What EPA's radon map says about Gillespie County

Gillespie County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Gillespie County sits at the 17th percentile nationally for radon potential — above 17 of every 100 rated counties.

Where Gillespie County sits nationally

About 28,159 people live in Gillespie County, Texas, spread over 1,058.205 square miles. That works out to roughly 27 people per square mile. Among counties sharing Gillespie County's EPA zone, it outranks 51% of them by population. Gillespie County falls in EPA Radon Region 6, one of 503 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

A Zone 3 county like Gillespie County is predicted closer to the 0.4 pCi/L typical outdoors than to EPA's 4 pCi/L action level. A Zone 3 label describes Gillespie County's average, not any one basement or slab in it — testing is still the only way an individual homeowner actually finds out.

Testing and mitigation in Gillespie County

Mitigation cost doesn't depend on Gillespie 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

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

Gillespie County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.