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Radon Levels in Grand Forks County, North Dakota

EPA puts Grand Forks County in Zone 1, its highest radon zone, and high results are common there: 75.9% of the 680 radon tests reported to CDC (2008 to 2017, laboratory totals) came back at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

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  • Share at 4+ pCi/L

    75.9%

    16.6 pts above ND

    Grand Forks
    75.9%
    ND
    59.3%

    680 tests, 2008 to 2017

  • Median result

    8.8pCi/L

    Action level reached

    Grand Forks
    8.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    680

    3rd of 29 by tests

    Grand Forks
    680
    Burleigh
    1,558

    Reported to CDC before any fix, 2008 to 2017

  • 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

  • Rank in ND

    5 of 29

    Top quarter

    Grand Forks
    75.9%
    Pembina
    82.5%

    By share, of 29 with 30+ tests

Read a result for Grand Forks County

Starts at Grand Forks County's median, 8.8 pCi/L

8.8pCi/L

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

EPA’s reading of 8.8 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. Grand Forks County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Grand Forks County, At a glance

Grand Forks County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Grand Forks 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 Grand Forks County, 2008 to 2017, laboratory

Reported results by concentration band, Grand Forks County, 2008 to 2017, laboratory
Under 2 pCi/L: 14%2 to 4 pCi/L: 10%4 pCi/L and above: 76%

Of 680 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Grand Forks County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L9313.7%
2 to 4 pCi/L7110.4%
4 pCi/L and above51675.9%
What these figures count

These are the 680 tests reported to CDC for Grand Forks County over 2008 to 2017 (laboratory totals), many from homes being sold or already suspected of a problem: they describe the county's reported tests, not 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

Grand Forks County, Compared

Grand Forks County radon figures, compared

Calculated by Radon411

More than half: 75.9% of the 680 radon tests reported to CDC for Grand Forks County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 5th of 29 North Dakota counties with 30 or more tests for the same period. That is 16.6 points above the 59.3% pooled from 53 North Dakota counties.

The median result, 8.8 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 215.6 pCi/L. The rest split 13.7% under 2 pCi/L and 10.4% from 2 to 4 (North Dakota: 18.3% and 22.4%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 75.9% share point the same way here.

1 of its 4 bordering counties with figures ran higher, led by Walsh County at 79.5%; Traill County reported 51.4%. Statewide for the same period, Pembina County reported the highest share (82.5%) and Williams County the lowest (33.8%).

CDC's ten-year totals for Grand Forks County went from 436 tests (2005 to 2014) to 680 (2008 to 2017), the share going from 73.9% to 75.9%.

Nationally, every county with a figure for the same period pools to 35.7%; Grand Forks County sits 40.2 points above it. CDC also counts 63 tests taken after mitigation in Grand Forks County for the same period: tests in homes where a fix was already in.

Grand Forks County against North Dakota, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Grand Forks County
Grand Forks County68075.9%8.8 pCi/LThis county
North Dakota, pooled53 counties, pooled6,60759.3%Not pooled−16.6 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−40.2 points
Pembina Countyhighest in the state5782.5%9.3 pCi/L+6.6 points
Williams Countylowest in the state20433.8%2.9 pCi/L−42.1 points
Walsh County, NDborders it13279.5%9.8 pCi/L+3.6 points
Polk County, MNborders it39770.8%6.7 pCi/L−5.1 points
Nelson County, NDborders it1963.2%5.7 pCi/L−12.7 points
Marshall County, MNborders it9955.6%5.4 pCi/L−20.3 points
Traill County, NDborders it3751.4%4.1 pCi/L−24.5 points
Steele County, NDborders it10.0%2.0 pCi/L−75.9 points
Where Grand Forks County's reported results fell, 2008 to 2017, laboratory, beside North Dakota and the United States
ResultGrand Forks County testsGrand Forks County shareNorth Dakota shareU.S. shareAgainst North Dakota
Under 2 pCi/L9313.7%18.3%39.6%−4.6 points
2 to 4 pCi/L7110.4%22.4%24.7%−12.0 points
4 pCi/L and above51675.9%59.3%35.7%+16.6 points
Grand Forks County ranked among the 29 North Dakota counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Pembina County1 of 295782.5%9.3 pCi/L
Walsh County2 of 2913279.5%9.8 pCi/L
Benson County3 of 293177.4%6.2 pCi/L
Ramsey County4 of 2913476.9%6.9 pCi/L
Grand Forks County5 of 2968075.9%8.8 pCi/L
Dunn County6 of 293574.3%7.1 pCi/L
Stutsman County7 of 2935173.5%5.8 pCi/L
McIntosh County8 of 293271.9%7.0 pCi/L
Bowman County9 of 293571.4%5.8 pCi/L
LaMoure County10 of 294470.5%5.2 pCi/L
Barnes County11 of 298367.5%5.6 pCi/L
Grand Forks 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 201768075.9%8.8 pCi/L215.6 pCi/L59.3%+0.2 points
2007 to 201664575.7%8.7 pCi/L101.1 pCi/L58.7%+0.9 points
2006 to 201555174.8%8.6 pCi/L101.1 pCi/L56.3%+0.9 points
2005 to 201443673.9%8.0 pCi/L101.1 pCi/L54.0%First on file

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

Grand Forks County, Geology

The ground under Grand Forks County

Predicted

USGS's geologic map puts all of Grand Forks County's mapped land in one class: high radon potential. The map puts 85.1% of Grand Forks County in the area it calls Glacial Lakes and 14.8% in Great Plains (Glaciated). USGS gives the first a radon index of 14 and the second 13, both in the high band (12 to 17).

