CAREER: Vapor Intrusion, Knowledge Brokers and Environmental Health - A Three-Dimensional Perspective

The average person in the U.S. spends 90% of their time indoors (Klepeis et al., 2001) where concentrations of pollutants are typically higher than outdoor concentrations (Zhang et al., 1994). Consequently, indoor air polution is extremely important in terms of a person's overall environmental health. There are many sources of indoor air pollution, but one that is too often overlooked is the transport of subsurface vapors into indoor air spaces (i.e. vapor intrusion). In the 1970s, vapor intrusion of radon gas captured the attention of the environmental health community. The vapor intrusion of radon, which is naturally occurring in the subsurface across much of the United States, as well as countries across the globe, is the 2nd leading cause of lung cancer in the United States (NCI, 2014). More recently, vapor intrusion of volatile organic compounds (VOCs) that emanate from hazardous waste sites have been gaining attention due adverse health effects (McAlary et al., 2009). It is estimated that one quarter of all hazardous waste sites in the United States have conditions that could result in vapor intrusion exposures (Colbert et al., 2008). A "solution" for radon vapor intrusion was obtained quickly because policy decisions were based on affordability, rather than health-protective standards. However, VOC vapor intrusion requires more scientific inquiry because assessing health risks at very low health-protective levels for poses significant challenges. USEPA recommends collecting extensive data sets (USEPA 2012a). The data includes information that is not well-understood and little to no guidance exists to aid in the interpretation of the results (Johnson et al., 2014; Lutes et al., 2014). Consequently, VOC vapor intrusion site assessment data is becoming plagued by "big data" issues and regulators are being buried in un-interpreted (or misinterpreted) data, while health risks remain unprotected. The intellectual merit of this NSF CAREER proposal is that for the first time a vapor intrusion model will to collectively consider atmospheric, indoor and subsurface domains, in an effort to address unexplained preliminary field data collected by the PI. Based on the PI's field data set, as well as some recent reports in the literature (Holton, 2013), current vapor intrusion models are extremely limited in their ability to describe field observations. This project will directly respond to this limitation. The PI and her collaborators have already developed and published fairly extensively on a subsurface vapor intrusion model (Pennell et al., 2009; Bozkurt et al., 2009; Bozkurt, 2009; Pennell and Suuberg, 2010; Yao et al., 2011); however, field observations strongly suggest that without systematic evaluation of fate and transport processes within all the three relevant domains (atmospheric, indoor and subsurface), accurate assessment of vapor intrusion exposure risks is not possible.