Site Mitigation & Restoration Program

We protect and maintain California’s land and places
by setting strict standards for land restoration and cleanup

Draft Supplemental Guidance: Screening and Evaluating Vapor Intrusion

The Department of Toxic Substances Control (DTSC), State Water Resources Control Board, and San Francisco Bay Regional Water Quality Control Board have developed supplemental vapor intrusion guidance for conducting vapor intrusion evaluations in California.

The Draft Supplemental Guidance: Screening and Evaluating Vapor Intrusion is available for review and public comment until 12:00 noon, April 30, 2020. See Public Notice (below) for available public meetings.

The Draft Supplemental Guidance provides 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 vapor intrusion attenuation factors
  • Risk management framework for vapor intrusion
  • California-specific vapor intrusion database in Geotracker

New! February 2020 – Draft Supplemental Guidance: Screening and Evaluating Vapor Intrusion

New! Executive Summary Fact Sheet: English / Spanish

New! Public Notice – February 2020 Draft Supplemental Guidance: English / Spanish

Public Information Meetings and Webinar Locations (details in Public Notice)

April 1, 2020 – 1:00PM and 6:00PM
CalEPA Headquarters – Sierra Hearing Room
1001 I Street, Sacramento, CA 95814
This meeting will also be webcast from CalEPA’s Live Webcasts page

April 9, 2020 – 1:00PM and 6:00PM
Online Webinar
Call-In Number: (916) 562-0861; participant passcode: 779621632

April 14, 2020 – 1:00PM and 6:00PM
San Diego Regional Water Quality Control Board, Hearing Room 2375
Northside Drive, Suite 100, San Diego, CA 92108

April 16, 2020 – 1:00PM and 6:00PM
City of Commerce Council Chambers
2535 Commerce Way, Commerce, CA 90040

Public Comments

Comments on the Draft Guidance may be submitted electronically or by mail using one of the Comment Forms provided or by letter. Please see Instructions for information.

Instructions: English / Spanish
Comment Form A (Adobe®): English / Spanish
Comment Form B (Microsoft® Word): English / Spanish

Mail to:
State Water Resources Control Board, Division of Water Quality,
CalEPA VI Workgroup, Attention: Abe Waggoner,
1001 I Street, 15th Floor, Sacramento, CA 95814


Email to:

Vapor Intrusion Fact Sheet

New! Vapor Intrusion and Your Health Fact Sheet (general overview of vapor intrusion): English / Spanish

Vapor Intrusion E-List

Subscribers will receive e-mail notifications regarding news on topics relevant to vapor intrusion—the migration of volatile contaminants through soil and into buildings and potentially causing unacceptable chemical exposure for building occupants. Topics include subsurface investigations and evaluation of potential exposure and human health risk from vapor intrusion.

Subscribe to DTSC Vapor Intrusion E-List.

Vapor Intrusion Guidance Documents

Other Vapor Intrusion Resources