What EPA's radon map says about Martin County

EPA's own radon map rates Martin County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Rank it against the rest of the country and Martin County lands in the 14th percentile for radon potential.

Where Martin County sits nationally

About 21,523 people live in Martin County, North Carolina, spread over 456.412 square miles. Population density there runs about 47 people per square mile. Among counties sharing Martin County's EPA zone, it outranks 43% of them by population. Geologically, Martin County is grouped into EPA Region 4 alongside 735 other counties that share its rock and soil setting.

What this actually means for a house in Martin County

At Zone 3, Martin 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. Low doesn't mean zero: EPA's own data shows homes in Zone 3 counties like Martin County testing above the action level often enough that skipping a test isn't the safe assumption.

Next steps for a home in Martin County

Mitigation cost doesn't depend on Martin 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 North Carolina's state radon program

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