When soil or groundwater is contaminated, potentially hazardous vapors may migrate into buildings. These volatile organic or inorganic compounds (or both) can potentially impact indoor air quality.
Here you'll find guidance that helps you investigate vapor intrusion concerns at your cleanup site and determine what to do about it. We've also linked to an important update: 2015 changes in toxicity values and screening levels. You'll find links to Environmental Protection Agency guidance, too.
Our state's vapor intrusion guidance was developed under Washington's cleanup law, the Model Toxics Control Act (MTCA).
This figure shows volatile chemicals migrating from contaminated soil and groundwater plumes into buildings. Chemicals are entering through cracks in the foundation and openings for utility lines. Atmospheric conditions and building ventilation are influencing vapor intrusion. Source: Environmental Protection Agency's vapor intrusion webpage, accessed October 2017.