What EPA's radon map says about Liberty County

EPA's own radon map rates Liberty County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally, Liberty County ranks higher in radon potential than 67% of rated counties (the 67th percentile).

Liberty County by the numbers

About 1,934 people live in Liberty County, Montana, spread over 1,429.988 square miles. Population density there runs about 1 people per square mile. Among counties sharing Liberty County's EPA zone, it outranks 3% of them by population. EPA's geology-based Region 8 groups Liberty County with 290 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Liberty County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. Being in Zone 1 raises the odds Liberty County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

Next steps for a home in Liberty County

Mitigation cost doesn't depend on Liberty 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 Montana's state radon program

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

Liberty 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.