Vapor Intrusion


Toxic vapors in indoor air can come from multiple sources – underground contamination, consumer products or outdoor air. Vapors can travel between soil particles and reach ground surface.

The Department of Toxic Substances Control (DTSC), the State Water Board, and the San Francisco Bay Regional Water Quality Control Board (SF Bay Regional Water Board) are currently developing a supplemental vapor intrusion guidance document for conducting uniform vapor intrusion evaluations in California. This guidance document, when finalized, will serve as a supplement to existing guidance (see below). The new guidance will provide detailed information on the following topics:

  • Soil gas, subslab, indoor air, and outdoor air sampling recommendations that are focused on understanding spatial and temporal variability
  • Recommendations for use of USEPA 2015 attenuation factors
  • Risk management framework for vapor intrusion
  • California-specific vapor intrusion database

Existing Guidance Documents:

*This is not the complete list of existing vapor intrusion guidance documents.

California Vapor Intrusion GeoTracker Database
Guidance on Uploading Vapor Data into GeoTracker

Guidance on Uploading Vapor Data into GeoTracker

This document provides instruction on how to input relevant vapor intrusion information used in a vapor intrusion assessment into the GeoTracker database.

GeoTracker Resources

ESI Login

ESI Information Page

GeoTracker Help Desk
State Water Resources Control Board

What is Vapor Intrusion?

When some chemicals are spilled or dumped, they can form vapors that travel through the soil, reach under buildings, and contaminate the indoor air. Vapors can reach the indoor air through cracks in foundations, utility pipes, and sewer lines.

What is Trichloroethylene?

Trichloroethylene is commonly used in industries to remove oil or grease. It’s also in some household products such as stain removers and adhesives.

Where Can I Find More Vapor Intrusion Information?

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  • Coming Soon - Public Notice 2019 Draft Supplemental Guidance: Screening and Evaluating Vapor Intrusion
  • Coming Soon – Public Workshop Dates and Locations
  • Coming Soon – 2019 Public  Draft Supplemental Guidance: Screening and Evaluating Vapor Intrusion
  • Coming Soon – Executive Summary Draft 2019 Supplemental Guidance Fact Sheet
  • Coming Soon - Vapor Intrusion and Your Health Fact Sheet
  • Coming Soon - Trichloroethylene (TCE) in Indoor Air Fact Sheet


If you have any questions about vapor intrusion, please email us at:

Or contact:
State Water Board

Tina Ures
Engineering Geologist
Phone: (916) 341-5749