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DETERMINATION OF PARTICLE DEPOSITION RATES FOR COOKING AND OTHER INDOOR SOURCE
Citation:
HowardReed, C, L A. Wallace, AND S. J. Emmerich. DETERMINATION OF PARTICLE DEPOSITION RATES FOR COOKING AND OTHER INDOOR SOURCE. Presented at 19th Annual AAAR Conference, St. Louis, MO, November 6-10, 2000.
Impact/Purpose:
The main objective is to investigate human exposure to fine and coarse particles (and PAHs) from several important sources such as cooking, woodsmoke, and household cleaning. A second objective is to investigate the observed increased personal exposure (compared to indoor air concentrations measured by a fixed monitor) to particles: the so-called "personal cloud," that has been observed in many occupational and some environmental studies. A third objective is to incorporate the findings into a mass-balance indoor air quality model.
Description:
Residential indoor particle concentrations are dependent on indoor sources, penetration of outdoor particles, air change with outdoors, and deposition of particles on indoor surfaces as well as other loss mechanisms. Of these factors, few data are available on deposition of particles generated indoors (e.g., from cooking or cleaning sources). To increase the knowledge base related to the deposition of particles of indoor origin, a one-year continuous particle and air change rate monitoring study was completed in an occupied home in Reston, VA.
Indoor concentrations or particles, ranging in size from 0.01 um to 20 um, were continuously measured with several "real-time" instruments, including: a Scanning Mobility Particle Sizer (SMPS; TSI, Inc.), an Aerodynamic Particle Sizer (APS; TSI, Inc.), and an Aethalometer (Magee Scientific). Particle concentrations were also measured in multiple locations within the house using other continuous instruments: 2 to 4 Climets (Climet Instruments), 2 to 4 personal DataRams (MIE, Inc.), and two PAH monitors (Ecochem, Inc.). To determine air change rates, a gas chromatograph with electron capture detector (GC/ECD) was used to measure the decay of SF6 in multiple locations within the house.
Sources that contributed the largest number of particles in this non-smoking home were combustion activities (e.g., candles, matches, incense), cooking activities (e.g., frying, sauteeing, broiling, and stir-frying), and cleaning activities (e.g., changing cat's litter box). During these events, indoor particle concentrations for all size categories measured (depending on source) increased to levels significantly higher (one to three orders of magnitude) than those measured outdoors. As a result, particle deposition rates may be directly solved with a mass balance model. Particle deposition rates tended to follow the theoretical "U-shaped" curve for increasing particle size. Initial estimates of deposition rates range from 3.5 h-1 to 0.4 h-1 for particles from 0.01 um to 0.5 um and 0.4 h-1 to 5 h-1 for particles from 0.5 um to 7 um. Using measured deposition rates for multiple particle sizes and associated theoretical deposition velocities, effective contact surface area to volume ratios for this house will also be calculated. The results from this study have the potential to improve modeling of indoor air particles.
The research described in this abstract has been funded wholly or in part by the United States Environmental Protection Agency. 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.