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

EPA places Cumberland 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. That puts Cumberland County in the 72nd percentile nationally for radon potential — higher than 72% of the counties EPA has rated.

Where Cumberland County sits nationally

Cumberland County, Kentucky is home to about 6,047 people across 305.147 square miles. Population density there runs about 20 people per square mile. By population, Cumberland County is the 880th largest of every county sharing its EPA zone — the 17th percentile by population within that zone. EPA's geology-based Region 4 groups Cumberland County with 735 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Cumberland County

Cumberland 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. Being in Zone 1 raises the odds Cumberland County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

If Cumberland County tests above the action level

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

Cumberland 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.