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Radon Levels in Ashland County, Wisconsin

EPA puts Ashland County in Zone 2, its middle radon zone, and 29.3% of its 41 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

    29.3%

    6.4 pts below WI

    Ashland
    29.3%
    Wisconsin
    35.7%

    41 tests, 2023

  • Median result

    2.3pCi/L

    Below action level

    Ashland
    2.3 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    41

    66th of 69 by tests

    Ashland
    41
    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

    51 of 69

    Middle half

    Ashland
    29.3%
    Langlade
    65.8%

    By share, of 69 with 30+ tests

Read a result for Ashland County

Starts at Ashland 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. Ashland County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Ashland County, At a glance

Ashland County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Ashland 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 92% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Ashland County, 2023

Share of reported tests at or above 4 pCi/L, by year, Ashland County
Share of reported tests at or above 4 pCi/L, by year, Ashland County
YearShare of reported tests at or above 4 pCi/L
201423.6%
201515.1%
201614.3%
201711.5%
201922.6%
20205.7%
20218.0%
202238.5%
202329.3%

2023: 29.3%. Across these years the share ran from 5.7% to 38.5%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 41 tests reported to CDC for Ashland 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

Ashland County, Compared

Ashland County radon figures, compared

Calculated by Radon411

Ashland County's 41 reported tests in 2023 had a middle value of 2.3 pCi/L and a maximum of 13.7 pCi/L, and 29.3% reached 4 pCi/L. Wisconsin as a whole (72 Wisconsin counties, pooled) comes to 35.7%: 6.4 points higher than here.

Among its state's counties it ranks 51st of 69 Wisconsin counties with 30 or more tests for the same period. Statewide for the same period, Langlade County reported the highest share (65.8%) and Bayfield County the lowest (5.7%).

Below the action level, 17 tests (41.5%) came in under 2 pCi/L, against 41.4% statewide, and 12 tests (29.3%) fell between 2 and 4, against 23.0% statewide. The busiest year on file was 2015, with 152 tests reported; the quietest, 2022, had 13.

EPA's 1993 zone map puts Ashland County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 92% of the county's land moderate radon potential.

Next door, the shares run from 5.7% in Bayfield County to 42.6% in Sawyer County, with Bayfield County below Ashland County. Over 7 years of annual figures the share rose 5.7 points, from 23.6% in 2014 to 29.3% in 2023; its peak was 29.3% in 2023.

Share of reported tests at or above 4 pCi/L by year, Ashland County against Wisconsin2014 to 2023, years with 30 or more tests: Ashland County 23.6% to 29.3%, the state's pooled share 35.7% in 2023.
Ashland CountyWisconsin, pooled
Share of reported tests at or above 4 pCi/L by year, Ashland County against Wisconsin: data table
YearTestsAshland County, at or above 4 pCi/LWisconsin, pooled
20145523.6%51.1%
201515215.1%51.6%
20163514.3%45.2%
20193122.6%42.9%
2020355.7%27.0%
2021508.0%39.9%
20234129.3%35.7%
Ashland County against Wisconsin, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Ashland County
Ashland County4129.3%2.3 pCi/LThis county
Wisconsin, pooled72 counties, pooled20,87935.7%Not pooled+6.4 points
United States, pooled642 counties, pooled128,74033.4%Not pooled+4.1 points
Langlade Countyhighest in the state22565.8%6.0 pCi/L+36.5 points
Douglas Countylowest in the state449.1%1.5 pCi/L−20.2 points
Sawyer County, WIborders it4742.6%3.2 pCi/L+13.3 points
Price County, WIborders it6036.7%2.8 pCi/L+7.4 points
Iron County, WIborders it922.2%2.1 pCi/L−7.1 points
Bayfield County, WIborders it355.7%1.5 pCi/L−23.6 points
Where Ashland County's reported results fell, 2023, beside Wisconsin and the United States
ResultAshland County testsAshland County shareWisconsin shareU.S. shareAgainst Wisconsin
Under 2 pCi/L1741.5%41.4%41.4%+0.1 points
2 to 4 pCi/L1229.3%23.0%25.2%+6.3 points
4 pCi/L and above1229.3%35.7%33.4%−6.4 points
Ashland 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
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
Ashland County51 of 694129.3%2.3 pCi/L
Columbia County52 of 6916328.8%2.0 pCi/L
Waushara County53 of 697125.4%1.9 pCi/L
Clark County54 of 697525.3%2.2 pCi/L
Lincoln County55 of 698123.5%2.1 pCi/L
Burnett County56 of 695223.1%1.6 pCi/L
Ashland County radon tests by year, against Wisconsin's pooled share
YearTestsAt or above 4 pCi/LMedianHighestWisconsin, pooledChange from the row before
20234129.3%2.3 pCi/L13.7 pCi/L35.7%−9.2 points
20221338.5%3.6 pCi/L18.5 pCi/L42.9%+30.5 points
2021508.0%0.9 pCi/L6.5 pCi/L39.9%+2.3 points
2020355.7%1.0 pCi/L4.2 pCi/L27.0%−16.9 points
20193122.6%1.8 pCi/L9.3 pCi/L42.9%+11.1 points
20172611.5%2.0 pCi/L6.8 pCi/L44.8%−2.8 points
20163514.3%1.6 pCi/L9.0 pCi/L45.2%−0.8 points
201515215.1%1.8 pCi/L15.1 pCi/L51.6%−8.5 points
20145523.6%1.8 pCi/L13.5 pCi/L51.1%First on file

