Is St. Clair County, AL a radon risk area?

St. Clair County is mapped as Zone 2 - Moderate Potential by EPA — meaning the county-wide average indoor level is predicted between 2 and 4 pCi/L. Nationally that's the 59th percentile for radon potential — St. Clair County outranks 59% of every county EPA has rated.

St. Clair County by the numbers

About 96,927 people live in St. Clair County, Alabama, spread over 631.61 square miles. Population density there runs about 153 people per square mile. Rank 206 by population within its EPA zone puts St. Clair County at the 80th percentile among zone peers. EPA's geology-based Region 4 groups St. Clair County with 735 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

St. Clair County's predicted average falls between EPA's 4 pCi/L action level and the national indoor average of about 1.3 pCi/L (outdoor air runs roughly 0.4 pCi/L). Middle-of-the-pack doesn't mean risk-free for any one St. Clair County address — a moderate county average still leaves individual homes to test either side of it.

Testing and mitigation in St. Clair County

Nothing about St. Clair 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 Alabama's state radon program

St. Clair County's test kit answers today; a Airthings radon monitor keeps answering for St. Clair 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

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