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FIELD COMPARISONS OF DUAL SMPS-APS SYSTEMS TO MEASURE INDOOR-OUTDOOR PARTICLE SIZE DISTRIBUTIONS
Citation:
Vette, A F., T. M. Peters, AND L S. Sheldon. FIELD COMPARISONS OF DUAL SMPS-APS SYSTEMS TO MEASURE INDOOR-OUTDOOR PARTICLE SIZE DISTRIBUTIONS. Presented at ISEA 2000 Exposure Analysis in the 21st Century: Integrating Science, Policy and Quality of Life, Monterey Peninsula, CA, October 24-27, 2000.
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:
Simultaneous measurements of particle size distributions across multiple locations can provide critical information to accurately assess human exposure to particles. These data are very useful to describe indoor-outdoor particle relationships, outdoor particle penetration through a building shell and even spatial variations in particle size distribution across distances of several kilometers. To simultaneously measure particle size distributions at different locations, methodologies with demonstrated comparability are required to ensure data quality prior to field deployment. In this study, we compared two Scanning Mobility Particle Sizers (SMPS) and two Aerosol Particle Sizers (APS). The SMPS measures particles from 0.01 - 0.6 ?m and the APS measures particles from 0.7 ?m up to 10 ?m when using a PM10 inlet. In this study we examined size distributions from 0.01 - 2.5 ?m. Laboratory and field audits were conducted using an aerosol generator to produce a polydisperse aerosol of a sodium chloride solution and a monodisperse aerosol of polystyrene latex (PSL) spheres with known particle size. Instrument audits consistently showed agreement within 15%, on average, across the measured particle size range (0.01 - 2.5 ?m). Field comparisons were conducted indoors and outdoors of a seldom occupied, but furnished residence. The purpose of the field comparisons was to determine the utility of using two individual SMPS-APS systems to measure indoor-outdoor particle size distributions. In addition, one of the systems located indoors was used to alternately sample indoor and outdoor air through a controlled ball-valve switching manifold. This enabled a simultaneous comparison of a common aerosol measured by the two systems. The results from the field study showed poor agreement between the two SMPS-APS systems and point to the need for improvements in the audit system to produce aerosol concentrations in the range of those encountered in the field.
This work has been funded in part by the United States Environmental Protection Agency 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 endorsement or recommendation for use.