Is Madison County, NC a radon risk area?

EPA's own radon map rates Madison County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. That puts Madison County in the 47th percentile nationally for radon potential — higher than 47% of the counties EPA has rated.

Where Madison County sits nationally

About 22,352 people live in Madison County, North Carolina, spread over 449.615 square miles. Population density there runs about 50 people per square mile. Rank 589 by population within its EPA zone puts Madison County at the 43rd percentile among zone peers. EPA's geology-based Region 4 groups Madison County with 735 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Neither at the 4 pCi/L action level nor down at the roughly 1.3 pCi/L national indoor norm, Madison County's Zone 2 prediction lands in the gap between the two. Madison County's Zone 2 rating sits in the middle nationally; EPA's guidance is unchanged by that — test every home regardless of its zone.

Testing and mitigation in Madison County

Nothing about Madison County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find North Carolina's state radon program

Madison County's test kit answers today; a Airthings radon monitor keeps answering for Madison 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

Madison County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. Whatever zone Madison County carries, the zone explainer covers what it does and doesn't tell you about any one house.