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PARTICLE SIZE DISTRIBUTIONS FROM SELECT RESIDENCES PARTICIPATING IN THE NERL RTP PM PANEL STUDY
Citation:
Vette, A F., R W. Williams, M Riediker, AND J. Thornburg. PARTICLE SIZE DISTRIBUTIONS FROM SELECT RESIDENCES PARTICIPATING IN 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:
Particle Size Distributions from Select Residences Participating in the NERL RTP PM Panel Study. Alan Vette, Ronald Williams, and Michael Riediker, U.S. Environmental Protection Agency, National Exposure Research Laboratory, Research Triangle Park, NC 27711; Jonathan Thornburg, Research Triangle Institute, Research Triangle Park, NC 27709.
Particle size distributions were measured indoors and outdoors of four residences during the Research Triangle Park (RTP) Particulate Matter (PM) Panel Study sponsored by the U.S. EPA National Exposure Research Laboratory (NERL). The objective of this research was to assess the factors affecting particle concentrations in the indoor environment, including characterizing indoor sources of PM and infiltration of PM originating outdoors. Size resolved particle number concentrations were measured using a Scanning Mobility Particle Spectrometer (SMPS; TSI Model 3936) and an Aerodynamic Particle Sizer (APS; TSI Model 3320). Indoor and outdoor aerosol concentrations were alternately measured through a ball-valve switching manifold. Concurrent measurements of indoor air exchange rates were made continuously by releasing sulfur hexafluoride and monitoring concentration decay using a portable gas chromatograph (Lagus Applied Technologies).
Data were collected from four homes in an environmental justice area in southeast Raleigh, NC over multiple seasons. Monitoring took place during fall 2000 (1 home), winter 2001 (4 homes), and spring 2001 (3 homes). Although the houses were located within 5 km of each other, they varied considerably in size (between one and two story; 1000 - 2500 square feet), construction (brick or wood siding) and age (24 - 42 years).
Results from all of the houses show that infiltration of ambient particles between 0.1 and 1 micrometer was the predominate source of indoor particles with periodic episodes of elevated particle concentrations due to cooking. In general, indoor/outdoor particle concentration ratios were highest for particles between 0.1 and 1 micrometer during non-source periods. Average indoor/outdoor ratios in this size region varied considerably from about 0.5 to 0.9, both between homes and within the same home during different seasons. Cooking sources included frying and baking, which generated particles primarily in the ultrafine size range (<0.1 micrometer). Hourly air exchange rates varied between homes and seasons, and generally ranged from about 0.5/h to 3/h.
This work has been funded wholly or in part by the United States Environmental Protection Agency 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.