Ohio has 88 counties, with 53 classified as EPA Zone 1 (highest risk). With an average radon level of 8.77 pCi/L, Ohio state testing data reveals significantly elevated risks across multiple counties. Testing is highly recommended.
Ohio is the 34th most expansive state in terms of size and the 7th most populous. It also happens to be the 10th most densely populated state in the entire US.
Ohio does have an active radon program, dedicated to educating citizens about the risks associated with the deadly gas. You can find more information on Radon, testing and mitigation at the official page.
Explore radon data organized by metro region, including average levels, hotspot cities, and local mitigation professionals.
Cities with the most user-submitted radon test data, ranked by number of submissions.
| City | Avg User Radon Level | Submissions |
|---|---|---|
| Marietta | 8.00 pCi/L | 5 |
| Cincinnati | 5.20 pCi/L | 5 |
| Hilliard | 11.75 pCi/L | 4 |
| Wilmington | 5.25 pCi/L | 4 |
| Newark | 15.00 pCi/L | 3 |
| Athens | 11.33 pCi/L | 3 |
| Findlay | 10.33 pCi/L | 3 |
| Perrysburg | 9.67 pCi/L | 3 |
| Powell | 8.33 pCi/L | 3 |
| Columbus | 6.00 pCi/L | 3 |
| Chagrin Falls | 4.67 pCi/L | 3 |
| Hamilton | 10.00 pCi/L | 2 |
| Chardon | 5.50 pCi/L | 2 |
| Strongsville | 4.50 pCi/L | 2 |
| Maineville | 10.00 pCi/L | 1 |
| Lancaster | 9.00 pCi/L | 1 |
| West Chester | 9.00 pCi/L | 1 |
| Amherst | 6.00 pCi/L | 1 |
| Chillicothe | 6.00 pCi/L | 1 |
| Lima | 5.00 pCi/L | 1 |
All 88 Ohio counties with their EPA radon zone classification and user-submitted average radon levels.
Browse radon data for individual cities across Ohio. Each city page includes user-submitted radon levels, local contractors, and mitigation resources.