Radon in Michigan

About 3 in 10 homes tested in Michigan were at or above the EPA action level of 4 pCi/L.

47%27%26%

82,449 homes tested, 2008–2017

Below 2 pCi/L: 47%
2 to 4 pCi/L: 27%
4 pCi/L or more: 26%

The line marks the EPA action level, 4 pCi/L.

The EPA puts 9 of Michigan's 83 counties in Zone 1, its highest radon category, 32 in Zone 2 and 42 in Zone 3.

Every county in Michigan

Sorted by the share of homes tested at or above 4 pCi/L. Select a county for local details and costs.

County	Homes tested	At or above 4	Median	EPA zone
Lenawee County		57%	4.6 pCi/L	1
Branch County		55%	4.4 pCi/L	1
Hillsdale County		55%	4.4 pCi/L	1
Jackson County		50%	3.9 pCi/L	1
Livingston County		43%	3.4 pCi/L	2
Washtenaw County		41%	3.2 pCi/L	1
Dickinson County		39%	3.1 pCi/L	2
Clinton County		39%	3.1 pCi/L	2
Otsego County		38%	3.2 pCi/L	2
Ionia County		37%	2.9 pCi/L	2
Calhoun County		36%	3.0 pCi/L	1
Iron County		36%	2.6 pCi/L	2
Tuscola County		36%	2.6 pCi/L	3
Eaton County		34%	2.8 pCi/L	2
St. Joseph County		34%	2.9 pCi/L	1
Lapeer County		33%	2.7 pCi/L	2
Kalamazoo County		33%	2.8 pCi/L	1
Shiawassee County		32%	2.5 pCi/L	2
Barry County		31%	2.6 pCi/L	2
Cass County		30%	2.6 pCi/L	1
Monroe County		30%	2.5 pCi/L	2
Oakland County		29%	2.3 pCi/L	2
Huron County		27%	1.9 pCi/L	3
Ingham County		25%	2.2 pCi/L	2
Berrien County		24%	2.0 pCi/L	3
Montcalm County		24%	2.1 pCi/L	2
Marquette County		23%	2.0 pCi/L	2
Presque Isle County		23%	1.9 pCi/L	2
Keweenaw County		23%	0.9 pCi/L	2
Genesee County		22%	2.0 pCi/L	2
Mecosta County		22%	2.0 pCi/L	3
Delta County		22%	1.7 pCi/L	3
Alcona County		21%	1.7 pCi/L	2
Mackinac County		20%	1.2 pCi/L	3
Oscoda County		19%	2.1 pCi/L	3
Allegan County		18%	1.7 pCi/L	3
Van Buren County		18%	1.9 pCi/L	3
Wayne County		18%	1.8 pCi/L	3
Saginaw County		17%	1.7 pCi/L	3
Gratiot County		17%	1.7 pCi/L	3
Ottawa County		17%	1.6 pCi/L	3
Sanilac County		17%	1.6 pCi/L	2
Kent County		17%	1.8 pCi/L	2
Manistee County		17%	1.6 pCi/L	3
Alger County		16%	1.2 pCi/L	2
Isabella County		16%	1.6 pCi/L	3
Gladwin County		15%	1.3 pCi/L	3
Emmet County		15%	1.6 pCi/L	2
Schoolcraft County		15%	0.6 pCi/L	3
Ogemaw County		15%	2.0 pCi/L	3
Lake County		15%	1.4 pCi/L	3
Missaukee County		15%	1.6 pCi/L	3
Montmorency County		15%	1.6 pCi/L	2
Clare County		14%	1.6 pCi/L	3
St. Clair County		14%	1.5 pCi/L	3
Macomb County		13%	1.6 pCi/L	3
Alpena County		13%	0.9 pCi/L	2
Gogebic County		13%	1.2 pCi/L	2
Kalkaska County		13%	1.3 pCi/L	3
Roscommon County		13%	1.0 pCi/L	3
Antrim County		12%	1.5 pCi/L	2
Menominee County		12%	1.2 pCi/L	2
Chippewa County		12%	0.9 pCi/L	3
Grand Traverse County		12%	1.4 pCi/L	3
Ontonagon County		11%	1.3 pCi/L	3
Baraga County		11%	1.1 pCi/L	2
Houghton County		11%	1.1 pCi/L	2
Osceola County		11%	1.7 pCi/L	3
Charlevoix County		10%	1.4 pCi/L	2
Wexford County		10%	1.5 pCi/L	3
Arenac County		9%	0.7 pCi/L	3
Benzie County		9%	1.3 pCi/L	3
Bay County		9%	1.4 pCi/L	3
Cheboygan County		8%	0.8 pCi/L	3
Newaygo County		8%	1.3 pCi/L	3
Iosco County		8%	0.7 pCi/L	3
Leelanau County		8%	1.2 pCi/L	2
Mason County		6%	1.1 pCi/L	3
Crawford County		6%	1.3 pCi/L	3
Oceana County		6%	1.2 pCi/L	3
Midland County		5%	1.0 pCi/L	3
Luce County	19 tests	–	–	3
Muskegon County		3%	1.2 pCi/L	3

"–" means fewer than 20 tests or no lab data, too few for a reliable figure.

Sources

EPA Map of Radon Zones (public domain).
CDC Environmental Public Health Tracking Network, radon tests from labs, 2008–2017. Pre-mitigation tests only.

Last updated October 2026. How we calculate these numbers.