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Radon Levels in Forest County, Wisconsin

EPA puts Forest County in Zone 2, its middle radon zone, and high results are common there: 40.0% of the 45 radon tests reported to CDC (2023) 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    40.0%

    4.3 pts above WI

    Forest
    40.0%
    Wisconsin
    35.7%

    45 tests, 2023

  • Median result

    2.9pCi/L

    Below action level

    Forest
    2.9 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    45

    64th of 69 by tests

    Forest
    45
    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

    32 of 69

    Middle half

    Forest
    40.0%
    Langlade
    65.8%

    By share, of 69 with 30+ tests

Read a result for Forest County

Starts at Forest County's median, 2.9 pCi/L

2.9pCi/L

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

EPA’s reading of 2.9 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. Forest County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Forest County, At a glance

Forest County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Forest 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 97% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Forest County, 2023

Share of reported tests at or above 4 pCi/L, by year, Forest County
Share of reported tests at or above 4 pCi/L, by year, Forest County
YearShare of reported tests at or above 4 pCi/L
201442.9%
201559.1%
201634.4%
201763.0%
201959.4%
202058.1%
202176.5%
202260.0%
202340.0%

2023: 40.0%. Across these years the share ran from 34.4% to 76.5%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 45 tests reported to CDC for Forest 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

Forest County, Compared

Forest County radon figures, compared

Calculated by Radon411

In Forest County, about 4 in 10 reported tests in 2023 (18 of 45) were at or above EPA's action level. Against the national pool of 33.4%, the gap is 6.6 points higher. Across 72 Wisconsin counties pooled together, 35.7% of tests reached that level, so Forest County runs 4.3 points above its state.

Of 5 neighbours with a figure, 4 reported a larger share at or above 4 pCi/L and 1 a smaller one; the spread is 21.7% (Vilas County) to 65.8% (Langlade County). By share, Forest County is 32nd of 69 Wisconsin counties with 30 or more tests for the same period.

Year by year, 2016 opened at 34.4% and 2023 closed at 40.0% (up 5.6 points), with 2019 the high at 59.4%. Half the tests came in under 2.9 pCi/L and half over it; the single highest reached 28.7 pCi/L. Below the action level, 14 tests (31.1%) came in under 2 pCi/L, against 41.4% statewide, and 13 tests (28.9%) 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 40.0% share point the same way here. USGS geology rates 97% of the county's land moderate radon potential.

The busiest year on file was 2016, with 93 tests reported; the quietest, 2014, had 14.

Share of reported tests at or above 4 pCi/L by year, Forest County against Wisconsin2016 to 2023, years with 30 or more tests: Forest County 34.4% to 40.0%, the state's pooled share 35.7% in 2023.
Forest CountyWisconsin, pooled
Share of reported tests at or above 4 pCi/L by year, Forest County against Wisconsin: data table
YearTestsForest County, at or above 4 pCi/LWisconsin, pooled
20169334.4%45.2%
20193259.4%42.9%
20203158.1%27.0%
20234540.0%35.7%
Forest County against Wisconsin, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Forest County
Forest County4540.0%2.9 pCi/LThis county
Wisconsin, pooled72 counties, pooled20,87935.7%Not pooled−4.3 points
United States, pooled642 counties, pooled128,74033.4%Not pooled−6.6 points
Iowa Countyhighest in the state14661.0%4.8 pCi/L+21.0 points
Bayfield Countylowest in the state355.7%1.5 pCi/L−34.3 points
Langlade County, WIborders it22565.8%6.0 pCi/L+25.8 points
Oconto County, WIborders it13052.3%4.5 pCi/L+12.3 points
Marinette County, WIborders it6144.3%2.6 pCi/L+4.3 points
Florence County, WIborders it1643.8%3.7 pCi/L+3.8 points
Oneida County, WIborders it13540.7%2.7 pCi/L+0.7 points
Vilas County, WIborders it10621.7%2.1 pCi/L−18.3 points
Where Forest County's reported results fell, 2023, beside Wisconsin and the United States
ResultForest County testsForest County shareWisconsin shareU.S. shareAgainst Wisconsin
Under 2 pCi/L1431.1%41.4%41.4%−10.3 points
2 to 4 pCi/L1328.9%23.0%25.2%+5.9 points
4 pCi/L and above1840.0%35.7%33.4%+4.3 points
Forest 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
Trempealeau County27 of 6911242.0%3.3 pCi/L
Sauk County28 of 6924141.1%3.3 pCi/L
Oneida County29 of 6913540.7%2.7 pCi/L
Outagamie County30 of 6933740.7%3.1 pCi/L
Green Lake County31 of 697940.5%3.4 pCi/L
Forest County32 of 694540.0%2.9 pCi/L
Jackson County33 of 699338.7%3.2 pCi/L
Rusk County34 of 695738.6%3.2 pCi/L
Walworth County35 of 6934037.9%2.8 pCi/L
Dunn County36 of 6917137.4%2.9 pCi/L
St. Croix County37 of 6934837.4%3.0 pCi/L
Forest County radon tests by year, against Wisconsin's pooled share
YearTestsAt or above 4 pCi/LMedianHighestWisconsin, pooledChange from the row before
20234540.0%2.9 pCi/L28.7 pCi/L35.7%−20.0 points
20221560.0%4.4 pCi/L23.3 pCi/L42.9%−16.5 points
20211776.5%6.1 pCi/L32.4 pCi/L39.9%+18.4 points
20203158.1%4.5 pCi/L13.5 pCi/L27.0%−1.3 points
20193259.4%7.5 pCi/L36.9 pCi/L42.9%−3.6 points
20172763.0%4.6 pCi/L47.5 pCi/L44.8%+28.6 points
20169334.4%1.8 pCi/L33.1 pCi/L45.2%−24.7 points
20152259.1%6.3 pCi/L22.8 pCi/L51.6%+16.2 points
20141442.9%3.3 pCi/L10.0 pCi/L51.1%First on file

