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SOURCE STRENGTHS OF ULTRAFINE AND FINE PARTICLES DUE TO COOKING WITH A GAS STOVE
Citation:
Wallace, L A., C. HowardReed, AND S. J. Emmerich. SOURCE STRENGTHS OF ULTRAFINE AND FINE PARTICLES DUE TO COOKING WITH A GAS STOVE. ENVIRONMENTAL SCIENCE & TECHNOLOGY 38(8):2304-2311, (2004).
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:
Cooking, particularly frying, is an important source of particles indoors. Few studies have measured a full range of particle sizes, including ultrafine particles, produced during cooking. In this study, semicontinuous instruments with fine size discriminating ability were used to calculate particle counts in 124 size bins from 0.01 um to 2.5 um. Data were collected at 5-minute intervals for 18 months in an occupied house. Tracer gas measurements were made every 10 min in each of 10 rooms of the house to establish air change rates. Cooking episodes (N = 44) were selected meeting certain criteria (high concentrations, no concurrent indoor sources, long smooth decay curves) and the number and volume of particles produced was determined for each size category. For each episode, the particle decay rate was determined and used to determine the source strength for each size category. The selected cooking episodes (mostly frying) were capable of producing about 1014 particles over the length of the cooking period (about 15 minutes), more than 90 % of them in the ultrafine (< 0.1 um) range, with an estimated whole-house volume concentration of 50 (um/cm)3. More than 60 % of this volume occurred in the 0.1um to 0.3 um range. Frying produced peak numbers of particles at about 0.06 um, with a secondary peak at 0.01 um. The peak volume occurred at a diameter of about 0.16 um. Since the cooking episodes selected were biased toward higher concentrations, the particle concentrations measured during about 600 hours of morning and evening cooking over a full year were compared to concentrations measured during non-cooking periods at the same times. Cooking was capable of producing more than 10 times the ultrafine particle number observed during non-cooking periods. Levels of PM2.5 were increased during cooking by a factor of 3. Breakfast cooking (mainly heating water for coffee and using an electric toaster) produced concentrations about half those produced from more complex dinnertime cooking. Although the number and volume concentrations observed depend on air change rates, house volume, and deposition rates due to fans and filters, the source strengths calculated here are independent of these variables and may be used to estimate number and volume concentrations in other types of homes with widely varying volumes, ventilation rates and heating and air conditioning practices.
This study was partially funded by an EPA Internal Grant to the corresponding author. It was also supported by the National Institute of Standards and Technology. The paper has been reviewed by both agencies and cleared for publication. Certain commercial equipment, instruments, or materials are identified in this paper in order to specify the experimental procedure adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the materials or equipment identified are necessarily the best available for the purpose.