Iowa Radon Data
Iowa Radon Levels by County
Every county in Iowa is an EPA Radon Zone 1 county. Use the table to find your county, see its zone, and get to a local radon resource. Radon varies home to home, so testing your own home is the only way to know your level.
All 99 Iowa counties are EPA Radon Zone 1, the highest-risk category. Iowa averages about 8.5 pCi/L of indoor radon versus a US average near 1.3 pCi/L, and roughly 71.6% of Iowa homes test at or above the 4 pCi/L action level, the highest share of any state.
Iowa counties, all EPA Radon Zone 1
Source: EPA
Iowa average indoor radon (pCi/L)
Source: Iowa HHS
of Iowa homes at or above 4 pCi/L
Source: Iowa Radon Survey
A note on county averages
We publish only figures we can attribute to a primary source. The EPA Radon Zone (1 for every Iowa county) is official. A single official average for each individual county is not published by the EPA or Iowa HHS, and the county or zip-code averages shown on many radon directory sites are user-submitted estimates rather than authoritative data. Where a county average is not backed by a primary Iowa HHS or Iowa Radon Survey figure, the table reads "Not published" instead of a number we cannot stand behind. Because radon varies house to house, radon testing of your own home is the only accurate measure. If a test comes back at or above the EPA action level of 4.0 pCi/L, a radon mitigation system is what brings the level down, and what that costs in Iowa is set by the foundation type rather than by the county reading.
All 99 Iowa Counties
Sort by county or zone. Filter to find yours.
| Avg indoor radon (pCi/L) | Local resource | ||
|---|---|---|---|
| Adair County | Zone 1 | Not published | Get a quote |
| Adams County | Zone 1 | Not published | Get a quote |
| Allamakee County | Zone 1 | Not published | Get a quote |
| Appanoose County | Zone 1 | Not published | Get a quote |
| Audubon County | Zone 1 | Not published | Get a quote |
| Benton County | Zone 1 | Not published | Get a quote |
| Black Hawk County | Zone 1 | Not published | Get a quote |
| Boone County | Zone 1 | Not published | Get a quote |
| Bremer County | Zone 1 | Not published | Get a quote |
| Buchanan County | Zone 1 | Not published | Get a quote |
| Buena Vista County | Zone 1 | Not published | Get a quote |
| Butler County | Zone 1 | Not published | Get a quote |
| Calhoun County | Zone 1 | Not published | Get a quote |
| Carroll County | Zone 1 | Not published | Get a quote |
| Cass County | Zone 1 | Not published | Get a quote |
| Cedar County | Zone 1 | Not published | Get a quote |
| Cerro Gordo County | Zone 1 | Not published | Get a quote |
| Cherokee County | Zone 1 | Not published | Get a quote |
| Chickasaw County | Zone 1 | Not published | Get a quote |
| Clarke County | Zone 1 | Not published | Get a quote |
| Clay County | Zone 1 | Not published | Get a quote |
| Clayton County | Zone 1 | Not published | Get a quote |
| Clinton County | Zone 1 | Not published | Get a quote |
| Crawford County | Zone 1 | Not published | Get a quote |
| Dallas County | Zone 1 | Not published | Get a quote |
| Davis County | Zone 1 | Not published | Get a quote |
| Decatur County | Zone 1 | Not published | Get a quote |
| Delaware County | Zone 1 | Not published | Get a quote |
| Des Moines County | Zone 1 | Not published | Get a quote |
| Dickinson County | Zone 1 | Not published | Get a quote |
| Dubuque County | Zone 1 | Not published | Dubuque |
| Emmet County | Zone 1 | Not published | Get a quote |
| Fayette County | Zone 1 | Not published | Get a quote |
| Floyd County | Zone 1 | Not published | Get a quote |
| Franklin County | Zone 1 | Not published | Get a quote |
| Fremont County | Zone 1 | Not published | Get a quote |
| Greene County | Zone 1 | Not published | Get a quote |
| Grundy County | Zone 1 | Not published | Get a quote |
| Guthrie County | Zone 1 | Not published | Get a quote |
| Hamilton County | Zone 1 | Not published | Get a quote |
| Hancock County | Zone 1 | Not published | Get a quote |
| Hardin County | Zone 1 | Not published | Get a quote |
| Harrison County | Zone 1 | Not published | Get a quote |
| Henry County | Zone 1 | Not published | Get a quote |
| Howard County | Zone 1 | Not published | Get a quote |
| Humboldt County | Zone 1 | Not published | Get a quote |
| Ida County | Zone 1 | Not published | Get a quote |
| Iowa County | Zone 1 | Not published | Get a quote |
| Jackson County | Zone 1 | Not published | Get a quote |
| Jasper County | Zone 1 | Not published | Get a quote |
| Jefferson County | Zone 1 | Not published | Get a quote |
