In its report titled "Overview of EPA’s State and Tribal Indoor Radon Grants Program: A Focus on Activities Conducted During Fiscal Year 2025," the EPA State Indoor Radon Grant Program notes successes in Adoption of State Policies/Regulations or Building Codes.
EPA noted in its report that in FY25, the Michigan Radon program held discussions with the Department of Licensing and Regulatory Affairs Bureau of Construction Codes to discuss revisions to the Michigan Residential Building Code Rule and shared radon testing data with all 83 counties in the state.
The Michigan Indoor Radon Program website explains that "Currently, the Michigan Residential Building Code requires radon-resistant construction techniques in nine Michigan counties: Branch, Calhoun, Cass, Hillsdale, Jackson, Kalamazoo, Lenawee, St. Joseph, and Washtenaw. However, elevated levels of radon have been found in every Michigan county and radon-resistant construction techniques are recommended for all homes statewide."
Sources:
Overview of EPA’s State and Tribal Indoor Radon Grants Program: A Focus on Activities Conducted During Fiscal Year 2025
https://www.epa.gov/system/files/documents/2026-07/sirg-fy25-activities-report.pdf
Michigan Indoor Radon Program
https://www.michigan.gov/egle/about/organization/materials-management/indoor-radon
United States