What Is Vapor Intrusion?

vapor intrusionVapor intrusion is when chemical vapors from contaminated soil or groundwater enter a building.  The majority of the time these chemicals come from commercial or industrial activities such as dry cleaners or petroleum spills or releases.  These chemicals contain volatile organic compounds (VOC).  When soil and groundwater is contaminated, the VOCs evaporate.  In cases of vapor intrusion, the VOC’s evaporate into a structure above instead of safely into the outside air.  These vapors can enter a building through cracks in the foundation slab or through utility lines or floor-wall cracks of a basement.  Special equipment is required to test for VOC’s as they are usually colorless and odorless.


If a contaminated site is undergoing cleanup near your home or business, the party responsible for the clean-up may request permission to investigate for vapor intrusion on your property.  If potentially harmful vapors are identified in the building, a vapor mitigation system can be installed.  This sub-slab depressurization system captures the vapors below the foundation and vents them outside the building.  These systems are also used to prevent radon from entering a residence.  Additional testing may be required after the system is installed to ensure it is operating properly.  These systems will be utilized as long as the threat of vapor intrusion exists.  In some cases where the contaminant source is eliminated, the mitigation system is no longer needed.


If you have questions or would like assistance investigating potential vapor intrusion issues on your property please contact Bay Environmental Strategies, Inc. at 1 800-576-2476.