What EPA's radon map says about Webb County

EPA's own radon map rates Webb County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Nationally, Webb County ranks higher in radon potential than 30% of rated counties (the 30th percentile).

How Webb County compares

About 272,823 people live in Webb County, Texas, spread over 3,361.498 square miles. That works out to roughly 81 people per square mile. Among counties sharing Webb County's EPA zone, it outranks 91% of them by population. Geologically, Webb County is grouped into EPA Region 6 alongside 502 other counties that share its rock and soil setting.

What this actually means for a house in Webb County

At Zone 3, Webb County's predicted county average is under the national indoor average (~1.3 pCi/L) and well below EPA's 4 pCi/L action level — outdoor air nationally runs about 0.4 pCi/L for comparison. A Zone 3 label describes Webb 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 Webb County

Mitigation cost doesn't depend on Webb 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

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

Webb 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.