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.


Proposed Vapor Intrusion Assessment Amendment to State Water Board Resolution 92-49

Public Scoping Meetings

The State Water Resources Control Board (State Water Board) proposes to amend State Water Board Resolution No. 92-49 to include requirements for the investigation and assessment of vapor intrusion from vapor- forming chemicals. Vapor intrusion is a frequent problem at contaminated sites statewide. If left uncontrolled, chemical vapors can pose a significant health risk to communities living on and near contaminated sites. Vapor migration from the subsurface into buildings is complex which can cause an underestimation of vapor concentrations indoors. To control or prevent vapor migration into existing buildings or for future development, sites must first be assessed or screened for vapor intrusion risk.

Currently, vapor intrusion assessments are conducted on a case-by-case basis, using applicable guidance as appropriate. The proposed amendment to State Water Board Resolution No. 92-49 would establish state policy for water quality control that requires the use of an expeditious, consistent, and protective approach using statewide data for assessing vapor intrusion risk.

Virtual public scoping meetings were held on Thursday, April 28, 2022, from 10:00am -12:00m and 5:00pm-7:00pm.

Public Notice
The State Water Board, Division of Water Quality, Site Cleanup Unit staff will hold two separate virtual public scoping meetings with the same presentation for a proposed amendment to State Water Board Resolution No. 92-49 (as amended on April 21, 1994, and October 2, 1996) to include requirements for the investigation and assessment of vapor intrusion at cleanup sites statewide. The meetings will provide an overview of the proposed elements of the draft amendment and an opportunity for the public to provide oral and written comments to be considered for inclusion into the draft resolution presented to the State Water Board Members for adoption at a later time and for the development of a Substitute Environmental Document.  A formal public comment period and public hearing will also be held before the State Water Board Members regarding the draft amendment at a later date.

Public Comments
The CEQA scoping meeting will be conducted virtually, using online video and audio broadcast software. The State Water Board will accept both written and oral comments. Agencies, organizations, and the public will be able to provide oral comments directly through the online zoom meeting or zoom telephone access number. Please register in advance to access the zoom meeting online or by telephone.

Written comments must be received by 12:00 p.m. PDT (noon) on May 9, 2022.

How to Submit Written Comments:

  1. Mail:
    Jeanine Townsend, Clerk to the Board
    State Water Resources Control Board
    P.O. Box 100, Sacramento, CA 95812-2000 (mail)
    1001 I Street, 15th floor, Sacramento, CA 95814 (hand-delivered)

    Couriers delivering hand copies of comment letters must check in with lobby security personnel, who can contact Jeanine Townsend at (916) 341-5620.

  2. Email: (if less than 15 megabytes in total size)
    (Please include the subject “Comment Letter – Resolution 92-49 Amendment Scoping”)

Future Notices
Any change in the date, time, and place of the scoping meetings will be publicly noticed on the State Water Board website and through Lyris e-mail list. Any person desiring to receive future notices concerning the proposed vapor intrusion amendment should sign up on the Lyris e-mail list. To sign up for a Lyris list, access the email List Subscription Form at:, click the “Water Quality” tab, and check the box for “Vapor Intrusion.” 

Vapor Intrusion Information

Feb 2020 Draft Supplemental Guidance

February 2020 Draft Supplemental Guidance

The Public 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 for available public meetings.

Executive Summary Fact Sheet

Executive Summary Fact Sheet

The Executive Summary Fact Sheet highlights the topics suggested and briefly describes the four recommended steps for screening and evaluating vapor intrusion.

Hard Copy Locations

***Due to the COVID-19 public health emergency, access to hard copies are currently not available.

CalEPA Building
1001 I Street, Sacramento, CA
Contact Abe Waggoner, (916) 341-5895

North Coast Regional Water Board Office
5550 Skylane Building, Suite A, Santa Rosa, CA
Contact: Paul Nelson, (707) 576-2686

Central Valley Regional Water Board Office
1685 E. Street, Fresno, CA
Contact: Christine Hernandez, (559) 445-6542

San Francisco Bay Regional Water Board Office
1515 Clay Street, #1400, Oakland, CA
Contact: Melinda Wong, (510) 622-2430

Lahontan Regional Water Board Office (South Lake Tahoe)
2501 Lake Tahoe Blvd., South Lake Tahoe, CA
Contact: Jeff Brooks, (530) 542-5420

