What EPA's radon map says about Adams County

EPA's own radon map rates Adams County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally that's the 67th percentile for radon potential — Adams County outranks 67% of every county EPA has rated.

How Adams County compares

About 2,141 people live in Adams County, North Dakota, spread over 987.547 square miles. Population density there runs about 2 people per square mile. Among counties sharing Adams County's EPA zone, it outranks 4% of them by population. EPA's geology-based Region 8 groups Adams County with 290 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Where the national indoor average runs about 1.3 pCi/L, Adams County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. That doesn't mean every Adams County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.

If Adams County tests above the action level

Mitigation cost doesn't depend on Adams 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 North Dakota's state radon program

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

More on how this number was built

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.