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How vapor intrusion happens

A home with vapors seeping into the basement from the surrounding ground
Environment, Great Lakes, and Energy

How vapor intrusion happens

Vapor intrusion sometimes occurs where chemicals were spilled, leaked, or dumped and not cleaned up. For example, properties such as gas stations, dry cleaners, or businesses operating metal parts degreasers use chemicals like gasoline or solvents that can cause vapor intrusion.

If these chemicals are mishandled and get into the ground, they can move through the soil and groundwater. Although the chemicals are often released as liquid, they easily evaporate, becoming a vapor in the air that you often cannot see or smell.

Vapor intrusion happens by way of a complex path. View the diagram or scroll to read different portions of the pathway.

Vapors can slip through cracks in the foundation and/or gaps where pipes enter the basement.

Chemicals can get into groundwater and be spread by its natural flow.

Underground vapors sometimes move along sandy soil surrounding pipes.

Sand or gravel around foundations can make it easier for vapors to pass through.