Locations and reports
Radon Levels in Wisconsin
What this means for you
- Your area: EPA rates 28 of Wisconsin's 72 classified counties Zone 1, the highest of its three radon zones. Zones are predictions for whole counties, and homes with elevated levels occur in all three zones.
- Local tests: CDC publishes Wisconsin's radon test results by county. Open your county below to see its figures.
- Your home: The only way to know your home’s level is to test it.
pCi/L (picocuries per liter) is the unit radon is measured in. EPA recommends fixing a home at 4 pCi/L or above, its action level.
For Wisconsin, EPA's Map of Radon Zones places 28 of its 72 classified counties in Zone 1, highest predicted potential, a prediction for each county as a whole. Radon levels vary from home to home, so only a test measures the level in yours.
Predicted: EPA radon zone
72 of 72 counties classified
EPA classifies counties, not states. Of the 72 counties in Wisconsin with a zone, 28 are in Zone 1 and 44 in Zone 2.
- Zone 1: Highest predicted potentialgreater than 4 pCi/L28 of 72 counties · 38.9%
- Zone 2: Moderate predicted potential2 to 4 pCi/L44 of 72 counties · 61.1%
An EPA radon zone describes predicted potential across a whole county. It is not intended to determine whether any individual home should be tested, and homes with elevated levels occur in all three zones. EPA recommends testing every home regardless of zone, and testing is the only way to know the radon level in a specific building.
This is a county-level geologic prediction. It is not a measurement of any address, and houses with elevated radon are found in all three zones.
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
CDC publishes Wisconsin's radon test figures by county: 72 of its 72 counties have one. Each county's share is in the county list.
Wisconsin, In figures
Wisconsin in figures
What the published data says about Wisconsin, in words. A zone and a share of tests describe an area, never the level in any one home.
Predicted
PredictedEPA places 28 of Wisconsin's 72 counties in Zone 1 and 44 in Zone 2.
Zone 1 counties, A to Z, begin with Buffalo County, Crawford County and Dane County; the county section below lists all 28.
Compared
Calculated by Radon41139% of Wisconsin's counties with a zone on file are in Zone 1, a larger share than across all U.S. counties (34%). It is a share of counties, not of land, people or homes.
Reported tests
MeasuredCDC has no statewide testing figure for Wisconsin on file here.
72 of the 72 counties have a published county figure; the most tests in each one's latest year were reported for Dane County (2,118 in 2023), Milwaukee County (2,021 in 2023) and Waukesha County (1,379 in 2023).
Local record
Wisconsin's radon program and its page are under Local resources.
4 cities have a page setting the figures of the counties it lies in side by side: Madison, Green Bay, Oshkosh and Wausau.
Wisconsin, Counties
Wisconsin counties by EPA zone
PredictedAll 72 counties, by the zone EPA predicts for each. Every county has its own report.
Zone 1: highest predicted potential28
- Buffalo County53.6% of reported tests at or above 4 pCi/L, 2023
- Crawford County53.9% of reported tests at or above 4 pCi/L, 2023
- Dane County34.9% of reported tests at or above 4 pCi/L, 2023
- Dodge County54.9% of reported tests at or above 4 pCi/L, 2023
- Door County42.3% of reported tests at or above 4 pCi/L, 2023
- Fond du Lac County19.6% of reported tests at or above 4 pCi/L, 2023
- Grant County48.3% of reported tests at or above 4 pCi/L, 2023
- Green County33.6% of reported tests at or above 4 pCi/L, 2023
- Green Lake County40.5% of reported tests at or above 4 pCi/L, 2023
- Iowa County61.0% of reported tests at or above 4 pCi/L, 2023
- Jefferson County44.3% of reported tests at or above 4 pCi/L, 2023
- Lafayette County52.2% of reported tests at or above 4 pCi/L, 2023
- Langlade County65.8% of reported tests at or above 4 pCi/L, 2023
- Marathon County51.9% of reported tests at or above 4 pCi/L, 2023
- Menominee County100.0% of reported tests at or above 4 pCi/L, 2023
- Pepin County15.4% of reported tests at or above 4 pCi/L, 2023
- Pierce County30.9% of reported tests at or above 4 pCi/L, 2023
- Portage County35.6% of reported tests at or above 4 pCi/L, 2023
- Richland County33.3% of reported tests at or above 4 pCi/L, 2023
- Rock County49.9% of reported tests at or above 4 pCi/L, 2023
