Clermont County, OH: EPA's radon zone, explained

EPA's own radon map rates Clermont County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Nationally, Clermont County ranks higher in radon potential than 62% of rated counties (the 62nd percentile).

Where Clermont County sits nationally

Clermont County, Ohio is home to about 214,123 people across 452.56 square miles. Population density there runs about 473 people per square mile. By population, Clermont County is the 114th largest of every county sharing its EPA zone — the 89th percentile by population within that zone. Clermont 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

Clermont County's predicted average falls between EPA's 4 pCi/L action level and the national indoor average of about 1.3 pCi/L (outdoor air runs roughly 0.4 pCi/L). Nothing about a Zone 2 label lowers the case for testing in Clermont County — EPA recommends it in every zone, moderate included.

Testing and mitigation in Clermont County

For a Clermont County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Ohio's state radon program

For Clermont County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Clermont County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.

Where Clermont County's figures come from

Clermont 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.