Missouri Radon Levels
11Zone 1 (High)
97Zone 2 (Moderate)
7Zone 3 (Low)
10% of counties in Missouri are classified as EPA Zone 1 (highest radon potential), meaning predicted average indoor radon levels exceed 4 pCi/L — the EPA action level. The EPA recommends that all homes be tested for radon, regardless of zone classification.
| County | EPA Zone | Risk Level |
|---|---|---|
| Adair County | Zone 2 | Moderate Potential |
| Andrew County | Zone 1 | Highest Potential |
| Atchison County | Zone 1 | Highest Potential |
| Audrain County | Zone 2 | Moderate Potential |
| Barry County | Zone 2 | Moderate Potential |
| Barton County | Zone 2 | Moderate Potential |
| Bates County | Zone 2 | Moderate Potential |
| Benton County | Zone 2 | Moderate Potential |
| Bollinger County | Zone 2 | Moderate Potential |
| Boone County | Zone 2 | Moderate Potential |
| Buchanan County | Zone 1 | Highest Potential |
| Butler County | Zone 3 | Lowest Potential |
| Caldwell County | Zone 2 | Moderate Potential |
| Callaway County | Zone 2 | Moderate Potential |
| Camden County | Zone 2 | Moderate Potential |
| Cape Girardeau County | Zone 2 | Moderate Potential |
| Carroll County | Zone 2 | Moderate Potential |
| Carter County | Zone 2 | Moderate Potential |
| Cass County | Zone 1 | Highest Potential |
| Cedar County | Zone 2 | Moderate Potential |
| Chariton County | Zone 2 | Moderate Potential |
| Christian County | Zone 2 | Moderate Potential |
| Clark County | Zone 2 | Moderate Potential |
| Clay County | Zone 1 | Highest Potential |
| Clinton County | Zone 1 | Highest Potential |
| Cole County | Zone 2 | Moderate Potential |
| Cooper County | Zone 2 | Moderate Potential |
| Crawford County | Zone 2 | Moderate Potential |
| Dade County | Zone 2 | Moderate Potential |
| Dallas County | Zone 2 | Moderate Potential |
| Daviess County | Zone 2 | Moderate Potential |
| DeKalb County | Zone 2 | Moderate Potential |
| Dent County | Zone 2 | Moderate Potential |
| Douglas County | Zone 2 | Moderate Potential |
| Dunklin County | Zone 3 | Lowest Potential |
| Franklin County | Zone 2 | Moderate Potential |
| Gasconade County | Zone 2 | Moderate Potential |
| Gentry County | Zone 2 | Moderate Potential |
| Greene County | Zone 2 | Moderate Potential |
| Grundy County | Zone 2 | Moderate Potential |
| Harrison County | Zone 2 | Moderate Potential |
| Henry County | Zone 2 | Moderate Potential |
| Hickory County | Zone 2 | Moderate Potential |
| Holt County | Zone 1 | Highest Potential |
| Howard County | Zone 2 | Moderate Potential |
| Howell County | Zone 2 | Moderate Potential |
| Iron County | Zone 1 | Highest Potential |
| Jackson County | Zone 1 | Highest Potential |
| Jasper County | Zone 2 | Moderate Potential |
| Jefferson County | Zone 2 | Moderate Potential |
| Johnson County | Zone 2 | Moderate Potential |
| Knox County | Zone 2 | Moderate Potential |
| Laclede County | Zone 2 | Moderate Potential |
| Lafayette County | Zone 2 | Moderate Potential |
| Lawrence County | Zone 2 | Moderate Potential |
| Lewis County | Zone 2 | Moderate Potential |
| Lincoln County | Zone 2 | Moderate Potential |
| Linn County | Zone 2 | Moderate Potential |
| Livingston County | Zone 2 | Moderate Potential |
| McDonald County | Zone 2 | Moderate Potential |
| Macon County | Zone 2 | Moderate Potential |
| Madison County | Zone 2 | Moderate Potential |
| Maries County | Zone 2 | Moderate Potential |
| Marion County | Zone 2 | Moderate Potential |
| Mercer County | Zone 2 | Moderate Potential |
| Miller County | Zone 2 | Moderate Potential |
| Mississippi County | Zone 3 | Lowest Potential |
| Moniteau County | Zone 2 | Moderate Potential |
| Monroe County | Zone 2 | Moderate Potential |
| Montgomery County | Zone 2 | Moderate Potential |
| Morgan County | Zone 2 | Moderate Potential |
| New Madrid County | Zone 3 | Lowest Potential |
| Newton County | Zone 2 | Moderate Potential |
| Nodaway County | Zone 1 | Highest Potential |
| Oregon County | Zone 2 | Moderate Potential |
| Osage County | Zone 2 | Moderate Potential |
| Ozark County | Zone 2 | Moderate Potential |
| Pemiscot County | Zone 3 | Lowest Potential |
| Perry County | Zone 2 | Moderate Potential |
| Pettis County | Zone 2 | Moderate Potential |
| Phelps County | Zone 2 | Moderate Potential |
| Pike County | Zone 2 | Moderate Potential |
| Platte County | Zone 1 | Highest Potential |
| Polk County | Zone 2 | Moderate Potential |
| Pulaski County | Zone 2 | Moderate Potential |
| Putnam County | Zone 2 | Moderate Potential |
| Ralls County | Zone 2 | Moderate Potential |
| Randolph County | Zone 2 | Moderate Potential |
| Ray County | Zone 2 | Moderate Potential |
| Reynolds County | Zone 2 | Moderate Potential |
| Ripley County | Zone 2 | Moderate Potential |
| St. Charles County | Zone 2 | Moderate Potential |
| St. Clair County | Zone 2 | Moderate Potential |
| Ste. Genevieve County | Zone 2 | Moderate Potential |
| St. Francois County | Zone 2 | Moderate Potential |
| St. Louis County | Zone 2 | Moderate Potential |
| Saline County | Zone 2 | Moderate Potential |
| Schuyler County | Zone 2 | Moderate Potential |
| Scotland County | Zone 2 | Moderate Potential |
| Scott County | Zone 3 | Lowest Potential |
| Shannon County | Zone 2 | Moderate Potential |
| Shelby County | Zone 2 | Moderate Potential |
| Stoddard County | Zone 3 | Lowest Potential |
| Stone County | Zone 2 | Moderate Potential |
| Sullivan County | Zone 2 | Moderate Potential |
| Taney County | Zone 2 | Moderate Potential |
| Texas County | Zone 2 | Moderate Potential |
| Vernon County | Zone 2 | Moderate Potential |
| Warren County | Zone 2 | Moderate Potential |
| Washington County | Zone 2 | Moderate Potential |
| Wayne County | Zone 2 | Moderate Potential |
| Webster County | Zone 2 | Moderate Potential |
| Worth County | Zone 2 | Moderate Potential |
| Wright County | Zone 2 | Moderate Potential |
| St. Louis city | Zone 2 | Moderate Potential |