USGS's geologic areas under Grand Forks County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Glacial LakesSilt and clay deposits of Glacial Lake Agassiz derived from Cretaceous shales containing higher than average amounts of uranium.High1485.1%
Great Plains (Glaciated)Glacial deposits derived from Cretaceous shales containing higher than average amounts of uranium.High1314.8%

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

Grand Forks County beside the ground around it

On high-potential ground Grand Forks County is close to North Dakota as a whole: 100% of its land against 98.9%. Of the 6 counties that border it, none has as large a share of high-potential ground; Nelson County comes nearest at 100%.

Share of land by USGS radon potential: Grand Forks County, the 6 counties bordering it and North Dakota
AreaEPA zoneLow potentialModerate potentialHigh potential
Grand Forks CountyZone 1NoneNone100%
Walsh CountyZone 1NoneNone100%
Steele CountyZone 1NoneNone100%
Nelson CountyZone 1NoneNone100%
Traill CountyZone 1NoneNone100%
Polk County, MNZone 1None3.5%96.5%
Marshall County, MNZone 1None32.7%67.3%
North Dakota53 counties, pooled by land areaVariesNone1.1%98.9%

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

Local help

Grand Forks County, Local resources

Radon testing and mitigation in Grand Forks County

Listed radon businesses with an address in Grand Forks County:

Listed radon professionals by town: Grand Forks

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

What it means

Grand Forks County, Questions

Questions about radon in Grand Forks County

Are radon levels high in Grand Forks County?

Over the 2008 to 2017 laboratory totals, 75.9% of the radon tests reported to CDC for Grand Forks County, North Dakota were at or above 4 pCi/L, and the median reported pre-mitigation result was 8.8 pCi/L. Of 29 North Dakota counties with 30 or more tests for the same period, 4 reported a higher share; pooled, the state comes to 59.3%.

Which counties border Grand Forks County?

Grand Forks County borders 6 counties: Walsh County, ND, Steele County, ND, Nelson County, ND, Traill County, ND, Polk County, MN and Marshall County, MN.

Products

Grand Forks County, Products

Testing a home in Grand Forks County

In Grand Forks County, 75.9% of 680 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 59.3% pooled across North Dakota. In Zone 1 the year-round level in Grand Forks 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

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

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Grand Forks County, Bordering counties

Counties bordering Grand Forks County

Calculated by Radon411

Grand Forks County, Cities and towns

Cities and towns in Grand Forks County

The Census Bureau estimates 74,501 residents in Grand Forks County for July 1, 2025, 1,359 more than in 2020 (+1.9%). That works out to 52 people per square mile of land. Grand Forks alone is home to 60,365 of them, 81.0% of the total. CDC's 680 reported tests for 2008 to 2017 work out to 9.1 per 1,000 residents (2025 estimate), close to North Dakota's 8.3.

From Grand Forks to Inkster, CDC publishes no figure by town: each reads Grand Forks County's.

The cities and towns in Grand Forks County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Grand Forks60,365+2.0%81.0%
Larimore1,359+7.9%1.8%
Thompson1,100+0.4%1.5%
Northwood959−1.9%1.3%
Emerado452+1.8%0.6%
Manvel368−1.1%0.5%
Reynoldsextends beyond Grand Forks County273+1.5%Counted whole
Gilby246+0.8%0.3%
Niagara43LevelUnder 0.1%
Inkster38LevelUnder 0.1%

10 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). A place that extends beyond Grand Forks County is counted whole, so it has no share.

Grand Forks County, Homes

Homes in Grand Forks County

Grand Forks County has 33,736 homes, and many share a building: 36% are in buildings of five or more, 44% are detached houses, against 57% across North Dakota. Half of its homes were built before 1981, close to North Dakota's 1981: 22% date from before 1960 and 29% from 2000 or later. 52% of occupied homes are lived in by their owner (North Dakota: 63%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Grand Forks County, North Dakota, 2019 to 2023
HomesGrand Forks CountyNorth Dakota
Housing units33,736374,866
Detached houses44%57%
In buildings of 5 or more36%25%
Mobile homes4%7%
Built before 196022%24%
Built since 200029%31%
Middle year built19811981
Owner-occupied52%63%

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