2021 Media-Specific Volatilization to Indoor Air
Interim Action Screening Levels
The Department of Environmental, Great Lakes, and Energy (EGLE) Remediation and Redevelopment Division (RRD) has updated the 2013 Guidance Document for the Vapor Intrusion Pathway (2013 VI Guidance) by replacing the previously rescinded Appendix D.3 – Acute Exposures Immediate Response Activity Screening Levels (IRASLs) with Media Specific Volatilization to Indoor Air Interim Action Screening Levels (MSSLs) that have been updated following the December 2020 Toxics Steering Group Report. The references to IRASLs (Immediate Response Action Screening Levels) that remain throughout the 2013 VI Guidance should be interpreted to reference the MSSLs.
The 2013 VI Guidance provides 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 person conducting activities to address the volatilization to indoor air pathway.
The MSSLs for soil, shallow groundwater, groundwater, and soil vapor are based on the recommended interim action screening levels identified in the Toxics Steering Group (TSG) Report which provides the toxicological and background information for each hazardous substance. The MSSLs were developed using the best available approaches by incorporating equations and inputs that account for conditions that frequently occur across the state (e.g., shallow groundwater).
The MSSLs are not intended for compliance or for obtaining closure of a release. These interim action screening levels are intended to assist with risk evaluation by 1) determining if potentially unsafe levels of chemicals are present in the environmental media; 2) determining whether interim action to reduce potential exposure is needed; and 3) if interim action is needed, assist in determining how quickly those actions should be completed.
For questions regarding the development and/or use of media specific volatilization to indoor air interim action screening levels, please contact Dr. Shane Morrison, Remediation and Redevelopment Division Toxicologist, at MorrisonS5@Michigan.gov.
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