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Radon Levels in Divide County, North Dakota

EPA puts Divide County in Zone 1, its highest radon zone, and only 14 radon tests from it are on file with CDC (2008 to 2017, laboratory totals). Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

How to test this homeFind a certified tester

  • Highest bordering

    75.7%

    Sheridan County

    Sheridan
    75.7%
    Williams
    33.8%

    2 of 3 neighbours have 30+ tests, 2008 to 2017

  • Nearest county

    33.8%

    Williams County, 33 miles

    Williams
    33.8%
    ND
    59.3%

    Share at 4+ pCi/L, 204 tests, 2008 to 2017

  • Ground above low

    100.0%

    Level with ND

    Divide
    100.0%
    ND
    100.0%

    Share of land USGS rates moderate or high potential

  • Tests reported

    23

    Too few for a share

    Divide
    23
    Needed
    30

    2005 to 2014, laboratory

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

Read a result for Divide County

Starts at EPA's action level

4.0pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 4.0 pCi/L

At or above 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 4 and aboveEPA says fix it

This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher.

Interpret this readingWhat a fix costs

The data

Divide County, At a glance

Divide County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Divide County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

USGS geologic potential: High across 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Divide County, 2008 to 2017, laboratory

CDC holds 14 reported tests for Divide County over the 2008 to 2017 laboratory totals, with a median of 4.6 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Divide County beside the counties around it is how this page reads it.

What these figures count

Only 14 tests were reported to CDC for Divide County over 2008 to 2017 (laboratory totals), and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.

Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

How to read these figures

Divide County, Compared

Divide County radon figures, compared

Calculated by Radon411

CDC's largest figure for Divide County rests on 23 tests over the 2005 to 2014 laboratory totals, 10 of them at or above 4 pCi/L, so each test moves its share by 4.3 points and no rank or comparison is drawn from it. Results reached as high as 11.7 pCi/L, with a middle value of 3.5 pCi/L.

Of the counties bordering it, 2 have a figure over the 2008 to 2017 laboratory totals: Sheridan County, MT reported the largest share at or above 4 pCi/L, 75.7%, and Williams County the smallest, 33.8%. Farther out, Mountrail County (67 miles away) at 66.7%, McKenzie County (74 miles away) at 56.1% and Ward County (98 miles away) at 43.0% have figures too. Pooled across 53 North Dakota counties, 59.3% of reported tests reached that level; across every county in the country with a figure, 35.7%.

Statewide for the same period, Pembina County reported the highest share (82.5%) and Williams County the lowest (33.8%). EPA's 1993 map puts Divide County in Zone 1, the map's highest label: a predicted county average above 4 pCi/L. USGS geology rates 100% of the county's land high radon potential.

North Dakota, the United States and the counties around Divide County, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedian
North Dakota, pooled53 counties, pooled6,60759.3%Not pooled
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled
Pembina Countyhighest in the state5782.5%9.3 pCi/L
Richland Countylowest in the state9343.0%3.6 pCi/L
Sheridan County, MTborders it7075.7%6.5 pCi/L
Burke County, NDborders it1163.6%7.8 pCi/L
Williams County, NDborders it20433.8%2.9 pCi/L
The nearest North Dakota counties to Divide County with 30 or more tests, 2008 to 2017, laboratory
CountyDistanceTestsAt or above 4 pCi/LMedian
Williams County33 mi20433.8%2.9 pCi/L
Mountrail County67 mi4866.7%7.3 pCi/L
McKenzie County74 mi4156.1%4.8 pCi/L
Ward County98 mi44643.0%3.3 pCi/L
Dunn County108 mi3574.3%7.1 pCi/L
Bottineau County121 mi11164.0%5.7 pCi/L
Mercer County129 mi8563.5%5.7 pCi/L
McLean County130 mi9563.2%5.6 pCi/L
Divide County ten-year laboratory totals, against North Dakota's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestNorth Dakota, pooledChange from the row before
2008 to 20171450.0%4.6 pCi/L10.9 pCi/L59.3%−3.3 points
2007 to 20161553.3%5.6 pCi/L11.7 pCi/L58.7%+3.3 points
2006 to 20152250.0%4.5 pCi/L11.7 pCi/L56.3%+6.5 points
2005 to 20142343.5%3.5 pCi/L11.7 pCi/L54.0%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Divide County, Geology

The ground under Divide County

Predicted

USGS's geologic map puts all of Divide County's mapped land in one class: high radon potential. All of it lies in the area the map calls Great Plains (Glaciated), to which USGS gives a radon index of 13, in the high band (12 to 17).

