REISSUE: Public Comment Period for Proposed Volatilization To Indoor Air Pathway Screening Levels

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This notice is being resent to add the 2020 Screening Level Table.

The Department of Environmental, Great Lakes, and Energy Remediation and Redevelopment Division (RRD) developed the 2013 Guidance Document for the Vapor Intrusion Pathway (2013 VI Guidance) to provide information to department staff and their contractors conducting investigations and remedial or corrective actions at sites with potential vapor intrusion issues. The document is available as a technical reference to assist any party conducting activities to address the volatilization to indoor air pathway.

RRD announces a proposed revision to the 2013 VI Guidance, the draft documents are available below. In June 2017 the department rescinded the vapor intrusion screening levels that were included in Appendix D. RRD plans to reinstate residential and nonresidential screening levels and is seeking comment regarding the proposed screening levels.

The department has assisted the regulated community in developing site-specific volatilization to indoor air criteria (SSVIAC) and site-specific target levels (SSTLs) since the screening levels were rescinded. More than 1,600 sets of SSVIAC and SSTLs have been developed during this time. Based on the SSVIAC and SSTLs requests for residential and nonresidential building scenarios and environmental conditions, screening levels have been established that represent conditions consistent with the majority of the requests. The residential scenario represents a home with a basement and the nonresidential scenario represents an average-sized commercial building with slab-on-grade construction (e.g., gas station convenience store). These were the most common scenarios of SSVIAC and SSTLs requests and do not represent the most sensitive of the possible scenarios. The main assumptions for the screening levels are summarized in the Volatilization to Indoor Air Pathway (VIAP) Screening Levels and Site-Specific Criteria Overview (available below). Development details and the screening level tables are included in the proposed Appendix D.1. (available below).

The availability of the screening levels will not affect the ability of a person to develop site-specific criteria or SSTLs under Section 20120b for the department’s review and approval. The availability of the screening levels will not change the validity of any SSVIAC or SSTLs that have been previously provided by RRD. These remain valid for the conditions their development was based on and can still be used.

Once established, these screening levels may be used as site-specific criteria or SSTLs consistent with the guidance provided in the 2013 VI Guidance. The use of the screening levels will require documentation that site conditions match the assumptions used for their development and this documentation will need to be included in submittals to the department. A checklist (available below) for conditions that are not consistent with the development of the screening levels has been drafted to evaluate when site-specific criteria or SSTLs need to be developed. This checklist will also be available to use to document site conditions are appropriate for use of the screening levels and may be included with submittals to the department to receive final approval of the use of screening levels as site-specific criteria or SSTLs.

RRD continues to pursue the development of an on-line calculator that can assist in developing SSVIAC or SSTLs for scenarios where the screening levels do not apply, or where site conditions can be modified to produce more representative site-specific criteria or SSTLs. Until the calculator is available, the department will continue to assist in developing site-specific criteria or SSTLs for this pathway. Requests for assistance in their development may be made using the questionnaire available below. Alternatively, a person may develop site-specific criteria or SSTLs using any of the options available in Section 20120b and submit the necessary information to the department for review and approval.

RRD will accept comments regarding the proposed screening levels for 30 days. Comments should be submitted to with a reference to the 2020 VIAP Screening Levels in the subject line, no later than July 2, 2020.

For questions regarding the proposed screening levels, please contact Dr. Shane Morrison, RRD Toxicologist, at, or Patty Brandt, RRD Program Specialist at  Please do not reply to this email.