What EPA's radon map says about Sterling County

Sterling 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 1st percentile for radon potential — Sterling County outranks 1% of every county EPA has rated.

How Sterling County compares

About 1,387 people live in Sterling County, Texas, spread over 923.449 square miles. Population density there runs about 2 people per square mile. Among counties sharing Sterling County's EPA zone, it outranks 3% of them by population. EPA's geology-based Region 6 groups Sterling County with 502 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Sterling County's predicted average sits below the national indoor average of about 1.3 pCi/L, well under EPA's 4 pCi/L action level. Even at Zone 3, Sterling County homes are not guaranteed a low reading — zone is a county-wide average, and EPA recommends testing every home regardless of zone.

Next steps for a home in Sterling County

Mitigation cost doesn't depend on Sterling 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

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

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.