Michigan: 83 counties covered
Of 83 rated Michigan counties, 9 are in EPA's highest radon-potential zone (Zone 1) — but every county page links to testing guidance regardless of zone, because a county rating is a county-wide average, not a reading for any one house.
- Wayne County
- Oakland County
- Macomb County
- Kent County
- Genesee County
- Washtenaw County
- Ottawa County
- Ingham County
- Kalamazoo County
- Livingston County
- Saginaw County
- Muskegon County
- St. Clair County
- Jackson County
- Monroe County
- Berrien County
- Calhoun County
- Allegan County
- Eaton County
- Bay County
- Lenawee County
- Grand Traverse County
- Lapeer County
- Midland County
- Clinton County
- Van Buren County
- Montcalm County
- Shiawassee County
- Marquette County
- Ionia County
- Isabella County
- Barry County
- St. Joseph County
- Tuscola County
- Cass County
- Newaygo County
- Branch County
- Hillsdale County
- Mecosta County
- Gratiot County
- Sanilac County
- Houghton County
- Delta County
- Chippewa County
- Wexford County
- Emmet County
- Clare County
- Huron County
- Mason County
- Alpena County
- Oceana County
- Charlevoix County
- Otsego County
- Dickinson County
- Gladwin County
- Cheboygan County
- Manistee County
- Iosco County
- Antrim County
- Roscommon County
- Osceola County
- Menominee County
- Leelanau County
- Ogemaw County
- Kalkaska County
- Benzie County
- Missaukee County
- Arenac County
- Gogebic County
- Crawford County
- Presque Isle County
- Lake County
- Iron County
- Mackinac County
- Alcona County
- Montmorency County
- Alger County
- Oscoda County
- Schoolcraft County
- Baraga County
- Luce County
- Ontonagon County
- Keweenaw County