Is Callahan County, TX a radon risk area?

EPA's own radon map rates Callahan County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Nationally that's the 10th percentile for radon potential — Callahan County outranks 10% of every county EPA has rated.

Where Callahan County sits nationally

About 14,615 people live in Callahan County, Texas, spread over 899.372 square miles. Population density there runs about 16 people per square mile. Rank 717 by population within its EPA zone puts Callahan County at the 30th percentile among zone peers. Geologically, Callahan County is grouped into EPA Region 6 alongside 502 other counties that share its rock and soil setting.

Zone vs. an actual test

A Zone 3 county like Callahan County is predicted closer to the 0.4 pCi/L typical outdoors than to EPA's 4 pCi/L action level. Low doesn't mean zero: EPA's own data shows homes in Zone 3 counties like Callahan County testing above the action level often enough that skipping a test isn't the safe assumption.

Testing and mitigation in Callahan County

Nothing about Callahan 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 Texas's state radon program

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