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.
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.