What EPA's radon map says about Mason County

EPA places Mason County in Zone 2 - Moderate Potential — a predicted county-wide average indoor radon level between 2 and 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. That puts Mason County in the 35th percentile nationally for radon potential — higher than 35% of the counties EPA has rated.

Mason County by the numbers

About 3,987 people live in Mason County, Texas, spread over 928.836 square miles. Population density there runs about 4 people per square mile. Among counties sharing Mason County's EPA zone, it outranks 7% of them by population. EPA's geology-based Region 6 groups Mason County with 502 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Mason County's predicted average falls between EPA's 4 pCi/L action level and the national indoor average of about 1.3 pCi/L (outdoor air runs roughly 0.4 pCi/L). Nothing about a Zone 2 label lowers the case for testing in Mason County — EPA recommends it in every zone, moderate included.

If Mason County tests above the action level

Mitigation cost doesn't depend on Mason 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

Mason County's test kit answers today; a Airthings radon monitor keeps answering for Mason County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.

More on how this number was built

The methodology guide shows exactly which EPA and Census sources feed Mason County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.