Radon in North Dakota

About 6 in 10 homes tested in North Dakota were at or above the EPA action level of 4 pCi/L.

5,054 homes tested, 2008–2017
  • Below 2 pCi/L: 18%
  • 2 to 4 pCi/L: 23%
  • 4 pCi/L or more: 59%
The line marks the EPA action level, 4 pCi/L.

The EPA puts 53 of North Dakota's 53 counties in Zone 1, its highest radon category, 0 in Zone 2 and 0 in Zone 3.

Every county in North Dakota

Sorted by the share of homes tested at or above 4 pCi/L. Select a county for local details and costs.

CountyHomes testedAt or above 4MedianEPA zone
Sioux County2 tests––1
Emmons County
86%7.1 pCi/L1
Billings County12 tests––1
Pembina County
83%9.3 pCi/L1
Adams County9 tests––1
Walsh County
80%9.8 pCi/L1
Kidder County19 tests––1
Benson County
77%6.2 pCi/L1
Ramsey County
77%6.9 pCi/L1
Grand Forks County
76%8.8 pCi/L1
Sargent County18 tests––1
Dunn County
74%7.1 pCi/L1
Grant County19 tests––1
Stutsman County
74%5.8 pCi/L1
Renville County9 tests––1
McIntosh County
72%7.0 pCi/L1
Bowman County
71%5.8 pCi/L1
Golden Valley County6 tests––1
LaMoure County
71%5.2 pCi/L1
Slope County4 tests––1
Barnes County
68%5.6 pCi/L1
Dickey County
67%4.8 pCi/L1
Mountrail County
67%7.3 pCi/L1
Oliver County9 tests––1
McHenry County
64%5.3 pCi/L1
Bottineau County
64%5.7 pCi/L1
Burke County8 tests––1
Mercer County
64%5.7 pCi/L1
McLean County
63%5.6 pCi/L1
Nelson County11 tests––1
Hettinger County15 tests––1
Stark County
62%5.1 pCi/L1
Ransom County
62%5.8 pCi/L1
Foster County
61%4.5 pCi/L1
Cass County
58%4.7 pCi/L1
McKenzie County
56%4.8 pCi/L1
Towner County18 tests––1
Griggs County9 tests––1
Sheridan County9 tests––1
Morton County
53%4.2 pCi/L1
Traill County
51%4.1 pCi/L1
Burleigh County
51%4.0 pCi/L1
Cavalier County
50%3.9 pCi/L1
Divide County11 tests––1
Logan County10 tests––1
Pierce County
49%3.8 pCi/L1
Wells County
48%3.8 pCi/L1
Rolette County
46%3.4 pCi/L1
Richland County
43%3.6 pCi/L1
Ward County
43%3.3 pCi/L1
Williams County
34%2.9 pCi/L1
Eddy County5 tests––1
Steele County2 tests––1

"–" means fewer than 20 tests or no lab data, too few for a reliable figure.

Sources

Last updated October 2026. How we calculate these numbers.