261597 Mapping spatial and temporal variability of community exposure to PCE from vapor intrusion

Monday, October 29, 2012

Jill Johnston , Department of Environmental Sciences and Engineering, University of North Carolina - Chapel Hill, Chapel Hill, NC
The migration of subsurface contaminants into indoor air is a potential health threat at thousands of sites across the country. As more information is collected about vapor intrusion, the exposure is characterized by spatial and temporal heterogeneity within a site. It is difficult to predict and assess exposure at a community level. This study attempted to examine short-term temporal fluctuations in concentrations of chlorinated organic compounds in the indoor air of residential homes due to vapor intrusion in an environmental justice community. Using a community-based participatory design, we collected 72-hour samples for tetrachloroethylene (PCE) using sorbent packed passive diffusion samplers. Samples were collected over 10 days in 20 homes throughout the community that sit atop the contaminated shallow groundwater plume in southwest San Antonio, Texas. Any potential confounding indoor sources were removed. Indoor air samples were analyzed using gas chromatography/ mass spectrometry instrumentation, following EPA Method TO-17 procedures. Preliminary results demonstrate significant variability across both space and time. The data set will be analyzed for correlations with barometric pressure, temperature differentials and wind speed using longitudinal statistical analysis techniques. Results will also be compared with a house-level predictive model previously developed. Passive sampling technique coupled with community partnerships provides a less intrusive and more cooperative approach to data collection and show particular value in environmental justice settings. This study contributes to the body evidence on exposure screening and variability to estimate the occurrence of vapor intrusion in a home. This information will be used to update a probabilistic-based community exposure map and model to predict and screen for indoor air contamination as a result of subsurface contaminant migration.

Learning Areas:
Environmental health sciences

Learning Objectives:
Demonstrate community-based techniques to assess the vapor intrusion potential in an environmental justice setting Describe the significance of meteorological and household characteristics on explaining spatial and temporal variability of vapor intrusion

Keywords: Environmental Exposures, Environmental Justice

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I an a doctoral candidate in the Department of Environemental Sciences and Engineering at UNC-Chapel Hill. I am the recipient of an NSF Graduate Research Fellowship and co-principal investigator on modelling and assessing the vapor intrusion pathway at contaminated sites.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.