South Dakota Radon Levels
48Zone 1 (High)
18Zone 2 (Moderate)
0Zone 3 (Low)
73% of counties in South Dakota 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 |
|---|---|---|
| Aurora County | Zone 1 | Highest Potential |
| Beadle County | Zone 1 | Highest Potential |
| Bennett County | Zone 2 | Moderate Potential |
| Bon Homme County | Zone 1 | Highest Potential |
| Brookings County | Zone 1 | Highest Potential |
| Brown County | Zone 1 | Highest Potential |
| Brule County | Zone 1 | Highest Potential |
| Buffalo County | Zone 1 | Highest Potential |
| Butte County | Zone 2 | Moderate Potential |
| Campbell County | Zone 1 | Highest Potential |
| Charles Mix County | Zone 1 | Highest Potential |
| Clark County | Zone 1 | Highest Potential |
| Clay County | Zone 1 | Highest Potential |
| Codington County | Zone 1 | Highest Potential |
| Corson County | Zone 1 | Highest Potential |
| Custer County | Zone 2 | Moderate Potential |
| Davison County | Zone 1 | Highest Potential |
| Day County | Zone 1 | Highest Potential |
| Deuel County | Zone 1 | Highest Potential |
| Dewey County | Zone 2 | Moderate Potential |
| Douglas County | Zone 1 | Highest Potential |
| Edmunds County | Zone 1 | Highest Potential |
| Fall River County | Zone 2 | Moderate Potential |
| Faulk County | Zone 1 | Highest Potential |
| Grant County | Zone 1 | Highest Potential |
| Gregory County | Zone 2 | Moderate Potential |
| Haakon County | Zone 2 | Moderate Potential |
| Hamlin County | Zone 1 | Highest Potential |
| Hand County | Zone 1 | Highest Potential |
| Hanson County | Zone 1 | Highest Potential |
| Harding County | Zone 2 | Moderate Potential |
| Hughes County | Zone 1 | Highest Potential |
| Hutchinson County | Zone 1 | Highest Potential |
| Hyde County | Zone 1 | Highest Potential |
| Jackson County | Zone 2 | Moderate Potential |
| Jerauld County | Zone 1 | Highest Potential |
| Jones County | Zone 2 | Moderate Potential |
| Kingsbury County | Zone 1 | Highest Potential |
| Lake County | Zone 1 | Highest Potential |
| Lawrence County | Zone 2 | Moderate Potential |
| Lincoln County | Zone 1 | Highest Potential |
| Lyman County | Zone 1 | Highest Potential |
| McCook County | Zone 1 | Highest Potential |
| McPherson County | Zone 1 | Highest Potential |
| Marshall County | Zone 1 | Highest Potential |
| Meade County | Zone 2 | Moderate Potential |
| Mellette County | Zone 2 | Moderate Potential |
| Miner County | Zone 1 | Highest Potential |
| Minnehaha County | Zone 1 | Highest Potential |
| Moody County | Zone 1 | Highest Potential |
| Pennington County | Zone 2 | Moderate Potential |
| Perkins County | Zone 1 | Highest Potential |
| Potter County | Zone 1 | Highest Potential |
| Roberts County | Zone 1 | Highest Potential |
| Sanborn County | Zone 1 | Highest Potential |
| Shannon County | Zone 2 | Moderate Potential |
| Spink County | Zone 1 | Highest Potential |
| Stanley County | Zone 1 | Highest Potential |
| Sully County | Zone 1 | Highest Potential |
| Todd County | Zone 2 | Moderate Potential |
| Tripp County | Zone 2 | Moderate Potential |
| Turner County | Zone 1 | Highest Potential |
| Union County | Zone 1 | Highest Potential |
| Walworth County | Zone 1 | Highest Potential |
| Yankton County | Zone 1 | Highest Potential |
| Ziebach County | Zone 2 | Moderate Potential |