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Radon Levels in Polk County, Wisconsin

EPA puts Polk County in Zone 2, its middle radon zone, and 33.6% of its 122 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

    33.6%

    2.1 pts below WI

    Polk
    33.6%
    Wisconsin
    35.7%

    122 tests, 2023

  • Median result

    2.8pCi/L

    Below action level

    Polk
    2.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    122

    42nd of 69 by tests

    Polk
    122
    Dane
    2,887

    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 Wisconsin

    45 of 69

    Middle half

    Polk
    33.6%
    Langlade
    65.8%

    By share, of 69 with 30+ tests

Read a result for Polk County

Starts at Polk County's median, 2.8 pCi/L

2.8pCi/L

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

EPA’s reading of 2.8 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. Polk County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Polk County, At a glance

Polk County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Polk 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 87% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Polk County, 2023

Share of reported tests at or above 4 pCi/L, by year, Polk County
Share of reported tests at or above 4 pCi/L, by year, Polk County
YearShare of reported tests at or above 4 pCi/L
201440.1%
201542.1%
201635.8%
201741.7%
201941.0%
202041.8%
202131.0%
202247.8%
202333.6%

2023: 33.6%. Across these years the share ran from 31.0% to 47.8%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 122 tests reported to CDC for Polk 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

Polk County, Compared

Polk County radon figures, compared

Calculated by Radon411

In Polk County, about 3 in 10 reported tests in 2023 (41 of 122) were at or above EPA's action level. Against the national pool of 33.4%, the gap is 0.2 points higher. Across 72 Wisconsin counties pooled together, 35.7% of tests reached that level, so Polk County runs 2.1 points below its state.

Of 6 neighbours with a figure, 4 reported a larger share at or above 4 pCi/L and 2 a smaller one; the spread is 21.3% (Washington County, MN) to 37.4% (St. Croix County). By share, Polk County is 45th of 69 Wisconsin counties with 30 or more tests for the same period.

Year by year, 2014 opened at 40.1% and 2023 closed at 33.6% (down 6.5 points), with 2022 the high at 47.8%. Half the tests came in under 2.8 pCi/L and half over it; the single highest reached 19.5 pCi/L. Below the action level, 40 tests (32.8%) came in under 2 pCi/L, against 41.4% statewide, and 41 tests (33.6%) fell between 2 and 4, against 23.0% statewide.

Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 33.6% share point the same way here. USGS geology rates 87% of the county's land moderate radon potential.

The busiest year on file was 2015, with 202 tests reported; the quietest, 2020, had 79.

Share of reported tests at or above 4 pCi/L by year, Polk County against Wisconsin2014 to 2023, years with 30 or more tests: Polk County 40.1% to 33.6%, the state's pooled share 35.7% in 2023.
Polk CountyWisconsin, pooled
Share of reported tests at or above 4 pCi/L by year, Polk County against Wisconsin: data table
YearTestsPolk County, at or above 4 pCi/LWisconsin, pooled
201419740.1%51.1%
201520242.1%51.6%
201616235.8%45.2%
201712741.7%44.8%
201911741.0%42.9%
20207941.8%27.0%
202111631.0%39.9%
20229247.8%42.9%
202312233.6%35.7%
Polk County against Wisconsin, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Polk County
Polk County12233.6%2.8 pCi/LThis county
Wisconsin, pooled72 counties, pooled20,87935.7%Not pooled+2.1 points
United States, pooled642 counties, pooled128,74033.4%Not pooled−0.2 points
Langlade Countyhighest in the state22565.8%6.0 pCi/L+32.2 points
Bayfield Countylowest in the state355.7%1.5 pCi/L−27.9 points
St. Croix County, WIborders it34837.4%3.0 pCi/L+3.8 points
Dunn County, WIborders it17137.4%2.9 pCi/L+3.8 points
Chisago County, MNborders it16634.9%2.9 pCi/L+1.3 points
Barron County, WIborders it19934.7%2.5 pCi/L+1.1 points
Burnett County, WIborders it5223.1%1.6 pCi/L−10.5 points
Washington County, MNborders it1,51821.3%1.9 pCi/L−12.3 points
Where Polk County's reported results fell, 2023, beside Wisconsin and the United States
ResultPolk County testsPolk County shareWisconsin shareU.S. shareAgainst Wisconsin
Under 2 pCi/L4032.8%41.4%41.4%−8.6 points
2 to 4 pCi/L4133.6%23.0%25.2%+10.6 points
4 pCi/L and above4133.6%35.7%33.4%−2.1 points
Polk County ranked among the 69 Wisconsin counties with 30 or more tests, by share at or above 4 pCi/L, 2023
CountyRankTestsAt or above 4 pCi/LMedian
Chippewa County40 of 6931135.7%2.5 pCi/L
Portage County41 of 6933435.6%3.0 pCi/L
Dane County42 of 692,88734.9%2.5 pCi/L
Barron County43 of 6919934.7%2.5 pCi/L
Green County44 of 6923533.6%2.1 pCi/L
Polk County45 of 6912233.6%2.8 pCi/L
Richland County46 of 694833.3%2.9 pCi/L
Eau Claire County47 of 6947432.7%2.8 pCi/L
La Crosse County48 of 6977131.4%2.7 pCi/L
Manitowoc County49 of 6920931.1%2.2 pCi/L
Pierce County50 of 6913630.9%2.7 pCi/L
Polk County radon tests by year, against Wisconsin's pooled share
YearTestsAt or above 4 pCi/LMedianHighestWisconsin, pooledChange from the row before
202312233.6%2.8 pCi/L19.5 pCi/L35.7%−14.2 points
20229247.8%3.8 pCi/L41.2 pCi/L42.9%+16.8 points
202111631.0%2.7 pCi/L17.2 pCi/L39.9%−10.8 points
20207941.8%3.1 pCi/L29.6 pCi/L27.0%+0.8 points
201911741.0%3.2 pCi/L43.5 pCi/L42.9%−0.7 points
201712741.7%3.3 pCi/L21.1 pCi/L44.8%+5.9 points
201616235.8%2.7 pCi/L17.8 pCi/L45.2%−6.3 points
201520242.1%3.4 pCi/L33.7 pCi/L51.6%+2.0 points
201419740.1%3.3 pCi/L29.3 pCi/L51.1%First on file