- Shawano County57.0% of reported tests at or above 4 pCi/L, 2023
- St. Croix County37.4% of reported tests at or above 4 pCi/L, 2023
- Vernon County47.5% of reported tests at or above 4 pCi/L, 2023
- Walworth County37.9% of reported tests at or above 4 pCi/L, 2023
- Washington County47.9% of reported tests at or above 4 pCi/L, 2023
- Waukesha County43.2% of reported tests at or above 4 pCi/L, 2023
- Waupaca County52.8% of reported tests at or above 4 pCi/L, 2023
- Wood County18.3% of reported tests at or above 4 pCi/L, 2023
Zone 2: moderate predicted potential44
- Adams County20.8% of reported tests at or above 4 pCi/L, 2023
- Ashland County29.3% of reported tests at or above 4 pCi/L, 2023
- Barron County34.7% of reported tests at or above 4 pCi/L, 2023
- Bayfield County5.7% of reported tests at or above 4 pCi/L, 2023
- Brown County23.0% of reported tests at or above 4 pCi/L, 2023
- Burnett County23.1% of reported tests at or above 4 pCi/L, 2023
- Calumet County51.6% of reported tests at or above 4 pCi/L, 2023
- Chippewa County35.7% of reported tests at or above 4 pCi/L, 2023
- Clark County25.3% of reported tests at or above 4 pCi/L, 2023
- Columbia County28.8% of reported tests at or above 4 pCi/L, 2023
- Douglas County9.1% of reported tests at or above 4 pCi/L, 2023
- Dunn County37.4% of reported tests at or above 4 pCi/L, 2023
- Eau Claire County32.7% of reported tests at or above 4 pCi/L, 2023
- Florence County43.8% of reported tests at or above 4 pCi/L, 2023
- Forest County40.0% of reported tests at or above 4 pCi/L, 2023
- Iron County22.2% of reported tests at or above 4 pCi/L, 2023
- Jackson County38.7% of reported tests at or above 4 pCi/L, 2023
- Juneau County10.0% of reported tests at or above 4 pCi/L, 2023
- Kenosha County42.4% of reported tests at or above 4 pCi/L, 2023
- Kewaunee County44.6% of reported tests at or above 4 pCi/L, 2023
- La Crosse County31.4% of reported tests at or above 4 pCi/L, 2023
- Lincoln County23.5% of reported tests at or above 4 pCi/L, 2023
- Manitowoc County31.1% of reported tests at or above 4 pCi/L, 2023
- Marinette County44.3% of reported tests at or above 4 pCi/L, 2023
- Marquette County15.0% of reported tests at or above 4 pCi/L, 2023
- Milwaukee County20.2% of reported tests at or above 4 pCi/L, 2023
- Monroe County22.5% of reported tests at or above 4 pCi/L, 2023
- Oconto County52.3% of reported tests at or above 4 pCi/L, 2023
- Oneida County40.7% of reported tests at or above 4 pCi/L, 2023
- Outagamie County40.7% of reported tests at or above 4 pCi/L, 2023
- Ozaukee County45.8% of reported tests at or above 4 pCi/L, 2023
- Polk County33.6% of reported tests at or above 4 pCi/L, 2023
- Price County36.7% of reported tests at or above 4 pCi/L, 2023
- Racine County37.3% of reported tests at or above 4 pCi/L, 2023
- Rusk County38.6% of reported tests at or above 4 pCi/L, 2023
- Sauk County41.1% of reported tests at or above 4 pCi/L, 2023
- Sawyer County42.6% of reported tests at or above 4 pCi/L, 2023
- Sheboygan County42.9% of reported tests at or above 4 pCi/L, 2023
- Taylor County18.9% of reported tests at or above 4 pCi/L, 2023
- Trempealeau County42.0% of reported tests at or above 4 pCi/L, 2023
- Vilas County21.7% of reported tests at or above 4 pCi/L, 2023
- Washburn County44.9% of reported tests at or above 4 pCi/L, 2023
- Waushara County25.4% of reported tests at or above 4 pCi/L, 2023
- Winnebago County42.4% of reported tests at or above 4 pCi/L, 2023
Wisconsin, Cities
Cities in Wisconsin with their own page
Radon data is published by county, not by city. Each city page sets the figures of the counties the city lies in side by side.
Wisconsin, Local resources
Local resources in Wisconsin
Who to ask in Wisconsin: the state's radon program, test kits and professionals.
Wisconsin's radon program
Wisconsin Department of Health Services
Wisconsin’s radon program answers questions about testing, mitigation and the rules where you live.
- Phone
- 1-888-569-7236
- 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.
Test kits
The program says: We recommend starting with your regional Radon Information Center since many centers provide test kits for free or reduced cost, and often with laboratory fees covered.
Radon professionals
13 professionals are listed in Wisconsin.
Professionals in WisconsinWisconsin, Questions
Questions about radon in Wisconsin
Common questions9 questions, answered from the figures above
Is radon a problem in Wisconsin?
