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Publications | August 14, 2017
2 minute read

New Standards for Indoor Air Pollution

DEQ, DHHS Target Properties for Investigation and Possible Evacuation

On August 7, the Michigan Department of Environmental Quality (MDEQ) disseminated a list of interim "screening levels" for protection against certain types of indoor air pollution.  

The screening levels were developed jointly by the MDEQ and the Michigan Department of Health and Human Services (MDHHS). They apply to 31 volatile chemical compounds and prescribe numeric values for indoor air, soil vapor, ground water and soil. The chemicals in the list include some that are considered to present health risks for short-term exposure. The screening levels include values which, if exceeded, can result in mandatory evacuation of affected buildings. While the MDHHS has statutory authority to evacuate buildings where it finds an "imminent danger," the MDEQ does not have this authority.

Intrusion of vapors from contaminated soil and groundwater into buildings has become an increasing focus at Brownfield and environmental remediation sites. In 2013, the MDEQ established its first formal guidance regarding vapor intrusion. Earlier this summer the MDEQ revoked the 2013 guidance in anticipation of the August 7 release. These new screening levels are the latest phase in the MDEQ's efforts to address potential risks from indoor air pollution due to underlying soil or groundwater contamination. Of particular concern are certain industrial solvents and dry-cleaning fluids that are known to cause cancer and other health effects at elevated levels.

The MDEQ, in partnership with the MDHHS, is aggressively looking for properties that may pose vapor intrusion risks. The MDEQ is actively reviewing past filings by property owners, including Baseline Environmental Assessments and Due Care Plans, to identify properties for vapor intrusion evaluation. They are also reviewing past cleanup sites where vapor intrusion was not historically evaluated. Even though the new screening levels are not legally binding, the MDEQ and MDHHS have initiated building evacuations based on other unpromulgated standards for vapor evaluation.

The attorneys in the Warner Norcross Resource, Energy and Environmental Practice Group are prepared to advise property owners responsible for remediation or due care at existing sites and buyers, sellers and secured parties of properties with potential vapor intrusion issues. For further information, please contact Scott Hubbard at or any other member of the Resources, Energy and Environment Practice Group.