Vapor Intrusion Testing/Sampling in Buildings
What is Vapor Intrusion?
Vapor intrusion occurs when volatile chemicals lodged in soil or groundwater rise to the surface and are released into the air. This can occur in the open air or into buildings, offices, factories, warehouses, vacant, or abandoned. Vapor intrusion testing/sampling is a method of determining if known or suspected ground contamination is a result in these chemical vapors escaping into the building and are they of such concentration that they can cause short term or long term health effects. If concentrated enough; such as a leak from underground fuel oil, diesel, or gasoline tank; they can be so great that they could result in a fire or explosion. Such fires or explosions are rare-almost always in vacant buildings.
The more common situation is that there are odors in a building that have no identifiable source and tend to be concentrated in the basement or lower levels. Another common situation is that an environmental property assessment (usually referred to as an EPA Phase I Environmental Property Assessment) identifies the potential for soil contamination from a past activity or migration of soil contamination from an adjacent property where spills, leaks, or disposal has occurred.
The vapor intrusion testing/sampling is not complicated. It involves drilling holes into subsurface soil, attaching a sealed sampling line to a vacuum cylinder and allow the soil gases to be drawn into the vacuum cylinder over an extended period of time (usually 8 hours to 24 hours). The sampling is generally performed in a building where there is a suspicion that odors or seepage is coming from beneath the flooring or slab. The results are then compared with available reference levels such as:
- USEPA Vapor Intrusion Screening Levels (VISLS) https://www.epa.gov/vaporintrusion/vapor-intrusion-screening-levels-visls this list identifies approximately 800 chemicals that were detected at some level in an EPA study and whether they pose a vapor intrusion risk.
- Another useful comparison listing is the New Jersey Department of Environmental Protection (NJDEP) Generic Vapor Intrusion Screening Levels. This list identifies screening levels of soil gas for Residential and Non-Residential Properties, as well as Indoor Air Screening levels for Residential and Non-Residential Properties. This listing identifies 47 chemicals detected in soils and has set acceptable safe levels for residences and non-residential properties. www.nj.gov/dep/srp/guidance/vaporintrusion/vig_tables.pdf.
- General information on vapor intrusion from the EPA https://www.epa.gov/vaporintrusion
- “Overview of State Approaches to Vapor Intrusion,” http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.406.7446&rep=rep1&type=pdf.