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Radon Levels in Mille Lacs County, Minnesota

EPA puts Mille Lacs County in Zone 2, its middle radon zone, and only 21 radon tests from it are on file with CDC (2023). 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

    27.7%

    15.7 pts below MN

    Mille Lacs
    27.7%
    Minnesota
    43.4%

    282 tests, 2008 to 2017

  • Median result

    2.5pCi/L

    Below action level

    Mille Lacs
    2.5 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    282

    59th of 85 by tests

    Mille Lacs
    282
    Hennepin
    35,213

    Reported to CDC before any fix, 2008 to 2017

  • 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

    79 of 85

    Lowest quarter

    Mille Lacs
    27.7%
    Rock
    83.8%

    By share, of 85 with 30+ tests

Read a result for Mille Lacs County

Starts at Mille Lacs County's median, 2.5 pCi/L

2.5pCi/L

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

EPA’s reading of 2.5 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. Mille Lacs County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Mille Lacs County, At a glance

Mille Lacs County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Mille Lacs 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 95% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Mille Lacs County, 2023

Share of reported tests at or above 4 pCi/L, by year, Mille Lacs County
Share of reported tests at or above 4 pCi/L, by year, Mille Lacs County
YearShare of reported tests at or above 4 pCi/L
201434.3%
201532.5%
201627.1%
201733.3%
201835.0%
201916.5%
202024.5%
202125.0%
202227.3%
202333.3%

2023: 33.3%. Across these years the share ran from 16.5% to 35.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 21 tests were reported to CDC for Mille Lacs County over 2023, 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: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).

How to read these figures

Mille Lacs County, Compared

Mille Lacs County radon figures, compared

Calculated by Radon411

Mille Lacs County's 282 reported tests over the 2008 to 2017 laboratory totals had a middle value of 2.5 pCi/L and a maximum of 35.9 pCi/L, and 27.7% reached 4 pCi/L. Minnesota as a whole (87 Minnesota counties, pooled) comes to 43.4%: 15.7 points higher than here.

The newest figure, in 2023, counts only 21 tests (33.3% at or above 4 pCi/L), too few to compare, so this reading uses the 282-test figure.

Among its state's counties it ranks 79th of 85 Minnesota counties with 30 or more tests for the same period. Statewide for the same period, Rock County reported the highest share (83.8%) and Anoka County the lowest (17.4%).

Below the action level, 115 tests (40.8%) came in under 2 pCi/L, against 27.4% statewide, and 89 tests (31.6%) fell between 2 and 4, against 29.2% statewide. The busiest year on file was 2019, with 85 tests reported; the quietest, 2023, had 21.

EPA's 1993 zone map puts Mille Lacs County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 95% of the county's land moderate radon potential.

Next door, the shares run from 18.6% in Isanti County to 46.5% in Kanabec County, with Isanti County below Mille Lacs County. Over 9 years of annual figures the share fell 7.0 points, from 34.3% in 2014 to 27.3% in 2022; its peak was 35.0% in 2018.

CDC also counts 11 tests taken after mitigation in Mille Lacs County for the same period: tests in homes where a fix was already in.