USGS's geologic areas under Divide County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Great Plains (Glaciated)Glacial deposits derived from Cretaceous shales containing higher than average amounts of uranium.High13100%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Divide County beside the ground around it

On high-potential ground Divide County is close to North Dakota as a whole: 100% of its land against 98.9%. Of the 3 counties that border it, none has as large a share of high-potential ground; Burke County comes nearest at 100%.

Share of land by USGS radon potential: Divide County, the 3 counties bordering it and North Dakota
AreaEPA zoneLow potentialModerate potentialHigh potential
Divide CountyZone 1NoneNone100%
Williams CountyZone 1NoneNone100%
Burke CountyZone 1NoneNone100%
Sheridan County, MTZone 1NoneNone100%
North Dakota53 counties, pooled by land areaVariesNone1.1%98.9%

The map rates the ground, not the air in any home.

Local help

Divide County, Local resources

Radon testing and mitigation in Divide County

What North Dakota's program says
Phone
701-328-5166
Email
jOtto@nd.gov

What it means

Divide County, Questions

Questions about radon in Divide County

Are radon levels high in Divide County?

Over the 2008 to 2017 laboratory totals, 50.0% of the radon tests reported to CDC for Divide County, North Dakota were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.6 pCi/L. Of the counties bordering it, 2 have a figure over the 2008 to 2017 laboratory totals: Sheridan County, MT reported the largest share at or above 4 pCi/L, 75.7%, and Williams County the smallest, 33.8%.

Which counties border Divide County?

Divide County borders 3 counties: Williams County, ND, Burke County, ND and Sheridan County, MT.

Products

Divide County, Products

Testing a home in Divide County

No CDC figure names Divide County; the nearest county with one, Williams County (33 miles away), reported 33.8% of its tests at or above 4 pCi/L over the 2008 to 2017 laboratory totals, the only reading nearby until a test of this home. In Zone 1 the year-round level in Divide County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.

Test kits and monitors3

See every kit and monitor

Divide County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Divide County

Explore

Divide County, Bordering counties

Counties bordering Divide County

Calculated by Radon411

Divide County, Cities and towns

Cities and towns in Divide County

About 2,110 people live in Divide County by the Census Bureau's estimate for July 1, 2025, 92 fewer than in 2020 (−4.2%). Spread over its land, that is 1.7 people to the square mile. Its largest town, Crosby, has 1,027 residents, 48.7% of the total. Together its 4 incorporated places hold 57.2% of those residents; the other 42.8% live outside any of them. CDC's 23 reported tests for 2005 to 2014 work out to 10.9 per 1,000 residents (2025 estimate), close to North Dakota's 8.2.

From Crosby to Ambrose, CDC publishes no figure by town: each reads Divide County's.

The cities and towns in Divide County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Crosby1,027−4.4%48.7%
Noonan133−3.6%6.3%
Fortuna30−3.2%1.4%
Ambrose16−5.9%0.8%

4 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025).

Divide County, Homes

Homes in Divide County

Divide County is a place of houses on their own lots: 81% of its 1,373 homes are detached single-family houses, against 57% across North Dakota. The homes are older than North Dakota's as a whole: half were built before 1962 (1981 for North Dakota), and 48% date from before 1960. Owners live in 78% of the occupied homes (North Dakota: 63%), so for most households a test and a fix are their own to order.

Homes in Divide County, North Dakota, 2019 to 2023
HomesDivide CountyNorth Dakota
Housing units1,373374,866
Detached houses81%57%
In buildings of 5 or more6%25%
Mobile homes10%7%
Built before 196048%24%
Built since 200020%31%
Middle year built19621981
Owner-occupied78%63%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.