What EPA's radon map says about Frio County

Frio County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Frio County sits at the 13th percentile nationally for radon potential — above 13 of every 100 rated counties.

How Frio County compares

About 19,520 people live in Frio County, Texas, spread over 1,133.501 square miles. Averaged across its land area, Frio County runs about 17 people per square mile. Among counties sharing Frio County's EPA zone, it outranks 39% of them by population. Frio County falls in EPA Radon Region 6, one of 503 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

Well clear of both the 1.3 pCi/L national indoor average and EPA's 4 pCi/L action level, Frio County's Zone 3 prediction is the low end of the scale. Low doesn't mean zero: EPA's own data shows homes in Zone 3 counties like Frio County testing above the action level often enough that skipping a test isn't the safe assumption.

Next steps for a home in Frio County

Mitigation cost doesn't depend on Frio 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

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

Frio County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.