Vapor intrusion is the migration of volatile chemicals from the subsurface into overlying
buildings. Volatile chemicals in contaminated soil or groundwater can emit vapors that may
migrate through soil and into indoor air spaces.
This website includes general information on vapor intrusion, along with information on some of the
efforts being conducted in support of the Environmental Protection Agency’s (EPA’s) developing Vapor
EPA’s Vapor Intrusion (VI) Database is designed to hold data to support site-specific measurements
of vapor attenuation, or the reduction in vapor concentrations as volatile contaminants move from
soil and groundwater into indoor air. High-quality, representative, and reproducible measurements of
soil gas, groundwater, and indoor air contaminant concentrations from VI sites are needed to measure
vapor attenuation, verify that VI model predictions are accurate, improve understanding of the
operating physical phenomena of VI, and help EPA, states, and other practitioners evaluate and
improve predictive models and screening algorithms for the VI pathway. In March 2008, EPA released
an improved and updated version of the EPA VI database that was originally developed in support of
the 2002 VI Guidance. Documentation of this update, and how it differs from the 2002 database, can
(or by clicking on "Other Documents" on the left of this page). To access the updated data, please
login, which will enable you to access the “Database Downloads” section of this website.
This website also includes presentations and supporting materials for several workshops conducted by
EPA in support of the developing guidance. These presentations can be accessed by clicking on the
“Workshops and Conferences” link on the left of this page.
Disclaimer: This is a development site for public use and in
support of Agency activities. It is not an official US EPA website. It is operated by RTI
International, who is under contract to the US EPA for developing and maintaining an indoor air
vapor intrusion database, along with other activities to improve EPA's Vapor Intrusion