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

Ashland County, Geology

The ground under Ashland County

Predicted

USGS's geologic map puts all of Ashland County's mapped land in one class: moderate radon potential. The map puts 58.9% of Ashland County in the area it calls Chippewa, Wisconsin Valley, and Langlade sublobes of the Superior Lobe and 33.1% in Superior Lobe. USGS gives both a radon index of 10, in the moderate band (9 to 11).

USGS's geologic areas under Ashland 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.Moderate1058.9%
Superior LobeGlacial deposits derived from sandstone and volcanic rocks.Moderate1033.1%

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

Ashland County beside the ground around it

Across Wisconsin 34.8% of the land is rated high; none of Ashland County's is. Every one of the 4 counties that border it has more moderate-potential ground, Price County the most at 100%.

Share of land by USGS radon potential: Ashland County, the 4 counties bordering it and Wisconsin
AreaEPA zoneLow potentialModerate potentialHigh potential
Ashland CountyZone 2None91.9%None
Bayfield CountyZone 2None98.9%None
Iron CountyZone 2None99.8%None
Sawyer CountyZone 2None100%None
Price CountyZone 2None100%None
Wisconsin72 counties, pooled by land areaVaries1.4%63.5%34.8%

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

Local help

Ashland County, Local resources

Radon testing and mitigation in Ashland 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

Ashland County, Questions

Questions about radon in Ashland County

Are radon levels high in Ashland County?

In 2023, 29.3% of the radon tests reported to CDC for Ashland County, Wisconsin were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.3 pCi/L. Of 69 Wisconsin counties with 30 or more tests for the same period, 50 reported a higher share; pooled, the state comes to 35.7%.

Which counties border Ashland County?

Ashland County borders 4 counties: Bayfield County, Iron County, Sawyer County and Price County.

Products

Ashland County, Products

Testing a home in Ashland County

In Ashland County, 29.3% of 41 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 Ashland County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Ashland County homes, compared

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Ashland County, Bordering counties

Counties bordering Ashland County

Calculated by Radon411

Ashland County, Cities and towns

Cities and towns in Ashland County

The Census Bureau estimates 16,203 residents in Ashland County for July 1, 2025, 175 more than in 2020 (+1.1%). That works out to 16 people per square mile of land. Ashland, the largest place on its list (7,927 residents in all), extends beyond Ashland County, so no share of the total is worked out for it. CDC's 41 reported tests for 2023 work out to 2.5 per 1,000 residents (2025 estimate), close to Wisconsin's 3.5.

From Ashland to Butternut, CDC publishes no figure by town: each reads Ashland County's.

The cities and towns in Ashland County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Ashlandextends beyond Ashland County7,927+0.2%Counted whole
Mellen683−2.0%4.2%
Butternut364−0.3%2.2%

3 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 Ashland County is counted whole, so it has no share.

Ashland County, Homes

Homes in Ashland County

Ashland County is a place of houses on their own lots: 76% of its 9,402 homes are detached single-family houses, against 66% across Wisconsin. Half of its homes were built before 1972, close to Wisconsin's 1975: 40% date from before 1960 and 16% from 2000 or later. 72% of occupied homes are lived in by their owner (Wisconsin: 68%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Ashland County, Wisconsin, 2019 to 2023
HomesAshland CountyWisconsin
Housing units9,4022,750,750
Detached houses76%66%
In buildings of 5 or more8%17%
Mobile homes7%3%
Built before 196040%34%
Built since 200016%20%
Middle year built19721975
Owner-occupied72%68%

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