concentrations were 274 plus/minue 1338 ug/m3 (n=64; range 2 - 10,757 ug/m3). PM concentrations from personal grooming activities such as dressing, using hair spray, spray deodorant, etc. were 555 plus/minus 2848 ug/m3 (n=55; range 1 -21,181 ug/m3). PM exposures outside the home were also identified. Mean concentrations while traveling were 142 plus/minus 265 ug/m3 (n=58; range 1 - 1669ug/m3). Mean concentrations while inside at stores and restaurants were 152 plus/minus 372 ug/m3 (n=20; range 9 - 1682 ug/m3). Although the PM data are semi-quantitative, this analysis gives some insight into the relative exposures due to short duration activities (typically ranging from 15 to 45 min in duration) that cannot be identified using 24 hr average integrated PM mass measurements.
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.