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REAL-TIME INDOOR AND OUTDOOR MEASUREMENTS OF BLACK CARBON IN AN OCCUPIED HOUSE: AN EXAMINATION OF SOURCES
Citation:
LaRosa, L., T J. Buckley, AND L A. Wallace. REAL-TIME INDOOR AND OUTDOOR MEASUREMENTS OF BLACK CARBON IN AN OCCUPIED HOUSE: AN EXAMINATION OF SOURCES. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION 52(1):41-49, (2002).
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:
Black carbon (BC) was measured every five minutes for two years (May, 1998 to May 2000) inside and immediately outside a northern Virginia house (suburban Washington, DC) occupied by two nonsmokers. Two Aethalometers TM, which measure BC by optical transmission through a quartz fiber tape, were employed indoors and outdoors. Meteorological parameters were obtained on an hourly basis from the nearby Dulles airport. Indoor activities were recorded to identify indoor sources such as combustion activities, which occurred 9% of the time during the first year and 4% of the time during the second year. At times without indoor sources, indoor/outdoor BC ratios averaged 0.52 in the first year and 0.35 in the second year. The main outdoor source of BC was the general regional background, contributing 83-84% of the total during each of the two years. Morning rush-hour traffic contributed 8-9% of the total. An evening peak in the fall and winter, thought to include contributions from woodburning, was responsible for about 8% of the annual average BC concentration. The main indoor sources of BC were cooking and candle burning, contributing 16% and 31% of the annual average indoor concentrations in the two years. Relative humidity (RH) affected the outdoor Aethalometer TM in both years. An artifact associated with the tape advance was noted for the Aethalometer TM, but a correction factor was developed that reduced the associated error by a factor of 2.
This research was partially funded by the Environmental Protection Agency. This paper has been reviewed and approved for publication. However, the paper does not necessarily reflect the policy of the EPA. Use of brand names does not imply endorsement.