Share of reported tests at or above 4 pCi/L by year, Mille Lacs County against Minnesota2014 to 2022, years with 30 or more tests: Mille Lacs County 34.3% to 27.3%, the state's pooled share 31.6% in 2022.
Mille Lacs CountyMinnesota, pooled
Share of reported tests at or above 4 pCi/L by year, Mille Lacs County against Minnesota: data table
YearTestsMille Lacs County, at or above 4 pCi/LMinnesota, pooled
20147034.3%42.9%
20154032.5%43.6%
20164827.1%37.0%
20173933.3%38.2%
20184035.0%38.3%
20198516.5%36.1%
20204924.5%31.8%
20215225.0%33.1%
20224427.3%31.6%
Mille Lacs County against Minnesota, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Mille Lacs County
Mille Lacs County28227.7%2.5 pCi/LThis county
Minnesota, pooled87 counties, pooled130,91243.4%Not pooled+15.7 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+8.0 points
Rock Countyhighest in the state21083.8%7.7 pCi/L+56.1 points
Anoka Countylowest in the state5,95817.4%1.9 pCi/L−10.3 points
Kanabec County, MNborders it33346.5%3.6 pCi/L+18.8 points
Sherburne County, MNborders it2,09637.7%3.1 pCi/L+10.0 points
Morrison County, MNborders it83136.3%3.0 pCi/L+8.6 points
Benton County, MNborders it48530.7%2.8 pCi/L+3.0 points
Aitkin County, MNborders it22630.5%2.5 pCi/L+2.8 points
Crow Wing County, MNborders it1,16327.9%2.4 pCi/L+0.2 points
Isanti County, MNborders it44718.6%2.3 pCi/L−9.1 points
Where Mille Lacs County's reported results fell, 2008 to 2017, laboratory, beside Minnesota and the United States
ResultMille Lacs County testsMille Lacs County shareMinnesota shareU.S. shareAgainst Minnesota
Under 2 pCi/L11540.8%27.4%39.6%+13.4 points
2 to 4 pCi/L8931.6%29.2%24.7%+2.4 points
4 pCi/L and above7827.7%43.4%35.7%−15.7 points
Mille Lacs County ranked among the 85 Minnesota counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Benton County74 of 8548530.7%2.8 pCi/L
Aitkin County75 of 8522630.5%2.5 pCi/L
Ramsey County76 of 859,61230.5%2.7 pCi/L
Roseau County77 of 854829.2%3.0 pCi/L
Crow Wing County78 of 851,16327.9%2.4 pCi/L
Mille Lacs County79 of 8528227.7%2.5 pCi/L
Koochiching County80 of 8514424.3%1.6 pCi/L
Pine County81 of 8523124.2%2.3 pCi/L
St. Louis County82 of 854,60823.7%2.0 pCi/L
Lake County83 of 8520221.8%1.6 pCi/L
Isanti County84 of 8544718.6%2.3 pCi/L
Mille Lacs County radon tests by year, against Minnesota's pooled share
YearTestsAt or above 4 pCi/LMedianHighestMinnesota, pooledChange from the row before
20232133.3%2.6 pCi/L44.8 pCi/L34.6%+6.0 points
20224427.3%1.8 pCi/L14.2 pCi/L31.6%+2.3 points
20215225.0%2.5 pCi/L13.1 pCi/L33.1%+0.5 points
20204924.5%2.5 pCi/L9.3 pCi/L31.8%+8.0 points
20198516.5%1.5 pCi/L11.1 pCi/L36.1%−18.5 points
20184035.0%2.8 pCi/L10.9 pCi/L38.3%+1.7 points
20173933.3%3.2 pCi/L11.7 pCi/L38.2%+6.2 points
20164827.1%2.5 pCi/L19.4 pCi/L37.0%−5.4 points
20154032.5%2.5 pCi/L11.6 pCi/L43.6%−1.8 points
20147034.3%2.8 pCi/L15.1 pCi/L42.9%First on file

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

Mille Lacs County, State data

Minnesota's own radon test data

Measured

What Minnesota's own agencies publish about radon tests in Mille Lacs 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 Mille Lacs 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

27.7%

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

Median result

2.3 pCi/L

Average result

3.1 pCi/L

Tests behind these figures

48 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.

Mille Lacs County, Geology

The ground under Mille Lacs County

Predicted

Most of the ground under Mille Lacs County is one class on USGS's geologic map: 95.2% of its land is moderate radon potential, with 4.8% high. 95.2% of it lies in the area the map calls Superior Upland/Central Lowland-Western Lake Section, to which USGS gives a radon index of 10, in the moderate band (9 to 11).