EPA's Map of Radon Zones places 28 of the 72 Wisconsin counties it classifies in Zone 1, the highest predicted potential, 44 in Zone 2 and 0 in Zone 3. An EPA radon zone describes predicted potential across a whole county. It is not intended to determine whether any individual home should be tested, and homes with elevated levels occur in all three zones. EPA recommends testing every home regardless of zone, and testing is the only way to know the radon level in a specific building.
Who does radon mitigation in Wisconsin?
Radon411's Wisconsin directory lists 13 certified radon companies. EPA recommends having a qualified contractor fix a home with a radon problem, because lowering high radon levels takes technical knowledge and special skills, and some states require the work to be done by a licensed or certified professional.
How radon mitigation worksWhat mitigation costsRadon professionals in Wisconsin
Which Wisconsin counties are in EPA radon Zone 1?
28 counties are in Zone 1: Buffalo County, Crawford County, Dane County, Dodge County, Door County, Fond du Lac County, Grant County, Green County, and 20 more in the county table on this page. Zone 1 is EPA's class for highest predicted potential, a predicted average indoor screening level greater than 4 pCi/L. A zone is a prediction for a county, not a measurement of any home.
Radon in Buffalo CountyRadon in Crawford CountyRadon in Dane County
How do I get a radon test in Wisconsin?
EPA says you can test your home yourself or hire a qualified radon test company, and that either approach takes only a small amount of time and effort. The Wisconsin radon program is the place to ask about certified testers and any test kit offer it runs.
How to test a homeFree and low-cost kits by stateWisconsin radon program
Which Wisconsin counties have the highest radon?
72 of Wisconsin's 72 counties have an EPA radon zone published here. Radon411 will not rank counties on data it does not hold, and a zone is a prediction for an area rather than a measurement of any building.
What share of radon tests in Wisconsin are high?
CDC has published no statewide radon testing statistics for Wisconsin, so we cannot give a figure. Where CDC does publish one, the percentage describes radon tests reported to CDC, not homes.
Which EPA region is Wisconsin in?
Wisconsin is in EPA Region 5: Great Lakes.
Do I need to test my home in Wisconsin?
Yes, wherever you live in the state. Testing is the only way to know the radon level in a specific building. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L.
Why does this page show coverage rather than one radon level for Wisconsin?
A statewide figure averages counties with very different geology and very different numbers of reported tests, so it hides more than it shows. The county report is the level at which the EPA zone, the geologic potential and the reported testing statistics are actually published, which is why the county table above links to every one of them.
What these figures mean if you own, buy, sell or rent
The zone counts on this page describe counties across Wisconsin. They are predictions for areas, and none of them measures your building.
- How to test a home
If you own your home
Test the lowest lived-in level; a short-term kit screens in days, a long-term kit reflects the year.
- Buying a house: radon guide
If you are buying
Ask for past results and any system's post-mitigation test, and test during the sale.
- Selling a house: radon guide
If you are selling
Testing before you list puts the timing in your hands; disclosure rules differ by state.
- Radon in rental homes
If you rent, or rent out a home
A tenant can test; a fix is the owner's to make, and duties differ by state.
How long a test has to run, under what conditions, and what EPA says a result means: the testing standard, in full.
Wisconsin, Products
Testing and mitigation products
Whatever the figures for Wisconsin show, only a test tells you about one home.
Testing
- Short-term test kitsPassive detectors exposed for a few days under closed-building conditions, then analyzed by a lab.
- Long-term test kitsDetectors exposed for more than 90 days, for a closer picture of the annual average.
- Continuous monitorsPowered devices that log radon on a repeating cycle, often used for transaction tests.
- Digital detectorsConsumer devices that display a running radon reading without a lab.
- Water radon testsKits for radon dissolved in well water, analyzed by a lab.
Mitigation
- Mitigation fansThe inline fan that keeps a soil depressurization system running, sized by the installer.
- System indicatorsU-tube manometers and fan alarms that show whether a mitigation system is still working.
- Sealing materialsCrack, joint and sump sealing used alongside a mitigation system, not instead of one.
Wisconsin / Next steps
What to do next
Learn
Know what radon is
What radon is, how it gets indoors, and why a county zone is not a reading for your home.
Learn about radonTest
Test the building you live in
Short-term or long-term, where the device goes, and closed-house conditions.
How to testFix
Bring a high level down
How a mitigation system works, and the retest that confirms it.
How mitigation worksFind a pro
Hire a certified professional
Measurement and mitigation professionals by state, with their certifications.
Find a professional
Informational. Follow EPA guidance. EPA says all radon tests should be taken for a minimum of 48 hours, with windows and doors closed from 12 hours before a short-term test.