Vapor Intrusion and Indoor Air Quality

The U.S. Environmental Protection Agency (EPA) describes vapor intrusion as occurring when there is a migration of vapor-forming chemicals from any subsurface source into an overlying building. This subsurface source is often contaminated groundwater or soil.
These vapor-forming chemicals can cause indoor air quality (IAQ) problems and pose a health concern for building occupants. Examples of vapor-forming chemicals listed by EPA include:
• Volatile organic compounds (VOCs), such as trichloroethylene and benzene
• Select semi-volatile organic compounds (SVOCs), such as naphthalene
• Elemental mercury
• Some polychlorinated biphenyls and pesticides
The agency goes on to warn that in extreme cases, the vapors may accumulate in dwellings or occupied buildings to levels that may pose:
• Near-term safety hazards (e.g., explosion)
• Acute health effects
In buildings with lower concentrations of vapor-forming chemicals arising from vapor intrusion, EPA reports the main concern is whether the chemicals may pose an unacceptable risk of health effects due to long-term (i.e., chronic) exposure to these lower levels. They also caution that a complicating factor in evaluating the potential chronic risk from vapor intrusion is the potential presence of some of the same chemicals from emission sources in the building. Examples listed include household solvents, gasoline and cleaners that may pose, separately or in combination with vapor intrusion, a significant human health risk. Fortunately, there are professionals that provide vapor intrusion testing and mitigation services.
These are just a few of the many things to know about vapor intrusion and potential exposure risks. To learn more about this or other indoor air quality, industrial hygiene, environmental, health or safety issues, please visit the websites shown below.
Clark Seif Clark www.csceng.com
EMSL Analytical, Inc. www.emsl.com
LA Testing www.latesting.com
Zimmetry Environmental www.zimmetry.com
CTSI www.ctsiweb.com
Healthy Indoors Magazine www.healthyindoors.com