What EPA's radon map says about Durham County

EPA places Durham County in Zone 3 - Low Potential — a predicted county-wide average indoor radon level below 2 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Durham County sits at the 30th percentile nationally for radon potential — above 30 of every 100 rated counties.

How Durham County compares

About 343,628 people live in Durham County, North Carolina, spread over 287.555 square miles. Averaged across its land area, Durham County runs about 1,195 people per square mile. Among counties sharing Durham County's EPA zone, it outranks 93% of them by population. EPA's geology-based Region 4 groups Durham County with 735 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Durham County

Durham County's Zone 3 prediction undercuts the roughly 1.3 pCi/L most US homes average, nowhere near EPA's 4 pCi/L threshold for recommending mitigation. Even at Zone 3, Durham County homes are not guaranteed a low reading — zone is a county-wide average, and EPA recommends testing every home regardless of zone.

Next steps for a home in Durham County

Mitigation cost doesn't depend on Durham 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

Durham County's test kit answers today; a Airthings radon monitor keeps answering for Durham 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 Durham County's numbers. Whatever zone Durham County carries, the zone explainer covers what it does and doesn't tell you about any one house.