Indiana: 92 counties covered
Of 92 rated Indiana counties, 57 are in EPA's highest radon-potential zone (Zone 1) — but every county page links to testing guidance regardless of zone, because a county rating is a county-wide average, not a reading for any one house.
- Marion County
- Lake County
- Allen County
- Hamilton County
- St. Joseph County
- Elkhart County
- Tippecanoe County
- Hendricks County
- Vanderburgh County
- Porter County
- Johnson County
- Monroe County
- Madison County
- Clark County
- Delaware County
- LaPorte County
- Vigo County
- Hancock County
- Bartholomew County
- Howard County
- Floyd County
- Kosciusko County
- Boone County
- Morgan County
- Grant County
- Wayne County
- Warrick County
- Dearborn County
- Henry County
- Noble County
- Jackson County
- Marshall County
- Shelby County
- Lawrence County
- DeKalb County
- Dubois County
- LaGrange County
- Harrison County
- Montgomery County
- Putnam County
- Cass County
- Huntington County
- Adams County
- Knox County
- Miami County
- Whitley County
- Steuben County
- Daviess County
- Jasper County
- Gibson County
- Jefferson County
- Clinton County
- Greene County
- Wabash County
- Ripley County
- Wells County
- Washington County
- Jennings County
- Clay County
- Decatur County
- Posey County
- White County
- Scott County
- Randolph County
- Starke County
- Fayette County
- Franklin County
- Owen County
- Sullivan County
- Carroll County
- Spencer County
- Jay County
- Fulton County
- Orange County
- Perry County
- Fountain County
- Rush County
- Parke County
- Brown County
- Vermillion County
- Tipton County
- Newton County
- Pulaski County
- Pike County
- Blackford County
- Crawford County
- Switzerland County
- Martin County
- Benton County
- Warren County
- Union County
- Ohio County