Adair County, KY: EPA's radon zone, explained

EPA places Adair County in Zone 1 - Highest Potential — a predicted county-wide average indoor radon level above 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Adair County sits at the 81st percentile nationally for radon potential — above 81 of every 100 rated counties.

Where Adair County sits nationally

Adair County, Kentucky is home to about 19,239 people across 405.292 square miles. Population density there runs about 47 people per square mile. By population, Adair County is the 588th largest of every county sharing its EPA zone — the 45th percentile by population within that zone. Adair County falls in EPA Radon Region 4, one of 736 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in Adair County

Adair 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. Some Adair County homes will test comfortably under the action level despite the county's Zone 1 rating — the only way to know which kind of home you have is an actual test.

If Adair County tests above the action level

For a Adair 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 Kentucky's state radon program

For Adair County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Adair 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 Adair County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Adair County's numbers. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.