What EPA's radon map says about McCulloch County

McCulloch County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Nationally that's the 4th percentile for radon potential — McCulloch County outranks 4% of every county EPA has rated.

McCulloch County by the numbers

About 7,448 people live in McCulloch County, Texas, spread over 1,065.601 square miles. That works out to roughly 7 people per square mile. Among counties sharing McCulloch County's EPA zone, it outranks 13% of them by population. Geologically, McCulloch County is grouped into EPA Region 6 alongside 502 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

At Zone 3, McCulloch 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 McCulloch County testing above the action level often enough that skipping a test isn't the safe assumption.

Next steps for a home in McCulloch County

Mitigation cost doesn't depend on McCulloch 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 Texas's state radon program

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