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Radon Levels in Cass County, Minnesota

EPA puts Cass County in Zone 2, its middle radon zone, and 25.5% of its 106 reported radon tests (2023) were 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    25.5%

    9.1 pts below MN

    Cass
    25.5%
    Minnesota
    34.6%

    106 tests, 2023

  • Median result

    2.3pCi/L

    Below action level

    Cass
    2.3 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    106

    32nd of 62 by tests

    Cass
    106
    Hennepin
    6,545

    Reported to CDC before any fix, 2023

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    EPA predicts 2 to 4 pCi/L indoors

  • Rank in Minnesota

    52 of 62

    Lowest quarter

    Cass
    25.5%
    Renville
    75.7%

    By share, of 62 with 30+ tests

Read a result for Cass County

Starts at Cass County's median, 2.3 pCi/L

2.3pCi/L

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

EPA’s reading of 2.3 pCi/L

Between 2 and 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 between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Cass County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Cass County, At a glance

Cass County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Cass County is a county: EPA's forecast for it as a whole is an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³). It describes no single address, and homes above EPA's are found in every zone, this one included.

USGS geologic potential: Moderate across 55% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Cass County, 2023

Share of reported tests at or above 4 pCi/L, by year, Cass County
Share of reported tests at or above 4 pCi/L, by year, Cass County
YearShare of reported tests at or above 4 pCi/L
201433.9%
201530.5%
201628.0%
201728.3%
201826.9%
201932.5%
202035.9%
202129.9%
202219.4%
202325.5%

2023: 25.5%. Across these years the share ran from 19.4% to 35.9%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 106 tests reported to CDC for Cass County over 2023, 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: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).

How to read these figures

Cass County, Compared

Cass County radon figures, compared

Calculated by Radon411

Cass County's 106 reported tests in 2023 had a middle value of 2.3 pCi/L and a maximum of 14.9 pCi/L, and 25.5% reached 4 pCi/L. Minnesota as a whole (86 Minnesota counties, pooled) comes to 34.6%: 9.1 points higher than here.

Among its state's counties it ranks 52nd of 62 Minnesota counties with 30 or more tests for the same period. Statewide for the same period, Renville County reported the highest share (75.7%) and Lake County the lowest (3.8%).

Below the action level, 48 tests (45.3%) came in under 2 pCi/L, against 36.6% statewide, and 31 tests (29.2%) fell between 2 and 4, against 28.9% statewide. The busiest year on file was 2015, with 197 tests reported; the quietest, 2019, had 40.

EPA's 1993 zone map puts Cass County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 55% of the county's land moderate radon potential.

Next door, the shares run from 23.8% in Todd County to 46.0% in Hubbard County, with Todd County below Cass County. Over 10 years of annual figures the share fell 8.4 points, from 33.9% in 2014 to 25.5% in 2023; its peak was 35.9% in 2020.

