Galveston County, TX: EPA's radon zone, explained

Galveston County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. That puts Galveston County in the 31st percentile nationally for radon potential — higher than 31% of the counties EPA has rated.

Galveston County by the numbers

Galveston County, Texas is home to about 367,407 people across 379.413 square miles. Averaged across its land area, Galveston County runs about 968 people per square mile. By population, Galveston County is the 73rd largest of every county sharing its EPA zone — the 93rd percentile by population within that zone. Geologically, Galveston 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 Galveston County

Galveston 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. A Zone 3 label describes Galveston 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 Galveston County

For a Galveston County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Texas's state radon program

For Galveston County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Galveston County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

Where Galveston County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Galveston County's numbers. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.