What EPA's radon map says about Carroll County

EPA's own radon map rates Carroll County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Carroll County sits at the 84th percentile nationally for radon potential — above 84 of every 100 rated counties.

Where Carroll County sits nationally

About 26,460 people live in Carroll County, Ohio, spread over 394.673 square miles. Averaged across its land area, Carroll County runs about 67 people per square mile. Among counties sharing Carroll County's EPA zone, it outranks 53% of them by population. Carroll County falls in EPA Radon Region 5, one of 524 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Carroll County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. EPA's guidance doesn't change because of a Zone 1 label: test the house. What changes is the reason to not put it off in Carroll County specifically.

Testing and mitigation in Carroll County

Mitigation cost doesn't depend on Carroll 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

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

More on how this number was built

The methodology guide shows exactly which EPA and Census sources feed Carroll County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.