Is Llano County, TX a radon risk area?

EPA places Llano 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. Nationally, Llano County ranks higher in radon potential than 48% of rated counties (the 48th percentile).

How Llano County compares

About 23,163 people live in Llano County, Texas, spread over 934.069 square miles. That works out to roughly 25 people per square mile. Rank 576 by population within its EPA zone puts Llano County at the 44th percentile among zone peers. Llano County falls in EPA Radon Region 6, one of 503 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

EPA's Zone 2 rating for Llano County sits below its own 4 pCi/L action level but above the national indoor average of about 1.3 pCi/L. Llano County's Zone 2 rating sits in the middle nationally; EPA's guidance is unchanged by that — test every home regardless of its zone.

Testing and mitigation in Llano County

Nothing about Llano County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find Texas's state radon program

Llano County's test kit answers today; a Airthings radon monitor keeps answering for Llano 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 Llano County's numbers. Whatever zone Llano County carries, the zone explainer covers what it does and doesn't tell you about any one house.