Is Traill County, ND a radon risk area?

Traill County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally that's the 74th percentile for radon potential — Traill County outranks 74% of every county EPA has rated.

Traill County by the numbers

About 7,989 people live in Traill County, North Dakota, spread over 861.871 square miles. Population density there runs about 9 people per square mile. Rank 819 by population within its EPA zone puts Traill County at the 23rd percentile among zone peers. Traill County falls in EPA Radon Region 8, one of 291 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

Traill County's predicted average sits above EPA's own action level of 4 pCi/L — the concentration at which EPA recommends fixing a home — versus a national average around 1.3 pCi/L indoors and 0.4 pCi/L outdoors. Some Traill County homes will test comfortably under the action level despite the county's Zone 1 rating — the only way to know which kind of home you have is an actual test.

Next steps for a home in Traill County

Nothing about Traill 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 North Dakota's state radon program

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