Vapor intrusion

When soil or groundwater is contaminated, potentially hazardous vapors can migrate into buildings. These volatile organic or inorganic compounds (or both) can impact indoor air quality. This “vapor intrusion” can cause unhealthy levels of hazardous substances in indoor air. We provide guidance to help you investigate vapor intrusion concerns at your cleanup site and determine what to do about it.

Volatile chemicals can migrate from contaminated soil and groundwater into buildings through foundation cracks and utility line openings.

Vapor Intrusion guidance and screening levels

The state's vapor intrusion guidance was developed under Washington's cleanup law, the Model Toxics Control Act (MTCA). It explains how to investigate and manage potential vapor intrusion concerns.