Radon in Michigan: radon map by county
EPA's Map of Radon Zones puts 9 of Michigan's 83 counties in Zone 1 (predicted average indoor radon above 4 pCi/L), 32 in Zone 2 and 42 in Zone 3. Of 82,449 building tests that radon laboratories reported for 2008 to 2017, 26.3% were at or above EPA's 4 pCi/L action level, against 36.5% nationally (number 24 of 42 states with 1,000+ tests). The highest county share is Lenawee County (56.7% of 1,349 tests).
Radon by county in Michigan
| County | EPA zone | Lab tests | Median | 4+ pCi/L |
|---|---|---|---|---|
| Alcona County | Zone 2 | 128 | 1.7 | 20.5% |
| Alger County | Zone 2 | 118 | 1.2 | 16.4% |
| Allegan County | Zone 3 | 592 | 1.7 | 18.4% |
| Alpena County | Zone 2 | 727 | 0.9 | 13.3% |
| Antrim County | Zone 2 | 232 | 1.5 | 12% |
| Arenac County | Zone 3 | 62 | 0.7 | 8.9% |
| Baraga County | Zone 2 | 116 | 1.1 | 11% |
| Barry County | Zone 2 | 1,078 | 2.6 | 30.7% |
| Bay County | Zone 3 | 501 | 1.4 | 8.5% |
| Benzie County | Zone 3 | 222 | 1.3 | 8.7% |
| Berrien County | Zone 3 | 1,030 | 2.0 | 24.2% |
| Branch County | Zone 1 | 586 | 4.4 | 55.4% |
| Calhoun County | Zone 1 | 1,235 | 3.0 | 36.4% |
| Cass County | Zone 1 | 449 | 2.6 | 30.4% |
| Charlevoix County | Zone 2 | 368 | 1.4 | 9.8% |
| Cheboygan County | Zone 3 | 349 | 0.8 | 8% |
| Chippewa County | Zone 3 | 222 | 0.9 | 11.6% |
| Clare County | Zone 3 | 154 | 1.6 | 14.1% |
| Clinton County | Zone 2 | 1,466 | 3.1 | 38.5% |
| Crawford County | Zone 3 | 143 | 1.3 | 6.2% |
| Delta County | Zone 3 | 417 | 1.7 | 21.5% |
| Dickinson County | Zone 2 | 446 | 3.1 | 39.3% |
| Eaton County | Zone 2 | 2,180 | 2.8 | 34.4% |
| Emmet County | Zone 2 | 528 | 1.6 | 15.2% |
| Genesee County | Zone 2 | 1,355 | 2.0 | 21.9% |
| Gladwin County | Zone 3 | 187 | 1.3 | 15.4% |
| Gogebic County | Zone 2 | 127 | 1.2 | 12.9% |
| Grand Traverse County | Zone 3 | 932 | 1.4 | 11.5% |
| Gratiot County | Zone 3 | 327 | 1.7 | 16.8% |
| Hillsdale County | Zone 1 | 1,177 | 4.4 | 54.8% |
| Houghton County | Zone 2 | 680 | 1.1 | 10.8% |
| Huron County | Zone 3 | 196 | 1.9 | 26.5% |
| Ingham County | Zone 2 | 2,399 | 2.2 | 24.9% |
| Ionia County | Zone 2 | 899 | 2.9 | 36.8% |
| Iosco County | Zone 3 | 107 | 0.7 | 7.7% |
| Iron County | Zone 2 | 172 | 2.6 | 36.2% |
| Isabella County | Zone 3 | 568 | 1.6 | 16.4% |
| Jackson County | Zone 1 | 1,989 | 3.9 | 49.7% |
| Kalamazoo County | Zone 1 | 3,261 | 2.8 | 33.3% |
| Kalkaska County | Zone 3 | 157 | 1.3 | 12.7% |
| Kent County | Zone 2 | 6,257 | 1.8 | 16.5% |
| Keweenaw County | Zone 2 | 24 | 0.9 | 22.7% |
| Lake County | Zone 3 | 76 | 1.4 | 14.9% |
| Lapeer County | Zone 2 | 479 | 2.7 | 33.4% |
| Leelanau County | Zone 2 | 387 | 1.2 | 7.7% |
| Lenawee County | Zone 1 | 1,349 | 4.6 | 56.7% |
| Livingston County | Zone 2 | 3,306 | 3.4 | 43.1% |
| Luce County | Zone 3 | 19 | 1.0 | 4.2% |
| Mackinac County | Zone 3 | 66 | 1.2 | 19.8% |
| Macomb County | Zone 3 | 4,659 | 1.6 | 13.4% |
| Manistee County | Zone 3 | 286 | 1.6 | 16.5% |
| Marquette County | Zone 2 | 686 | 2.0 | 23.4% |
| Mason County | Zone 3 | 348 | 1.1 | 6.3% |
| Mecosta County | Zone 3 | 408 | 2.0 | 21.7% |
| Menominee County | Zone 2 | 77 | 1.2 | 11.7% |
| Midland County | Zone 3 | 1,430 | 1.0 | 5.3% |
| Missaukee County | Zone 3 | 237 | 1.6 | 14.9% |
| Monroe County | Zone 2 | 1,065 | 2.5 | 30.4% |
| Montcalm County | Zone 2 | 407 | 2.1 | 23.6% |
| Montmorency County | Zone 2 | 156 | 1.6 | 14.7% |
| Muskegon County | Zone 3 | 536 | 1.2 | 3.2% |
| Newaygo County | Zone 3 | 331 | 1.3 | 7.9% |
| Oakland County | Zone 2 | 12,288 | 2.3 | 28.8% |
| Oceana County | Zone 3 | 270 | 1.2 | 5.9% |
| Ogemaw County | Zone 3 | 81 | 2.0 | 15% |
| Ontonagon County | Zone 3 | 87 | 1.3 | 11.4% |