| Johnson County | Zone 1 | Not published | Get a quote |
| Jones County | Zone 1 | Not published | Get a quote |
| Keokuk County | Zone 1 | Not published | Get a quote |
| Kossuth County | Zone 1 | Not published | Get a quote |
| Lee County | Zone 1 | Not published | Get a quote |
| Linn County | Zone 1 | Not published | Get a quote |
| Louisa County | Zone 1 | Not published | Get a quote |
| Lucas County | Zone 1 | Not published | Get a quote |
| Lyon County | Zone 1 | Not published | Get a quote |
| Madison County | Zone 1 | Not published | Get a quote |
| Mahaska County | Zone 1 | Not published | Get a quote |
| Marion County | Zone 1 | Not published | Get a quote |
| Marshall County | Zone 1 | Not published | Get a quote |
| Mills County | Zone 1 | Not published | Get a quote |
| Mitchell County | Zone 1 | Not published | Get a quote |
| Monona County | Zone 1 | Not published | Get a quote |
| Monroe County | Zone 1 | Not published | Get a quote |
| Montgomery County | Zone 1 | Not published | Get a quote |
| Muscatine County | Zone 1 | Not published | Get a quote |
| O'Brien County | Zone 1 | Not published | Get a quote |
| Osceola County | Zone 1 | Not published | Get a quote |
| Page County | Zone 1 | Not published | Get a quote |
| Palo Alto County | Zone 1 | Not published | Get a quote |
| Plymouth County | Zone 1 | Not published | Get a quote |
| Pocahontas County | Zone 1 | Not published | Get a quote |
| Polk County | Zone 1 | Not published | Des Moines |
| Pottawattamie County | Zone 1 | Not published | Get a quote |
| Poweshiek County | Zone 1 | Not published | Get a quote |
| Ringgold County | Zone 1 | Not published | Get a quote |
| Sac County | Zone 1 | Not published | Get a quote |
| Scott County | Zone 1 | Not published | Get a quote |
| Shelby County | Zone 1 | Not published | Get a quote |
| Sioux County | Zone 1 | Not published | Get a quote |
| Story County | Zone 1 | Not published | Get a quote |
| Tama County | Zone 1 | Not published | Get a quote |
| Taylor County | Zone 1 | Not published | Get a quote |
| Union County | Zone 1 | Not published | Get a quote |
| Van Buren County | Zone 1 | Not published | Get a quote |
| Wapello County | Zone 1 | Not published | Get a quote |
| Warren County | Zone 1 | Not published | Get a quote |
| Washington County | Zone 1 | Not published | Get a quote |
| Wayne County | Zone 1 | Not published | Get a quote |
| Webster County | Zone 1 | Not published | Get a quote |
| Winnebago County | Zone 1 | Not published | Get a quote |
| Winneshiek County | Zone 1 | Not published | Get a quote |
| Woodbury County | Zone 1 | Not published | Sioux City |
| Worth County | Zone 1 | Not published | Get a quote |
| Wright County | Zone 1 | Not published | Get a quote |
No counties match that filter.
EPA Radon Zone from the US EPA Map of Radon Zones. Statewide figures from Iowa HHS and the Iowa Radon Survey. Counties marked "Not published" have no per-county average from a primary source, so no figure is shown.
Frequently Asked Questions
What are radon levels by county in Iowa?
All 99 Iowa counties are classified by the EPA as Radon Zone 1, the highest-risk category, meaning the predicted average indoor level is above 4 pCi/L. Statewide, Iowa averages about 8.5 pCi/L per Iowa HHS. Iowa does not publish a single official average for every individual county, and county averages listed on third-party sites are usually user-submitted rather than official, so the only reliable way to know a specific home is to test it.
Which Iowa counties are in EPA Radon Zone 1?
Every one of Iowa’s 99 counties is in EPA Radon Zone 1. Iowa is the only state where all counties carry the highest-risk EPA zone designation, according to the EPA Map of Radon Zones.
How do I find radon levels by zip code in Iowa?
There is no official radon average by zip code, and online zip-code or county averages are typically user-submitted estimates, not authoritative figures. Because radon varies house to house even on the same street, a short-term or long-term test of your own home is the only accurate way to find your level. A credentialed specialist can run that test for you.
What is the average radon level in Iowa?
The Iowa Department of Health and Human Services reports a statewide average indoor radon level around 8.5 pCi/L, compared with a US average near 1.3 pCi/L. The Iowa Radon Survey found roughly 71.6% of Iowa homes test at or above the EPA action level of 4 pCi/L, the highest share of any state.
Know Your County. Now Test Your Home.
Zone and county data cannot tell you your home’s level. Get a free, no-obligation quote from a credentialed specialist.
Updated