The movement of volatile vapors from contaminated soil or groundwater into overlying indoor spaces. Vapor intrusion can occur when hazardous materials- petroleum products, solvents, dry cleaning constituents- are released to the environment. Impact to soil and groundwater migrates via vapors that are not easily detectable via sight or smell. Vapors can migrate through passages in your floor- openings around pipes, sumps, cracks, or pores in the concrete slab- and compromise indoor air quality. Vapor intrusion is an urgent national issue and knowledge is constantly increasing around it.
Depending on the concentration and types of vapors migrating into a building, a vapor mitigation system may be necessary to protect the health of the occupants. There are two types of mitigation methods: Active or Passive. Passive methods include: sealing cracks, installing barriers, or below-grade venting. Active methods include: installing a sub-slab depressurization system, which mechanically vents vapors outdoors, and implementing structure over-pressurization, which involves adjusting building climate and ventilation to increase the indoor pressure relative to the sub-slab pressure.
VAPOR INTRUSION RESOURCES & INFORMATION
The Michigan Department of Environment, Great Lakes, and Energy (EGLE) and United States Environmental Protection Agency (EPA) have a multitude of PDFs and presentations regarding vapor intrusion: