Radon in North Dakota: radon map by county
EPA's Map of Radon Zones puts 53 of North Dakota's 53 counties in Zone 1 (predicted average indoor radon above 4 pCi/L), 0 in Zone 2 and 0 in Zone 3. Of 5,054 building tests that radon laboratories reported for 2008 to 2017, 58.9% were at or above EPA's 4 pCi/L action level, against 36.5% nationally (the highest of 42 states with 1,000+ tests). The highest county share is Emmons County (86.2% of 20 tests).
Radon by county in North Dakota
| County | EPA zone | Lab tests | Median | 4+ pCi/L |
|---|---|---|---|---|
| Adams County | Zone 1 | 9 | 12.7 | 80% |
| Barnes County | Zone 1 | 67 | 5.6 | 67.5% |
| Benson County | Zone 1 | 20 | 6.2 | 77.4% |
| Billings County | Zone 1 | 12 | 11.0 | 85% |
| Bottineau County | Zone 1 | 70 | 5.7 | 64% |
| Bowman County | Zone 1 | 22 | 5.8 | 71.4% |
| Burke County | Zone 1 | 8 | 7.8 | 63.6% |
| Burleigh County | Zone 1 | 1,255 | 4.0 | 51.1% |
| Cass County | Zone 1 | 725 | 4.7 | 57.5% |
| Cavalier County | Zone 1 | 21 | 3.9 | 50% |
| Dickey County | Zone 1 | 57 | 4.8 | 67.1% |
| Divide County | Zone 1 | 11 | 4.6 | 50% |
| Dunn County | Zone 1 | 23 | 7.1 | 74.3% |
| Eddy County | Zone 1 | 5 | 0.9 | 12.5% |
| Emmons County | Zone 1 | 20 | 7.1 | 86.2% |
| Foster County | Zone 1 | 25 | 4.5 | 61.3% |
| Golden Valley County | Zone 1 | 6 | 6.2 | 71.4% |
| Grand Forks County | Zone 1 | 522 | 8.8 | 75.9% |
| Grant County | Zone 1 | 19 | 7.4 | 73.9% |
| Griggs County | Zone 1 | 9 | 5.0 | 54.5% |
| Hettinger County | Zone 1 | 15 | 5.8 | 62.5% |
| Kidder County | Zone 1 | 19 | 7.3 | 79.3% |
| LaMoure County | Zone 1 | 32 | 5.2 | 70.5% |
| Logan County | Zone 1 | 10 | 3.7 | 50% |
| McHenry County | Zone 1 | 22 | 5.3 | 64.3% |
| McIntosh County | Zone 1 | 24 | 7.0 | 71.9% |
| McKenzie County | Zone 1 | 29 | 4.8 | 56.1% |
| McLean County | Zone 1 | 69 | 5.6 | 63.2% |
| Mercer County | Zone 1 | 70 | 5.7 | 63.5% |
| Morton County | Zone 1 | 231 | 4.2 | 53.4% |
| Mountrail County | Zone 1 | 25 | 7.3 | 66.7% |
| Nelson County | Zone 1 | 11 | 5.7 | 63.2% |
| Oliver County | Zone 1 | 9 | 6.0 | 66.7% |
| Pembina County | Zone 1 | 41 | 9.3 | 82.5% |
| Pierce County | Zone 1 | 36 | 3.8 | 48.7% |
| Ramsey County | Zone 1 | 89 | 6.9 | 76.9% |
| Ransom County | Zone 1 | 116 | 5.8 | 61.6% |
| Renville County | Zone 1 | 9 | 6.4 | 72.7% |
| Richland County | Zone 1 | 80 | 3.6 | 43% |
| Rolette County | Zone 1 | 20 | 3.4 | 46.2% |
| Sargent County | Zone 1 | 18 | 7.2 | 75% |
| Sheridan County | Zone 1 | 9 | 4.2 | 54.5% |
| Sioux County | Zone 1 | 2 | 9.3 | 100% |
| Slope County | Zone 1 | 4 | 10.3 | 70% |
| Stark County | Zone 1 | 242 | 5.1 | 62.4% |
| Steele County | Zone 1 | 2 | 2.0 | 0% |
| Stutsman County | Zone 1 | 247 | 5.8 | 73.5% |
| Towner County | Zone 1 | 18 | 5.6 | 56% |
| Traill County | Zone 1 | 28 | 4.1 | 51.4% |
| Walsh County | Zone 1 | 89 | 9.8 | 79.5% |
| Ward County | Zone 1 | 322 | 3.3 | 43% |
| Wells County | Zone 1 | 60 | 3.8 | 48.1% |
| Williams County | Zone 1 | 150 | 2.9 | 33.8% |
Lab tests: buildings tested by radon laboratories, 2008 to 2017; median in pCi/L; “4+ pCi/L” is the share of tests at or above EPA's action level. n/a: no value on file (no tests, or too few to report).
What the zones mean
Zone 1 counties have a predicted average indoor radon screening level above 4 pCi/L, Zone 2 from 2 to 4 pCi/L and Zone 3 below 2 pCi/L. The prediction is from 1993 indoor measurements, geology, aerial radioactivity, soils and foundation types. EPA: “This map should not be used to determine if individual homes need to be tested.” EPA recommends fixing a home at 4 pCi/L or more and considering a fix between 2 and 4 pCi/L, because there is no known safe level of exposure.
Radon in North Dakota: questions
What radon zone is North Dakota?
EPA's 1993 map does not give states one zone; it zones each county. In North Dakota, 53 counties are Zone 1, 0 Zone 2 and 0 Zone 3. EPA says the map "should not be used to determine if individual homes need to be tested".
Which North Dakota counties have the highest radon levels?
By the share of laboratory tests at or above 4 pCi/L for 2008 to 2017 (counties with 20 or more tests): Emmons County 86.2% (median 7.1 pCi/L, 20 tests); Pembina County 82.5% (median 9.3 pCi/L, 41 tests); Walsh County 79.5% (median 9.8 pCi/L, 89 tests); Benson County 77.4% (median 6.2 pCi/L, 20 tests); Ramsey County 76.9% (median 6.9 pCi/L, 89 tests).
How common is high radon in North Dakota?
58.9% of the 5,054 tests in the laboratory data for North Dakota (2008 to 2017) were at or above 4 pCi/L; the national share was 36.5%. Buildings are tested by choice, often because of a sale or a concern, so the share describes the tests on file, not every home.
Should I test for radon in North Dakota?
Yes. EPA recommends testing every home no matter where it is, fixing it at 4 pCi/L or more and considering a fix between 2 and 4 pCi/L, because there is no known safe level of radon exposure.
States bordering North Dakota
Other free hazard lookups
- Radon by county and ZIP codeEPA radon zone and the radon test results on file for any county, ZIP code or address.
- Fault lines near an addressUSGS-mapped earthquake faults within 5 miles, their age and slip rate, and the USGS seismic hazard value.
- Power lines near an addressHigh-voltage transmission lines within 1 mile from federal maps, with voltage and distance.
- Flood zone lookupThe FEMA flood zone mapped at any US address. Not an official flood zone determination.
- Superfund sites near an addressThe nearest EPA Superfund (NPL) sites and their status.
All of these, plus wetlands, FEMA hazard ratings and the federal contamination lists, are in the Environmental Records Report for any US address ($29).
Superfund sites in North Dakota · Radon map of every state
Data compiled 2026-10-20. County-level screening information, not a radon measurement of any building.