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Environ Sci Technol

Title:		Screening houses for vapor intrusion risks: a multiple regression analysis approach
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, USA. jillj@unc.edu"
Journal Title:		Environ Sci Technol
Year:		2013
Volume:		20130523
Issue:		11
Page Number:		5595 - 5602
DOI:		10.1021/es4003795
ISSN/ISBN:		1520-5851 (Electronic) 0013-936X (Linking)
Abstract:		"The migration of chlorinated volatile organic compounds from groundwater to indoor air-known as vapor intrusion-can be an important exposure pathway at hazardous waste sites. Because sampling indoor air at every potentially affected home is often logistically infeasible, screening tools are needed to help identify at-risk homes. Currently, the U.S. Environmental Protection Agency (EPA) uses a simple screening approach that employs a generic vapor 'attenuation factor,' the ratio of the indoor air pollutant concentration to the pollutant concentration in the soil gas directly above the groundwater table. At every potentially affected home above contaminated groundwater, the EPA assumes the vapor attenuation factor is less than 1/1000--that is, that the indoor air concentration will not exceed 1/1000 times the soil-gas concentration immediately above groundwater. This paper reports on a screening-level model that improves on the EPA approach by considering environmental, contaminant, and household characteristics. The model is based on an analysis of the EPA's vapor intrusion database, which contains almost 2,400 indoor air and corresponding subsurface concentration samples collected in 15 states. We use the site data to develop a multilevel regression model for predicting the vapor attenuation factor. We find that the attenuation factor varies significantly with soil type, depth to groundwater, season, household foundation type, and contaminant molecular weight. The resulting model decreases the rate of false negatives compared to EPA's screening approach"
Keywords:		"Air Pollution, Indoor/*analysis Databases, Factual Family Characteristics Housing *Models, Theoretical Regression Analysis Seasons Soil Pollutants/*analysis United States United States Environmental Protection Agency Volatile Organic Compounds/analysis Wa;"
Notes:		"MedlineJohnston, Jill E Gibson, Jacqueline MacDonald eng Research Support, U.S. Gov't, Non-P.H.S. 2013/05/11 Environ Sci Technol. 2013 Jun 4; 47(11):5595-602. doi: 10.1021/es4003795. Epub 2013 May 23"