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

Forest County, Geology

The ground under Forest County

Predicted

Most of the ground under Forest County is one class on USGS's geologic map: 97.3% of its land is moderate radon potential, with 2.7% high. 97.3% of it lies in the area the map calls Chippewa, Wisconsin Valley, and Langlade sublobes of the Superior Lobe, to which USGS gives a radon index of 10, in the moderate band (9 to 11).

USGS's geologic areas under Forest County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Chippewa, Wisconsin Valley, and Langlade sublobes of the Superior LobeGranite, granite-derived glacial deposits, and mafic volcanic rocks.Moderate1097.3%
Wolf River BatholithPlutonic granitic rocks including quartz monzonite, syenite, monzonite, anorthosite.High132.7%

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

Forest County beside the ground around it

Wisconsin as a whole has more high-potential ground than Forest County: 34.8% of its land, against 2.7% here. Of the 7 counties that border it, 3 have more high-potential ground, Langlade County the most at 55.1%.

Share of land by USGS radon potential: Forest County, the 7 counties bordering it and Wisconsin
AreaEPA zoneLow potentialModerate potentialHigh potential
Forest CountyZone 2None97.3%2.7%
Florence CountyZone 2None100%None
Iron County, MIZone 2None100%None
Oneida CountyZone 2None100%None
Vilas CountyZone 2None100%None
Langlade CountyZone 1None44.9%55.1%
Marinette CountyZone 2None95.8%4.1%
Oconto CountyZone 2None67.2%32.6%
Wisconsin72 counties, pooled by land areaVaries1.4%63.5%34.8%

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

Local help

Forest County, Local resources

Radon testing and mitigation in Forest 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

Forest County, Questions

Questions about radon in Forest County

Are radon levels high in Forest County?

In 2023, 40.0% of the radon tests reported to CDC for Forest County, Wisconsin were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.9 pCi/L. Of 69 Wisconsin counties with 30 or more tests for the same period, 31 reported a higher share; pooled, the state comes to 35.7%.

Which counties border Forest County?

Forest County borders 7 counties: Florence County, WI, Iron County, MI, Oneida County, WI, Vilas County, WI, Langlade County, WI, Marinette County, WI and Oconto County, WI.

Products

Forest County, Products

Testing a home in Forest County

In Forest County, 40.0% of 45 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 Forest County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Forest County homes, compared

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Forest County, Bordering counties

Counties bordering Forest County

Calculated by Radon411

Forest County, Cities and towns

Cities and towns in Forest County

The Census Bureau estimates 9,574 residents in Forest County for July 1, 2025, 401 more than in 2020 (+4.4%). Spread over its land, that is 9.4 people to the square mile. Crandon, its one incorporated place, has 1,726 residents, 18.0% of the total. CDC's 45 reported tests for 2023 work out to 4.7 per 1,000 residents (2025 estimate), close to Wisconsin's 3.5.

Crandon is the one incorporated place here; CDC publishes no figure by town, so it reads Forest County's.

Crandon, Forest County: residents on July 1, 2025
PlaceResidentsSince 2020Share of residents
Crandon1,726+0.8%18.0%

One incorporated place, 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).

Forest County, Homes

Homes in Forest County

Forest County is a place of houses on their own lots: 86% of its 8,696 homes are detached single-family houses, against 66% across Wisconsin. Half of its homes were built before 1980, close to Wisconsin's 1975: 25% date from before 1960 and 20% from 2000 or later. Owners live in 82% of the occupied homes (Wisconsin: 68%), so for most households a test and a fix are their own to order.

Homes in Forest County, Wisconsin, 2019 to 2023
HomesForest CountyWisconsin
Housing units8,6962,750,750
Detached houses86%66%
In buildings of 5 or more3%17%
Mobile homes10%3%
Built before 196025%34%
Built since 200020%20%
Middle year built19801975
Owner-occupied82%68%

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