Share of reported tests at or above 4 pCi/L by year, Cass County against Minnesota2014 to 2023, years with 30 or more tests: Cass County 33.9% to 25.5%, the state's pooled share 34.6% in 2023.
Cass CountyMinnesota, pooled
Share of reported tests at or above 4 pCi/L by year, Cass County against Minnesota: data table
YearTestsCass County, at or above 4 pCi/LMinnesota, pooled
201412433.9%42.9%
201519730.5%43.6%
201613228.0%37.0%
201710628.3%38.2%
201811926.9%38.3%
20194032.5%36.1%
202010335.9%31.8%
20217729.9%33.1%
202212419.4%31.6%
202310625.5%34.6%
Cass County against Minnesota, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Cass County
Cass County10625.5%2.3 pCi/LThis county
Minnesota, pooled86 counties, pooled22,44934.6%Not pooled+9.1 points
United States, pooled642 counties, pooled128,74033.4%Not pooled+7.9 points
Renville Countyhighest in the state3775.7%6.3 pCi/L+50.2 points
Lake Countylowest in the state783.8%1.3 pCi/L−21.7 points
Hubbard County, MNborders it6346.0%3.8 pCi/L+20.5 points
Beltrami County, MNborders it5440.7%3.0 pCi/L+15.2 points
Wadena County, MNborders it1540.0%2.8 pCi/L+14.5 points
Aitkin County, MNborders it3138.7%3.1 pCi/L+13.2 points
Morrison County, MNborders it6235.5%3.0 pCi/L+10.0 points
Crow Wing County, MNborders it17730.5%2.7 pCi/L+5.0 points
Itasca County, MNborders it13726.3%1.9 pCi/L+0.8 points
Todd County, MNborders it6323.8%2.0 pCi/L−1.7 points
Where Cass County's reported results fell, 2023, beside Minnesota and the United States
ResultCass County testsCass County shareMinnesota shareU.S. shareAgainst Minnesota
Under 2 pCi/L4845.3%36.6%41.4%+8.7 points
2 to 4 pCi/L3129.2%28.9%25.2%+0.3 points
4 pCi/L and above2725.5%34.6%33.4%−9.1 points
Cass County ranked among the 62 Minnesota counties with 30 or more tests, by share at or above 4 pCi/L, 2023
CountyRankTestsAt or above 4 pCi/LMedian
Carver County47 of 6248934.6%2.8 pCi/L
Blue Earth County48 of 6239232.7%2.2 pCi/L
Hennepin County49 of 626,54532.0%2.7 pCi/L
Crow Wing County50 of 6217730.5%2.7 pCi/L
Itasca County51 of 6213726.3%1.9 pCi/L
Cass County52 of 6210625.5%2.3 pCi/L
Todd County53 of 626323.8%2.0 pCi/L
Ramsey County54 of 622,21323.5%2.2 pCi/L
Benton County55 of 624323.3%2.2 pCi/L
Isanti County56 of 626622.7%2.0 pCi/L
Sherburne County57 of 6235121.7%1.8 pCi/L
Cass County radon tests by year, against Minnesota's pooled share
YearTestsAt or above 4 pCi/LMedianHighestMinnesota, pooledChange from the row before
202310625.5%2.3 pCi/L14.9 pCi/L34.6%+6.1 points
202212419.4%2.1 pCi/L20.4 pCi/L31.6%−10.5 points
20217729.9%2.9 pCi/L18.0 pCi/L33.1%−6.0 points
202010335.9%2.8 pCi/L9.6 pCi/L31.8%+3.4 points
20194032.5%2.6 pCi/L8.2 pCi/L36.1%+5.6 points
201811926.9%2.1 pCi/L14.7 pCi/L38.3%−1.4 points
201710628.3%2.8 pCi/L10.6 pCi/L38.2%+0.3 points
201613228.0%2.4 pCi/L11.4 pCi/L37.0%−2.5 points
201519730.5%2.5 pCi/L18.9 pCi/L43.6%−3.4 points
201412433.9%3.2 pCi/L14.2 pCi/L42.9%First on file

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

Cass County, State data

Minnesota's own radon test data

Measured

What Minnesota's own agencies publish about radon tests in Cass County, with their period. These are not CDC's figures and are never added to them.

MeasuredState figures, not CDC's

What the Minnesota Department of Health reports for Cass County

Radon Testing (MN Public Health Data Access Portal): home radon tests reported voluntarily by private laboratories and licensed radon measurement professionals, counted by property. Period: 2016-2025.

Share with one or more tests at or above 4 pCi/L

31.6%

236 properties tested with one or more tests at or above 4 pCi/L

Median result

2.7 pCi/L

Average result

3.2 pCi/L

Tests behind these figures

75 properties tested a year on average

  • MDH says these data do not include all of the radon tests conducted in Minnesota.
  • Post-mitigation tests are excluded from the averages and the median; the percentages use each property's highest test.
  • Each home is unique and can have very different results than a neighbor's home; the only way to know is to test.
  • These figures describe tests reported to the Minnesota Department of Health in this area. They count a different set of tests than CDC's figures and are not a reading of any one home.

Measured: Minnesota Department of Health data, 2016-2025.

Cass County, Geology

The ground under Cass County

Predicted

USGS's geologic map splits Cass County: 54.7% of its land is moderate radon potential and 45.3% high. The map puts 45.3% of Cass County in the area it calls Central Lowland-Western Lake Section and 28.5% in Superior Upland/Central Lowland-Western Lake Section, with one smaller area beside them. USGS gives the first a radon index of 14, in the high band (12 to 17), and the second 10, in the moderate band (9 to 11).

