Is Grand Forks County, ND a radon risk area?

EPA's own radon map rates Grand Forks County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally, Grand Forks County ranks higher in radon potential than 92% of rated counties (the 92nd percentile).

How Grand Forks County compares

About 73,771 people live in Grand Forks County, North Dakota, spread over 1,436.216 square miles. Population density there runs about 51 people per square mile. Rank 240 by population within its EPA zone puts Grand Forks County at the 78th percentile among zone peers. Geologically, Grand Forks County is grouped into EPA Region 8 alongside 290 other counties that share its rock and soil setting.

Zone vs. an actual test

Where the national indoor average runs about 1.3 pCi/L, Grand Forks County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. Being in Zone 1 raises the odds Grand Forks 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.

If Grand Forks County tests above the action level

Nothing about Grand Forks 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

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

More on how this number was built

The methodology guide shows exactly which EPA and Census sources feed Grand Forks County's numbers. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.