What EPA's radon map says about Calhoun County

Calhoun County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Nationally that's the 9th percentile for radon potential — Calhoun County outranks 9% of every county EPA has rated.

Calhoun County by the numbers

About 12,754 people live in Calhoun County, Mississippi, spread over 586.573 square miles. Population density there runs about 22 people per square mile. Among counties sharing Calhoun County's EPA zone, it outranks 27% of them by population. Calhoun County falls in EPA Radon Region 4, one of 736 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

At Zone 3, Calhoun 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. Don't read Zone 3 as a pass for Calhoun County — EPA's guidance to test every home makes no exception for counties predicted low.

Next steps for a home in Calhoun County

Mitigation cost doesn't depend on Calhoun 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 Mississippi's state radon program

Calhoun County's test kit answers today; a Airthings radon monitor keeps answering for Calhoun 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 Calhoun County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.