USGS's geologic areas under Cass County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Central Lowland-Western Lake SectionSandy calcareous till derived from carbonate rocks.High1445.3%
Superior Upland/Central Lowland-Western Lake SectionGlacial deposits derived primarily from volcanic rock.Moderate1028.5%
Lake Agassiz Plain/Central Lowland-Western Lake SectionSilty and clayey glacial deposits and lake deposits.Moderate1026.2%

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

Cass County beside the ground around it

Minnesota as a whole has more high-potential ground than Cass County: 61.1% of its land, against 45.3% here. Of the 8 counties that border it, 3 have more high-potential ground, Wadena County the most at 99.1%.

Share of land by USGS radon potential: Cass County, the 8 counties bordering it and Minnesota
AreaEPA zoneLow potentialModerate potentialHigh potential
Cass CountyZone 2None54.7%45.3%
Crow Wing CountyZone 2None99.0%1.0%
Hubbard CountyZone 1None1.0%99.0%
Aitkin CountyZone 2None100%None
Wadena CountyZone 1None0.9%99.1%
Itasca CountyZone 2None100%None
Morrison CountyZone 2None97.7%2.3%
Todd CountyZone 1None22.7%77.3%
Beltrami CountyZone 2None94.7%5.3%
Minnesota87 counties, pooled by land areaVariesNone38.9%61.1%

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

Local help

Cass County, Local resources

Radon testing and mitigation in Cass County

What Minnesota's program says
Phone
651-201-4601
Email
health.indoorair@state.mn.us
Licensing of radon professionals
The Radon Licensing Act requires anyone who performs a radon test or radon mitigation, in a building they do not own or lease, must be licensed by MDH.
Disclosure when a home is sold or rented
The Minnesota Radon Awareness Act requires specific disclosure and education be provided to potential home buyers during residential real estate transactions in Minnesota.

What it means

Cass County, Questions

Questions about radon in Cass County

Are radon levels high in Cass County?

In 2023, 25.5% of the radon tests reported to CDC for Cass County, Minnesota were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.3 pCi/L. Of 62 Minnesota counties with 30 or more tests for the same period, 51 reported a higher share; pooled, the state comes to 34.6%.

Which counties border Cass County?

Cass County borders 8 counties: Crow Wing County, Hubbard County, Aitkin County, Wadena County, Itasca County, Morrison County, Todd County and Beltrami County.

Products

Cass County, Products

Testing a home in Cass County

In Cass County, 25.5% of 106 tests reported to CDC in 2023 reached 4 pCi/L, against 34.6% pooled across Minnesota. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Cass County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Cass County homes, compared

Explore

Cass County, Bordering counties

Counties bordering Cass County

Calculated by Radon411

Cass County, Cities and towns

Cities and towns in Cass County

The Census Bureau estimates 31,430 residents in Cass County for July 1, 2025, 1,278 more than in 2020 (+4.2%). That works out to 16 people per square mile of land. No town dominates: East Gull Lake, the largest, has 1,184 residents, 3.8% of the total. CDC's 106 reported tests for 2023 work out to 3.4 per 1,000 residents (2025 estimate), close to Minnesota's 3.9.

From East Gull Lake to Boy River, CDC publishes no figure by town: each reads Cass County's.

The 12 largest cities and towns in Cass County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
East Gull Lake1,184+20.0%3.8%
Lake Shore1,127+5.5%3.6%
Walker976−0.1%3.1%
Pine River911−0.4%2.9%
Motleyextends beyond Cass County688+1.6%Counted whole
Cass Lake677Level2.2%
Pillager541+6.1%1.7%
Remer380+0.5%1.2%
Hackensack306+4.1%1.0%
Backus264−1.9%0.8%
Longville157−0.6%0.5%
Bena156+4.7%0.5%
  • Chickamaw Beach
  • Federal Dam
  • Boy River

15 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Cass County is counted whole, so it has no share.

Cass County, Homes

Homes in Cass County

Cass County is a place of houses on their own lots: 85% of its 24,294 homes are detached single-family houses, against 66% across Minnesota. Much of Cass County is recent building: 31% of its homes have gone up since 2000 and the middle year built is 1990, against 1978 for Minnesota. Owners live in 85% of the occupied homes (Minnesota: 72%), so for most households a test and a fix are their own to order.

Homes in Cass County, Minnesota, 2019 to 2023
HomesCass CountyMinnesota
Housing units24,2942,519,538
Detached houses85%66%
In buildings of 5 or more3%19%
Mobile homes9%3%
Built before 196014%29%
Built since 200031%22%
Middle year built19901978
Owner-occupied85%72%

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