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

EPA's own radon map rates Adams County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Rank it against the rest of the country and Adams County lands in the 84th percentile for radon potential.

How Adams County compares

Adams County, Ohio is home to about 27,671 people across 583.872 square miles. That works out to roughly 47 people per square mile. By population, Adams County is the 488th largest of every county sharing its EPA zone — the 54th percentile by population within that zone. Adams County falls in EPA Radon Region 5, one of 524 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Adams County carries a Zone 1 label because its predicted average clears 4 pCi/L outright — three-plus times the 0.4 pCi/L typical outdoors and above the 1.3 pCi/L most homes see. 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 Adams County specifically.

If Adams County tests above the action level

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

Where Adams County's figures come from

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.