Lahontan Regional Water Board Office (Victorville)
15095 Amargosa Road, Bldg. 2, Suite 210, Victorville, CA
Contact: Alonzo Poach, (760) 241-7365

Los Angeles Regional Water Board Office
320 W. 4th Street, Suite 200, Los Angeles, CA
Contact: Lucinda (Cindy) Flores, (213) 576-6633

Santa Ana Regional Water Board Office
3737 Main Street, Suite 500, Riverside, CA
Contact: Lenore Gamez, (951) 782-4905

San Diego Regional Water Board Office
2375 Northside Drive, Suite 100, San Diego, CA
Contact: Records Request Hotline, (619) 516-1990

Department of Toxic Substances Control Regional Office
5796 Corporate Avenue, Cypress, CA
Contact: Jone Barrio, (714) 484-5336

Department of Toxic Substances Control Regional Office
9211 Oakdale Avenue, Chatsworth, CA
Contact: Robert Hardison, (818) 717-6521

May 2020 Agenda

The CalEPA Vapor Intrusion Workgroup has developed and posted video presentations online and will host two live Question and Answer Sessions in lieu of the public meetings.

April 2020 Agenda

Due to the COVID-19 public health emergency, the original public information meetings scheduled for April 2020 are postponed until further notice.

Public Comment due 12:00 noon, June 1, 2020

Written comments on February 2020 Public Draft Supplemental Guidance must be submitted by 12:00 noon, June 1, 2020 by mail or email.

Methods to Submit Comments

See Comment Submission Instructions for details.

To help the CAlEPA Vapor Intrusion Workgroup to organize comments, please use one of the designated comment forms and electronically submit your comments to the email provided below. The work group offers Comment Form A (Adobe® Version) and Comment Form B (Microsoft® Word Version). Alternatively, you may also submit your comments in a letter (or email) drafted in the official format of your agency or company, or in a format of your choosing.

Below are the available methods (use one):

How to Submit Comments:

  1. Email:
    (please add “Comment Submittal” to subject line)
  2. Mail: State Water Resources Control Board, Division of Water Quality
    CalEPA VI Workgroup, Attention: Abe Waggoner
    1001 I Street, 15th Floor, Sacramento, CA 95814


Please refer to Comment Submission Instructions or contact Abe Waggoner at or (916) 341-5895.

Note on Response to Comment

Please Note: The Vapor Intrusion Work Group will group and categorize comments and prepare responses. Responses to individual comments will not be provided.

What are vapor-forming chemicals?

Vapor-forming chemicals can easily move into the air and form vapors. Common ones include solvents used in dry cleaning, degreasing, gasoline and diesel fuel. Examples of toxic vapor-forming chemicals are:

  • Tetrachloroethylene, also called perchloroethylene (“perc” or PCE): PCE is known to the State of California to cause cancer. Many dry cleaners have used PCE for decades, but this use will be phased out by 2023.
  • Trichloroethylene (TCE): TCE is known to the State of California to cause cancer and harm reproductive health. TCE is commonly used in industries to remove oil or grease. It’s also in some household products such as stain removers and adhesives.
  • Naphthalene: Naphthalene is known to the State of California to cause cancer. Sources include inks, dyes, fossil fuels, mothballs, tar, tobacco smoke, and burning of wood.

What are other sources of vapor-forming chemicals?

Many consumer products, such as household cleaners, furniture, adhesives and paints, contain these chemicals and can pollute indoor air. Vapor-forming chemicals in outdoor air can also enter buildings.

Vapor Intrusion and Your Health Fact Sheet

Guidance on Uploading Vapor Data into GeoTracker

The Vapor Intrusion and Your Health Fact Sheet is a general overview about vapor intrusion.

California Vapor Intrusion GeoTracker Database

Vapor Intrusion is a complex, highly variable science. A robust empirical dataset is needed to help us better understand vapor behavior.

GeoTracker Database

Tutorial Video on Uploading Vapor Data Into GeoTracker

Vapor Data Video Thumbnail This video is a tutorial on how to navigate and input vapor intrusion related information into GeoTracker Electronic Submittal of Information Portal. The video provides background on the vapor intrusion database, how to upload field point data and create building profiles, as well as how to navigate in the portal to upload tools related to vapor intrusion information.

State Water Board YouTube Website:

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.

ESI Login

ESI Information Page

GeoTracker Help Desk

State Water Resources Control Board

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