What EPA's radon map says about Greene County

Greene County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally, Greene County ranks higher in radon potential than 92% of rated counties (the 92nd percentile).

Where Greene County sits nationally

About 73,398 people live in Greene County, Tennessee, spread over 622.169 square miles. Averaged across its land area, Greene County runs about 118 people per square mile. Among counties sharing Greene County's EPA zone, it outranks 77% of them by population. EPA's geology-based Region 4 groups Greene County with 735 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Greene County

Greene County's predicted average sits above EPA's own action level of 4 pCi/L — the concentration at which EPA recommends fixing a home — versus a national average around 1.3 pCi/L indoors and 0.4 pCi/L outdoors. Some Greene 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 Greene County tests above the action level

Mitigation cost doesn't depend on Greene 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

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

More on how this number was built

The methodology guide shows exactly which EPA and Census sources feed Greene County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.