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

EPA places McMullen County in Zone 3 - Low Potential — a predicted county-wide average indoor radon level below 2 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. That puts McMullen County in the 0th percentile nationally for radon potential — higher than 0% of the counties EPA has rated.

How McMullen County compares

McMullen County, Texas is home to about 565 people across 1,139.799 square miles. Population density there runs about 0 people per square mile. By population, McMullen County is the 1023rd largest of every county sharing its EPA zone — the 1st percentile by population within that zone. Geologically, McMullen 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 McMullen County

Well clear of both the 1.3 pCi/L national indoor average and EPA's 4 pCi/L action level, McMullen County's Zone 3 prediction is the low end of the scale. Don't read Zone 3 as a pass for McMullen County — EPA's guidance to test every home makes no exception for counties predicted low.

Testing and mitigation in McMullen County

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

Where McMullen County's figures come from

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.