| Osceola County | Zone 3 | 189 | 1.7 | 10.6% |
| Oscoda County | Zone 3 | 40 | 2.1 | 18.5% |
| Otsego County | Zone 2 | 598 | 3.2 | 38.2% |
| Ottawa County | Zone 3 | 1,957 | 1.6 | 16.8% |
| Presque Isle County | Zone 2 | 321 | 1.9 | 22.8% |
| Roscommon County | Zone 3 | 132 | 1.0 | 12.7% |
| Saginaw County | Zone 3 | 2,213 | 1.7 | 17% |
| Sanilac County | Zone 2 | 264 | 1.6 | 16.6% |
| Schoolcraft County | Zone 3 | 52 | 0.6 | 15.2% |
| Shiawassee County | Zone 2 | 1,021 | 2.5 | 31.6% |
| St. Clair County | Zone 3 | 515 | 1.5 | 13.7% |
| St. Joseph County | Zone 1 | 652 | 2.9 | 34.1% |
| Tuscola County | Zone 3 | 267 | 2.6 | 35.5% |
| Van Buren County | Zone 3 | 335 | 1.9 | 18% |
| Washtenaw County | Zone 1 | 5,668 | 3.2 | 41.3% |
| Wayne County | Zone 3 | 4,582 | 1.8 | 17.5% |
| Wexford County | Zone 3 | 446 | 1.5 | 9.7% |
Lab tests: buildings tested by radon laboratories, 2008 to 2017; median in pCi/L; “4+ pCi/L” is the share of tests at or above EPA's action level. n/a: no value on file (no tests, or too few to report).
What the zones mean
Zone 1 counties have a predicted average indoor radon screening level above 4 pCi/L, Zone 2 from 2 to 4 pCi/L and Zone 3 below 2 pCi/L. The prediction is from 1993 indoor measurements, geology, aerial radioactivity, soils and foundation types. EPA: “This map should not be used to determine if individual homes need to be tested.” EPA recommends fixing a home at 4 pCi/L or more and considering a fix between 2 and 4 pCi/L, because there is no known safe level of exposure.
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Radon in Michigan: questions
What radon zone is Michigan?
EPA's 1993 map does not give states one zone; it zones each county. In Michigan, 9 counties are Zone 1, 32 Zone 2 and 42 Zone 3. EPA says the map "should not be used to determine if individual homes need to be tested".
Which Michigan counties have the highest radon levels?
By the share of laboratory tests at or above 4 pCi/L for 2008 to 2017 (counties with 20 or more tests): Lenawee County 56.7% (median 4.6 pCi/L, 1,349 tests); Branch County 55.4% (median 4.4 pCi/L, 586 tests); Hillsdale County 54.8% (median 4.4 pCi/L, 1,177 tests); Jackson County 49.7% (median 3.9 pCi/L, 1,989 tests); Livingston County 43.1% (median 3.4 pCi/L, 3,306 tests).
How common is high radon in Michigan?
26.3% of the 82,449 tests in the laboratory data for Michigan (2008 to 2017) were at or above 4 pCi/L; the national share was 36.5%. Buildings are tested by choice, often because of a sale or a concern, so the share describes the tests on file, not every home.
Should I test for radon in Michigan?
Yes. EPA recommends testing every home no matter where it is, fixing it at 4 pCi/L or more and considering a fix between 2 and 4 pCi/L, because there is no known safe level of radon exposure.
States bordering Michigan
Other free hazard lookups
- Radon by county and ZIP codeEPA radon zone and the radon test results on file for any county, ZIP code or address.
- Fault lines near an addressUSGS-mapped earthquake faults within 5 miles, their age and slip rate, and the USGS seismic hazard value.
- Power lines near an addressHigh-voltage transmission lines within 1 mile from federal maps, with voltage and distance.
- Flood zone lookupThe FEMA flood zone mapped at any US address. Not an official flood zone determination.
- Superfund sites near an addressThe nearest EPA Superfund (NPL) sites and their status.
All of these, plus wetlands, FEMA hazard ratings and the federal contamination lists, are in the Environmental Records Report for any US address ($29).
Superfund sites in Michigan · Radon map of every state
Data compiled 2026-10-20. County-level screening information, not a radon measurement of any building.