Superfund Research Program
Indoor Air Concentration Dynamics and Vapor Intrusion
Project Leader: Eric M. Suuberg
Grant Number: P42ES013660
Funding Period: 2009-2021
The Indoor Air Concentration Dynamics and Vapor Intrusion Project has been developing an advanced mathematical modeling tool that describes the phenomenon of vapor intrusion (VI). VI involves evaporation from groundwater of volatile contaminants (e.g., chlorinated solvents, petroleum compounds). Field investigation of VI is expensive as well as alarming to those whose homes are targeted. There is an incentive to correctly identify where site investigation, is necessary, and to define a robust investigational strategy. Recent evidence of fluctuations in residential indoor air contaminant concentrations, combined with new toxicological data, have raised a host of concerns in the regulatory community on how to be properly protective. The mathematical model developed in this program is beginning to yield results that reduce the level of uncertainty in investigation. The model has led the way to development of a new spreadsheet screening tool for both chlorinated and petroleum contaminated sites which can realistically predict significant indoor air impacts. The modeling also led to a conclusion that the US EPA guidance on vapor intrusion is unnecessarily conservative in a key screening factor. The model also shows that large fluctuations in indoor air concentrations are a result of a confluence of particular circumstances that are not necessarily characteristic of many VI situations.
The Indoor Air Concentration Dynamics and Vapor Intrusion Project is also studying removal of poly and perfluoroalkyl substances (PFASs) from drinking water, using sorption to granular activated carbon. PFASs often co-occur in groundwater with the chlorinated solvents relevant to this project’s focus on organic contaminants of VI concern in groundwater. The factors defining useful carbons are being systematically assessed.