Indiana Radon Levels
57Zone 1 (High)
35Zone 2 (Moderate)
0Zone 3 (Low)
62% of counties in Indiana 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 |
|---|---|---|
| Adams County | Zone 1 | Highest Potential |
| Allen County | Zone 1 | Highest Potential |
| Bartholomew County | Zone 1 | Highest Potential |
| Benton County | Zone 1 | Highest Potential |
| Blackford County | Zone 1 | Highest Potential |
| Boone County | Zone 1 | Highest Potential |
| Brown County | Zone 2 | Moderate Potential |
| Carroll County | Zone 1 | Highest Potential |
| Cass County | Zone 1 | Highest Potential |
| Clark County | Zone 1 | Highest Potential |
| Clay County | Zone 2 | Moderate Potential |
| Clinton County | Zone 1 | Highest Potential |
| Crawford County | Zone 2 | Moderate Potential |
| Daviess County | Zone 2 | Moderate Potential |
| Dearborn County | Zone 2 | Moderate Potential |
| Decatur County | Zone 1 | Highest Potential |
| DeKalb County | Zone 1 | Highest Potential |
| Delaware County | Zone 1 | Highest Potential |
| Dubois County | Zone 2 | Moderate Potential |
| Elkhart County | Zone 1 | Highest Potential |
| Fayette County | Zone 1 | Highest Potential |
| Floyd County | Zone 2 | Moderate Potential |
| Fountain County | Zone 1 | Highest Potential |
| Franklin County | Zone 2 | Moderate Potential |
| Fulton County | Zone 1 | Highest Potential |
| Gibson County | Zone 2 | Moderate Potential |
| Grant County | Zone 1 | Highest Potential |
| Greene County | Zone 2 | Moderate Potential |
| Hamilton County | Zone 1 | Highest Potential |
| Hancock County | Zone 1 | Highest Potential |
| Harrison County | Zone 1 | Highest Potential |
| Hendricks County | Zone 1 | Highest Potential |
| Henry County | Zone 1 | Highest Potential |
| Howard County | Zone 1 | Highest Potential |
| Huntington County | Zone 1 | Highest Potential |
| Jackson County | Zone 2 | Moderate Potential |
| Jasper County | Zone 2 | Moderate Potential |
| Jay County | Zone 1 | Highest Potential |
| Jefferson County | Zone 2 | Moderate Potential |
| Jennings County | Zone 1 | Highest Potential |
| Johnson County | Zone 1 | Highest Potential |
| Knox County | Zone 2 | Moderate Potential |
| Kosciusko County | Zone 1 | Highest Potential |
| LaGrange County | Zone 1 | Highest Potential |
| Lake County | Zone 2 | Moderate Potential |
| LaPorte County | Zone 2 | Moderate Potential |
| Lawrence County | Zone 1 | Highest Potential |
| Madison County | Zone 1 | Highest Potential |
| Marion County | Zone 1 | Highest Potential |
| Marshall County | Zone 1 | Highest Potential |
| Martin County | Zone 2 | Moderate Potential |
| Miami County | Zone 1 | Highest Potential |
| Monroe County | Zone 1 | Highest Potential |
| Montgomery County | Zone 1 | Highest Potential |
| Morgan County | Zone 2 | Moderate Potential |
| Newton County | Zone 2 | Moderate Potential |
| Noble County | Zone 1 | Highest Potential |
| Ohio County | Zone 2 | Moderate Potential |
| Orange County | Zone 1 | Highest Potential |
| Owen County | Zone 2 | Moderate Potential |
| Parke County | Zone 2 | Moderate Potential |
| Perry County | Zone 2 | Moderate Potential |
| Pike County | Zone 2 | Moderate Potential |
| Porter County | Zone 2 | Moderate Potential |
| Posey County | Zone 2 | Moderate Potential |
| Pulaski County | Zone 2 | Moderate Potential |
| Putnam County | Zone 1 | Highest Potential |
| Randolph County | Zone 1 | Highest Potential |
| Ripley County | Zone 2 | Moderate Potential |
| Rush County | Zone 1 | Highest Potential |
| St. Joseph County | Zone 1 | Highest Potential |
| Scott County | Zone 1 | Highest Potential |
| Shelby County | Zone 1 | Highest Potential |
| Spencer County | Zone 2 | Moderate Potential |
| Starke County | Zone 2 | Moderate Potential |
| Steuben County | Zone 1 | Highest Potential |
| Sullivan County | Zone 2 | Moderate Potential |
| Switzerland County | Zone 2 | Moderate Potential |
| Tippecanoe County | Zone 1 | Highest Potential |
| Tipton County | Zone 1 | Highest Potential |
| Union County | Zone 1 | Highest Potential |
| Vanderburgh County | Zone 2 | Moderate Potential |
| Vermillion County | Zone 1 | Highest Potential |
| Vigo County | Zone 2 | Moderate Potential |
| Wabash County | Zone 1 | Highest Potential |
| Warren County | Zone 1 | Highest Potential |
| Warrick County | Zone 2 | Moderate Potential |
| Washington County | Zone 1 | Highest Potential |
| Wayne County | Zone 1 | Highest Potential |
| Wells County | Zone 1 | Highest Potential |
| White County | Zone 1 | Highest Potential |
| Whitley County | Zone 1 | Highest Potential |