What EPA's radon map says about Clinton County

EPA's own radon map rates Clinton County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally that's the 88th percentile for radon potential — Clinton County outranks 88% of every county EPA has rated.

How Clinton County compares

About 42,019 people live in Clinton County, Ohio, spread over 408.731 square miles. That works out to roughly 103 people per square mile. Among counties sharing Clinton County's EPA zone, it outranks 66% of them by population. Geologically, Clinton County is grouped into EPA Region 5 alongside 523 other counties that share its rock and soil setting.

What this actually means for a house in Clinton County

Clinton County's predicted average sits above EPA's own action level of 4 pCi/L — the concentration at which EPA recommends fixing a home — versus a national average around 1.3 pCi/L indoors and 0.4 pCi/L outdoors. Being in Zone 1 raises the odds Clinton County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

Next steps for a home in Clinton County

Mitigation cost doesn't depend on Clinton County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find Ohio's state radon program

Clinton County's test kit answers today; a Airthings radon monitor keeps answering for Clinton County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

More on how this number was built

Clinton County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.