Coal County, OK: EPA's radon zone, explained

Coal County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Coal County sits at the 3rd percentile nationally for radon potential — above 3 of every 100 rated counties.

Coal County by the numbers

Coal County, Oklahoma is home to about 5,414 people across 516.772 square miles. Averaged across its land area, Coal County runs about 10 people per square mile. By population, Coal County is the 935th largest of every county sharing its EPA zone — the 9th percentile by population within that zone. EPA's geology-based Region 6 groups Coal County with 502 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

At Zone 3, Coal County's predicted county average is under the national indoor average (~1.3 pCi/L) and well below EPA's 4 pCi/L action level — outdoor air nationally runs about 0.4 pCi/L for comparison. Even at Zone 3, Coal County homes are not guaranteed a low reading — zone is a county-wide average, and EPA recommends testing every home regardless of zone.

If Coal County tests above the action level

For a Coal 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 Oklahoma's state radon program

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

Coal County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.