Chatham County, NC: EPA's radon zone, explained

EPA's own radon map rates Chatham County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Nationally, Chatham County ranks higher in radon potential than 25% of rated counties (the 25th percentile).

Where Chatham County sits nationally

Chatham County, North Carolina is home to about 83,874 people across 681.474 square miles. That works out to roughly 123 people per square mile. By population, Chatham County is the 243rd largest of every county sharing its EPA zone — the 77th percentile by population within that zone. Chatham 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 Chatham County

Well clear of both the 1.3 pCi/L national indoor average and EPA's 4 pCi/L action level, Chatham County's Zone 3 prediction is the low end of the scale. A Zone 3 rating means Chatham County's county-wide average is predicted low, but EPA is explicit that a meaningful share of homes in low-potential zones still test above the action level — a low zone is not a reason to skip testing.

If Chatham County tests above the action level

For a Chatham County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find North Carolina's state radon program

For Chatham County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Chatham County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

Where Chatham County's figures come from

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. Whatever zone Chatham County carries, the zone explainer covers what it does and doesn't tell you about any one house.