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Use of a Continuous Nephelometer to Measure Personal Exposure to Particles During the U.S. EPA Baltimore and Fresno Panel Studies

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Abstract: In population exposure studies, personal exposure to particulate matter (PM) is typically measured as a 12- to 24-hour integrated mass concentration. To better understand short-term variation in personal PM exposure, continuous (one-minute averaging time) nephelometers were worn by 15 participants as part of two U.S. Environmental Protection Agency(U.S. EPA) longitudinal PM exposure studies conducted in Baltimore County, Maryland and Fresno, California. Participants also wore inertial impactor samplers (24-hour integrated filter samples) and recorded their daily activities in 15 minute intervals. In Baltimore, the nephelometers correlated well (R2= 0.66) with the PM2.5 impactors. Time-series plots of personal nephelometer data showed each participant's PM exposure to consist of a series of peaks of relatively short duration. Activities corresponding to a significant instrument response included cooking, outdoor activities, transportation, laundry, cleaning, shopping, gardening, moving between microenvironments, and removing/putting on the instrument. On average 63% - 66% of the daily PM exposure occurred indoors at home (about 2/3 of which occurred during waking hours), primarily due to the large amount of time spent in that location (an average of 72% - 77%). Although not a reference method for measuring mass concentration, the nephelometer did help identify PM sources and the relative contribution of those sources to an individual's personal exposure.

The U.S. Environmental Protection Agency through its Office of Research and Development funded and managed the research described here under contract #68-D5-0040 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 an endorsement or recommendation for use.
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Citation:Howardreed, C., A. W. Rea, M. J. Zufall, J. M. Burke, R. W. Williams, J. C. Suggs, L. S. Sheldon, D. B. Walsh, and R. K. Kwok. Use of a Continuous Nephelometer to Measure Personal Exposure to Particles During the U.S. EPA Baltimore and Fresno Panel Studies. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION 50(7):1125-1132, (2000).
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Contact: Liz Hope - (919) 541-2785 or hope.elizabeth@epa.gov
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Division: Human Exposure & Atmospheric Sciences Division
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Branch: Human Exposure Analysis Branch
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Product Type: Journal
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Published: 07/01/2000
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Related Entries:
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Bullet Item Outdoor Vs. Human Exposure: NERL PM Exposure Panel Studies
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Last Updated on Monday, October 22, 2007
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