Radon zones in Iowa
Last updated
EPA’s Map of Radon Zones places 99 Iowa counties in its three radon potential zones: 99 in Zone 1 (highest), 0 in Zone 2 (moderate), and 0 in Zone 3 (low).
What this means for Iowa homes
Most Iowa counties fall in Zone 1. EPA predicts average indoor screening levels above 4 pCi/L across much of Iowa, so elevated radon is common. Testing is especially worthwhile here, and radon-resistant construction features make sense for new homes.
EPA’s guidance is the same everywhere: test your home, fix it if the level is 4 pCi/L or higher, and consider fixing between 2 and 4 pCi/L. The zone map is from 1993 and should not be used to decide whether a single home needs testing.
Iowa radon program
EPA lists the following state contact for Iowa: Iowa Department of Health and Human Services, phone 515-281-4928. Website: idph.iowa.gov/radon. State programs can tell you about local testing data, free or discounted test kits, disclosure rules for home sales, and credentialed radon professionals.
Iowa counties and their EPA radon zones
| County | EPA radon zone |
|---|---|
| Adair County | Zone 1 |
| Adams County | Zone 1 |
| Allamakee County | Zone 1 |
| Appanoose County | Zone 1 |
| Audubon County | Zone 1 |
| Benton County | Zone 1 |
| Black Hawk County | Zone 1 |
| Boone County | Zone 1 |
| Bremer County | Zone 1 |
| Buchanan County | Zone 1 |
| Buena Vista County | Zone 1 |
| Butler County | Zone 1 |
| Calhoun County | Zone 1 |
| Carroll County | Zone 1 |
| Cass County | Zone 1 |
| Cedar County | Zone 1 |
| Cerro Gordo County | Zone 1 |
| Cherokee County | Zone 1 |
| Chickasaw County | Zone 1 |
| Clarke County | Zone 1 |
| Clay County | Zone 1 |
| Clayton County | Zone 1 |
| Clinton County | Zone 1 |
| Crawford County | Zone 1 |
| Dallas County | Zone 1 |
| Davis County | Zone 1 |
| Decatur County | Zone 1 |
| Delaware County | Zone 1 |
| Des Moines County | Zone 1 |
| Dickinson County | Zone 1 |
| Dubuque County | Zone 1 |
| Emmet County | Zone 1 |
| Fayette County | Zone 1 |
| Floyd County | Zone 1 |
| Franklin County | Zone 1 |
| Fremont County | Zone 1 |
| Greene County | Zone 1 |
| Grundy County | Zone 1 |
| Guthrie County | Zone 1 |
| Hamilton County | Zone 1 |
| Hancock County | Zone 1 |
| Hardin County | Zone 1 |
| Harrison County | Zone 1 |
| Henry County | Zone 1 |
| Howard County | Zone 1 |
| Humboldt County | Zone 1 |
| Ida County | Zone 1 |
| Iowa County | Zone 1 |
| Jackson County | Zone 1 |
| Jasper County | Zone 1 |
| Jefferson County | Zone 1 |
| Johnson County | Zone 1 |
| Jones County | Zone 1 |
| Keokuk County | Zone 1 |
| Kossuth County | Zone 1 |
| Lee County | Zone 1 |
| Linn County | Zone 1 |
| Louisa County | Zone 1 |
| Lucas County | Zone 1 |
| Lyon County | Zone 1 |
| Madison County | Zone 1 |
| Mahaska County | Zone 1 |
| Marion County | Zone 1 |
| Marshall County | Zone 1 |
| Mills County | Zone 1 |
| Mitchell County | Zone 1 |
| Monona County | Zone 1 |
| Monroe County | Zone 1 |
| Montgomery County | Zone 1 |
| Muscatine County | Zone 1 |
| O'Brien County | Zone 1 |
| Osceola County | Zone 1 |
| Page County | Zone 1 |
| Palo Alto County | Zone 1 |
| Plymouth County | Zone 1 |
| Pocahontas County | Zone 1 |
| Polk County | Zone 1 |
| Pottawattamie County | Zone 1 |
| Poweshiek County | Zone 1 |
| Ringgold County | Zone 1 |
| Sac County | Zone 1 |
| Scott County | Zone 1 |
| Shelby County | Zone 1 |
| Sioux County | Zone 1 |
| Story County | Zone 1 |
| Tama County | Zone 1 |
| Taylor County | Zone 1 |
| Union County | Zone 1 |
| Van Buren County | Zone 1 |
| Wapello County | Zone 1 |
| Warren County | Zone 1 |
| Washington County | Zone 1 |
| Wayne County | Zone 1 |
| Webster County | Zone 1 |
| Winnebago County | Zone 1 |
| Winneshiek County | Zone 1 |
| Woodbury County | Zone 1 |
| Worth County | Zone 1 |
| Wright County | Zone 1 |
County names follow the 2020 Census. Zones from the EPA Map of Radon Zones (text version). Rows marked “zone of” use the zone EPA gave the predecessor or surrounding county.
Next steps: read how to test your home, check a result with the level calculator, or look up a single address by ZIP code.