USGS's geologic areas under Mille Lacs County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Superior Upland/Central Lowland-Western Lake SectionGlacial deposits derived primarily from volcanic rock.Moderate1095.2%
Central Lowland-Till PrairieSilty and clayey till derived from shale and sandstone.High144.8%

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

Mille Lacs County beside the ground around it

Minnesota as a whole has more high-potential ground than Mille Lacs County: 61.1% of its land, against 4.8% here. Of the 7 counties that border it, 3 have more high-potential ground, Sherburne County the most at 98.5%.

Share of land by USGS radon potential: Mille Lacs County, the 7 counties bordering it and Minnesota
AreaEPA zoneLow potentialModerate potentialHigh potential
Mille Lacs CountyZone 2None95.2%4.8%
Kanabec CountyZone 1None98.7%1.3%
Benton CountyZone 2None91.6%8.4%
Isanti CountyZone 2None2.3%97.7%
Morrison CountyZone 2None97.7%2.3%
Sherburne CountyZone 1None1.5%98.5%
Crow Wing CountyZone 2None99.0%1.0%
Aitkin CountyZone 2None100%None
Minnesota87 counties, pooled by land areaVariesNone38.9%61.1%

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

Local help

Mille Lacs County, Local resources

Radon testing and mitigation in Mille Lacs 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

Mille Lacs County, Questions

Questions about radon in Mille Lacs County

Are radon levels high in Mille Lacs County?

In 2023, 33.3% of the radon tests reported to CDC for Mille Lacs County, Minnesota were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.6 pCi/L. Of 85 Minnesota counties with 30 or more tests for the same period, 78 reported a higher share; pooled, the state comes to 43.4%.

Which counties border Mille Lacs County?

Mille Lacs County borders 7 counties: Kanabec County, Benton County, Isanti County, Morrison County, Sherburne County, Crow Wing County and Aitkin County.

Products

Mille Lacs County, Products

Testing a home in Mille Lacs County

In Mille Lacs County, 27.7% of 282 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 43.4% pooled across Minnesota. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Mille Lacs County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Mille Lacs County homes, compared

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Mille Lacs County, Bordering counties

Counties bordering Mille Lacs County

Calculated by Radon411

Mille Lacs County, Cities and towns

Cities and towns in Mille Lacs County

The Census Bureau estimates 27,753 residents in Mille Lacs County for July 1, 2025, 1,278 more than in 2020 (+4.8%). That works out to 48 people per square mile of land. Princeton, the largest place on its list (5,480 residents in all), extends beyond Mille Lacs County, so no share of the total is worked out for it. Reported testing is thin here: 282 tests over 2008 to 2017, or 10.2 for every 1,000 residents (2025 estimate), where Minnesota as a whole comes to 22.5.

From Princeton to Bock, CDC publishes no figure by town: each reads Mille Lacs County's.

The cities and towns in Mille Lacs County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Princetonextends beyond Mille Lacs County5,480+9.2%Counted whole
Milaca3,041+1.0%11.0%
Onamia839+7.3%3.0%
Isle830+2.0%3.0%
Foreston581+4.3%2.1%
Wahkon251+5.5%0.9%
Pease249+3.3%0.9%
Bock82+5.1%0.3%

8 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 Mille Lacs County is counted whole, so it has no share.

Mille Lacs County, Homes

Homes in Mille Lacs County

Of Mille Lacs County's 12,958 homes, 73% are detached houses, against 66% across Minnesota; 10% are mobile homes. Half of its homes were built before 1982, close to Minnesota's 1978: 25% date from before 1960 and 28% from 2000 or later. Owners live in 78% of the occupied homes (Minnesota: 72%), so for most households a test and a fix are their own to order.

Homes in Mille Lacs County, Minnesota, 2019 to 2023
HomesMille Lacs CountyMinnesota
Housing units12,9582,519,538
Detached houses73%66%
In buildings of 5 or more10%19%
Mobile homes10%3%
Built before 196025%29%
Built since 200028%22%
Middle year built19821978
Owner-occupied78%72%

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