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Vapor Intrusion

Vapor intrusion occurs when gases or vapors from chemicals and petroleum products migrate into occupied buildings. It may be harmful for individuals to breathe indoor air that contains the vapors of these chemicals inside such buildings.

Vapor intrusion is now a standard consideration during investigations related to the Resource Conservation and Recovery Act (RCRA); Underground Storage Tanks (UST); and the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA/Superfund). 

Q: What types of homes does vapor intrusion affect?
A: Vapor intrusion can affect any type of home.

Q: What health concerns are related to vapor intrusion?
A: The health risks associated with vapor intrusion vary based on the type of chemicals, the levels of the chemical found, the length of exposure and the health of the exposed individuals. At high concentrations some temporary symptoms may include eye and respiratory irritation, headaches and nausea. Over many years, low-level exposures to certain chemicals may raise the lifetime risk of some cancers or chronic diseases.

Q: How does EPA test for vapor intrusion?
A: EPA uses several testing methods, either separately or in combination with one another. Soil and ground water samples near a contaminated site are used to evaluate whether or not there is the potential for vapor intrusion.  Further tests take place where vapor intrusion appears to be a possibility. Summa canisters can be used to collect samples of ambient (outdoor) air, indoor air or air from beneath the foundation of a building. Tests of the air underneath foundations are called subslab samples.EPA’s Trace Atmospheric Gas Analyzer (TAGA) Mobile Laboratory can also be used to evaluate ambient, subslab, and in-home samples on-site.

Q: What solutions are available?
A: The most common solution is to install a mitigation system, which helps prevent vapors from entering homes. Since they are similar to radon mitigation systems, these systems provide the added benefit of preventing radon from entering the home as well.  In addition, any cracks in the building foundation should be sealed to help prevent vapors from entering the home.

Q: What contaminants do vapor intrusion sites have?
A: Some of the typical organic compounds found at vapor intrusion sites include Tetrachloroethylene (PCE), Trichloroethylene (TCE), 1,1-Dichloroethane, 1,1-Dichloroethylene (1,1-DCE), 1,2-Dichloroethane (1,2-DCA), Chloroethene (vinyl chloride)

Additional information about these chemicals and other volatile organic compounds (VOCs) can be found in EPA’s Health Effects Notebook of Hazardous Air Pollutants and the Agency for Toxic Substances and Disease Registry’s (ATSDR) ToxFAQs.


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