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

Polk County, Geology

The ground under Polk County

Predicted

Most of the ground under Polk County is one class on USGS's geologic map: 86.6% of its land is moderate radon potential, with 13.4% high. The map puts 82.6% of Polk County in the area it calls Superior Lobe and 13.1% in Western Highlands, with one smaller area beside them. USGS gives the first a radon index of 10, in the moderate band (9 to 11), and the second 12, in the high band (12 to 17).

USGS's geologic areas under Polk County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Superior LobeGlacial deposits derived from sandstone and volcanic rocks.Moderate1082.6%
Western HighlandsGlacial deposits derived largely from Ordovician carbonate rocks.High1213.1%
Central Plain/Northern HighlandPre-Late Wisconsinan glacial deposits derived from sandstone and carbonate rocks.Moderate104.0%

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

Polk County beside the ground around it

Wisconsin as a whole has more high-potential ground than Polk County: 34.8% of its land, against 13.4% here. Of the 6 counties that border it, 3 have more high-potential ground, Washington County, MN the most at 100%.

Share of land by USGS radon potential: Polk County, the 6 counties bordering it and Wisconsin
AreaEPA zoneLow potentialModerate potentialHigh potential
Polk CountyZone 2None86.6%13.4%
Chisago County, MNZone 2NoneNone100%
Barron CountyZone 2None100%None
St. Croix CountyZone 1None0.3%99.7%
Burnett CountyZone 2None99.7%0.3%
Washington County, MNZone 1NoneNone100%
Dunn CountyZone 2None90.3%9.7%
Wisconsin72 counties, pooled by land areaVaries1.4%63.5%34.8%

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

Local help

Polk County, Local resources

Radon testing and mitigation in Polk County

What Wisconsin's program says
Phone
1-888-569-7236
Email
DHSRadon@dhs.wisconsin.gov
Licensing of radon professionals
The State of Wisconsin does not require contractors performing radon measurement or mitigation work to be state licensed or nationally certified.

What it means

Polk County, Questions

Questions about radon in Polk County

Are radon levels high in Polk County?

In 2023, 33.6% of the radon tests reported to CDC for Polk County, Wisconsin were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.8 pCi/L. Of 69 Wisconsin counties with 30 or more tests for the same period, 44 reported a higher share; pooled, the state comes to 35.7%.

Which counties border Polk County?

Polk County borders 6 counties: Chisago County, MN, Barron County, WI, St. Croix County, WI, Burnett County, WI, Washington County, MN and Dunn County, WI.

Products

Polk County, Products

Testing a home in Polk County

In Polk County, 33.6% of 122 tests reported to CDC in 2023 reached 4 pCi/L, against 35.7% pooled across Wisconsin. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Polk County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Polk County homes, compared

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Polk County, Bordering counties

Counties bordering Polk County

Calculated by Radon411

Polk County, Cities and towns

Cities and towns in Polk County

The Census Bureau estimates 45,803 residents in Polk County for July 1, 2025, 775 more than in 2020 (+1.7%). That works out to 50 people per square mile of land. No town dominates: Amery, the largest, has 2,927 residents, 6.4% of the total. CDC's 122 reported tests for 2023 work out to 2.7 per 1,000 residents (2025 estimate), close to Wisconsin's 3.5.

From Amery to Clayton, CDC publishes no figure by town: each reads Polk County's.

The cities and towns in Polk County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Amery2,927−1.2%6.4%
Osceola2,890+4.1%6.3%
St. Croix Falls2,370+7.2%5.2%
Frederic1,133−2.1%2.5%
Clear Lake1,100+0.4%2.4%
Luck1,063−2.7%2.3%
Turtle Lakeextends beyond Polk County1,023−1.7%Counted whole
Balsam Lake945+0.5%2.1%
Milltown932−1.6%2.0%
Dresser930−1.2%2.0%
Centuria877−1.5%1.9%
Clayton546−0.9%1.2%

12 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 Polk County is counted whole, so it has no share.

Polk County, Homes

Homes in Polk County

Polk County is a place of houses on their own lots: 82% of its 24,377 homes are detached single-family houses, against 66% across Wisconsin. Half of its homes were built before 1980, close to Wisconsin's 1975: 27% date from before 1960 and 24% from 2000 or later. Owners live in 81% of the occupied homes (Wisconsin: 68%), so for most households a test and a fix are their own to order.

Homes in Polk County, Wisconsin, 2019 to 2023
HomesPolk CountyWisconsin
Housing units24,3772,750,750
Detached houses82%66%
In buildings of 5 or more5%17%
Mobile homes7%3%
Built before 196027%34%
Built since 200024%20%
Middle year built19801975
Owner-occupied81%68%

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