Volatilization to Indoor Air - Recommended Interim Action Screening Levels (RIASLs), Time Sensitive Recommended Interim Action Screening Levels (TS-RIASLs)

The Michigan Department of Environment, Great Lakes, and Energy (EGLE) and the Michigan Department of Health and Human Services (MDHHS) collaboratively developed recommended interim action screening levels for indoor air. The indoor air screening levels were developed using the best available toxicological and scientific information.

The current list includes indoor air screening levels for 29 chemicals with the potential to cause adverse human health effects for short-term exposures or to require expedited response activities.  Additional chemicals are being evaluated and added as required on a project-specific basis. 

The screening levels are not promulgated rules and cannot be used for a facility determination, compliance, or for obtaining closure of a release.  The indoor air screening levels are to be used to assist with risk evaluation by: 1) determining if potentially unsafe levels of chemicals are present in the indoor air; 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.

Media-specific screening levels (MSSLs) for soil, groundwater, and soil vapor have also been generated for the 29 chemicals to evaluate risk and interim response actions. The media-specific screening levels are based on the indoor air screening levels identified in the TSG Report and were developed using conservative assumptions.  Typically, an exceedance of a time-sensitive screening level in any media will warrant expedited investigation and possible mitigation.

For a copy of the Toxic Steering Group Report, the RIASLs, the TS-RIASLs, and/or the MSSLs, please contact Shane Morrison at 517-284-5063 or morissons5@michigan.gov.  For questions regarding the use of the screening levels for vapor intrusion, please contact the Volatilization to Indoor Air Pathway TAPS point of contact in your local District office in the Remediation and Redevelopment Division.