What EPA's radon map says about Gibson County

Gibson County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. That puts Gibson County in the 22nd percentile nationally for radon potential — higher than 22% of the counties EPA has rated.

Where Gibson County sits nationally

About 51,422 people live in Gibson County, Tennessee, spread over 602.745 square miles. That works out to roughly 85 people per square mile. Among counties sharing Gibson County's EPA zone, it outranks 68% of them by population. Gibson 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 Gibson County

At Zone 3, Gibson 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. A Zone 3 label describes Gibson County's average, not any one basement or slab in it — testing is still the only way an individual homeowner actually finds out.

If Gibson County tests above the action level

Mitigation cost doesn't depend on Gibson County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find Tennessee's state radon program

Gibson County's test kit answers today; a Airthings radon monitor keeps answering for Gibson County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.

More on how this number was built

The methodology guide shows exactly which EPA and Census sources feed Gibson County's numbers. Whatever zone Gibson County carries, the zone explainer covers what it does and doesn't tell you about any one house.