The Vapor Intrusion documents address investigating and evaluating the vapor intrusion pathway, including data evaluation and mitigation approaches.
The Brownfields documents provide overviews of vapor intrusion issues; incentives and tools used to accelerate the cleanup and reuse of Brownfield and BRAC sites; and the various available systems and programs that track, monitor, and/or inform about land use controls.
Petroleum vapor intrusion (PVI) is a subset of vapor intrusion (VI) and is the process by which volatile petroleum hydrocarbons (PHCs) released as vapors from light nonaqueous phase liquids (LNAPL), petroleum-contaminated soils, or petroleum-contaminated groundwater migrate through the vadose zone and into overlying buildings. Fortunately, in the case of PHC vapors, this migration is often limited by microorganisms that are normally present in soil. The organisms consume these chemicals, reducing them to nontoxic end products through the process of biodegradation. The extent and rate to which this natural biodegradation process occurs is strongly influenced by the concentration of the vapor source, the distance the vapors must travel through soil from the source to potential receptors, and the presence of oxygen (O2) in the subsurface environment between the source and potential receptors.