What EPA's radon map says about Madison County

EPA places Madison County in Zone 1 - Highest Potential — a predicted county-wide average indoor radon level above 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Madison County sits at the 98th percentile nationally for radon potential — above 98 of every 100 rated counties.

Where Madison County sits nationally

About 423,355 people live in Madison County, Alabama, spread over 801.619 square miles. That works out to roughly 528 people per square mile. Among counties sharing Madison County's EPA zone, it outranks 95% of them by population. Geologically, Madison 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 Madison County

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Madison County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. EPA's guidance doesn't change because of a Zone 1 label: test the house. What changes is the reason to not put it off in Madison County specifically.

Testing and mitigation in Madison County

Mitigation cost doesn't depend on Madison 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 Alabama'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. RADONZONE-10OFF at checkout knocks 10% off.

More on how this number was built

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.