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Environ Sci Technol

Title:		"Probabilistic approach to estimating indoor air concentrations of chlorinated volatile organic compounds from contaminated groundwater: a case study in San Antonio, Texas"
Author(s):		Johnston JE; Gibson JM;
Address:		"Department of Environmental Sciences & Engineering, Gillings School of Global Public Health, University of North Carolina-Chapel Hill, CB 7431 Chapel Hill, North Carolina 27599, United States. jillj@unc.edu"
Journal Title:		Environ Sci Technol
Year:		2011
Volume:		20101216
Issue:		3
Page Number:		1007 - 1013
DOI:		10.1021/es102099h
ISSN/ISBN:		1520-5851 (Electronic) 0013-936X (Linking)
Abstract:		"This paper describes a probabilistic model, based on the Johnson-Ettinger algorithm, developed to characterize the current and historic exposure to tricholorethylene (TCE) and tetrachlorethylene (PCE) in indoor air from plumes of groundwater contamination emanating from the former Kelly Air Force Base in San Antonio, Texas. We estimate indoor air concentration, house by house, in 30 101 homes and compare the estimated concentrations with measured values in a small subset of homes. We also compare two versions of the Johnson-Ettinger model: one used by the Environmental Protection Agency (EPA) and another based on an alternative parametrization. The modeled mean predicted PCE concentration historically exceeded PCE screening levels (0.41 ug/m(3)) in 5.5% of houses, and the 95th percentile of the predicted concentration exceeded screening levels in 85.3% of houses. For TCE, the mean concentration exceeded the screening level (0.25 ug/m(3)) in 49% of homes, and the 95th percentile of the predicted concentration exceeded the screening level in 99% of homes. The EPA model predicts slightly lower indoor concentrations than the alternative parametrization. Comparison with measured samples suggests both models, with the inputs selected, underestimate indoor concentrations and that the 95th percentiles of the predicted concentrations are closer to measured concentrations than predicted mean values"
Keywords:		"Air Pollution, Indoor/*analysis/statistics & numerical data Environmental Monitoring/methods Fresh Water/chemistry *Models, Statistical Tetrachloroethylene/*analysis Texas Trichloroethylene/*analysis Uncertainty Volatile Organic Compounds/*analysis Water;"
Notes:		"MedlineJohnston, Jill E Gibson, Jacqueline MacDonald eng 2010/12/18 Environ Sci Technol. 2011 Feb 1; 45(3):1007-13. doi: 10.1021/es102099h. Epub 2010 Dec 16"