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Wisconsin Radon Map and Levels by County

Wisconsin's counties span EPA Zones 1 and 2. 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

    46.9%

    11.2 pts above U.S.

    Wisconsin
    46.9%
    U.S.
    35.7%

    68,104 tests across 72 counties, 2008 to 2017

  • Rank among states

    7 of 47

    Ten highest states

    Wisconsin
    46.9%
    North Dakota
    59.3%

    By share, every state pooled the same way, 2008 to 2017

  • Counties in EPA Zone 1

    28 of 72

    Some at highest potential

    Zone 1
    28
    Zone 2
    44

    Most counties sit in Zone 2; Zone 1 is the highest potential

  • Highest county

    68.0%

    Langlade County

    Langlade
    68.0%
    Ashland
    12.8%

    Counties with 30+ tests, 2008 to 2017

Read a result for Wisconsin

Starts at EPA's action level

4.0pCi/L

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

EPA’s reading of 4.0 pCi/L

At or above 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 at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. 46.9% of Wisconsin's reported tests reached 4 pCi/L, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Wisconsin, At a glance

Wisconsin at a glance

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 predicts a whole county. It is not intended to determine whether any individual home should be tested: homes with elevated levels occur in all three zones, and EPA recommends testing every home regardless of zone.

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

CDC test figures, county by county

CDC publishes Wisconsin's radon test figures by county: 72 of its 72 counties have one. Each one's share is in the county list.

How to read these figures

Wisconsin, Compared

Wisconsin radon figures, compared

Calculated by Radon411
Wisconsin, 2008 to 2017, laboratory
46.9%
of 68,104 tests at or above 4 pCi/L, pooled
Against the U.S.
+11.2points
35.7% pooled
Rank among the states
7 of 47
1 is the highest share
Counties with 30 or more tests
71
Highest
68.0%
Langlade County
Lowest
12.8%
Ashland County

Pooled across 72 counties, 46.9% of the 68,104 radon tests reported to CDC for Wisconsin over the 2008 to 2017 laboratory totals were at or above 4 pCi/L: close to half or more. That is 7th of 47 states with county figures for the period; Colorado (47.0%) above it and Montana (45.5%) below.

Its 71 counties with 30 or more tests run from 12.8% in Ashland County to 68.0% in Langlade County; in 27 of them half or more of the reported tests reached 4 pCi/L. By band, 27 counties at 50% or more, 36 counties at 30% to 50%, 6 counties at 15% to 30%, 2 counties at 5% to 15%.

The national pool for the same period is 35.7%, so Wisconsin runs 11.2 points above the country. EPA's 1993 map puts 28 of its 72 classified counties in Zone 1; against that, 46.9% of the tests reported since reached 4 pCi/L.

Across its 4 overlapping ten-year totals, the share went from 47.8% (2005 to 2014) to 46.9% (2008 to 2017), within 2 points, with 2006 to 2015 the highest at 48.2%.

Wisconsin ranked among 47 states by pooled share of tests at or above 4 pCi/L, 2008 to 2017, laboratory
StateRankCountiesTestsAt or above 4 pCi/L
Nebraska2 of 479342,78258.5%
South Dakota3 of 47626,27558.5%
Iowa4 of 479995,24558.5%
Ohio5 of 478898,84052.3%
Colorado6 of 476396,36747.0%
Wisconsin7 of 477268,10446.9%
Montana8 of 47519,89345.5%
Wyoming9 of 47237,63844.3%
Kentucky10 of 4712028,79343.7%
Minnesota11 of 4787130,91243.4%
Illinois12 of 47102108,90943.1%
Wisconsin's highest and lowest counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/L
Langlade County1 of 7122268.0%
Grant County2 of 7163664.0%
Dodge County3 of 711,00463.3%
Iowa County4 of 7141363.2%
Waupaca County5 of 7178262.7%
Lafayette County6 of 7111361.9%
Vernon County7 of 7141560.7%
Calumet County8 of 7144359.8%
Crawford County9 of 7116059.4%
Portage County10 of 7159556.5%
Ashland County71 of 7126612.8%
Marquette County70 of 7112714.2%
Adams County69 of 7111821.2%
Douglas County68 of 7123124.2%
Sawyer County67 of 7112525.6%
Wisconsin's counties with 30 or more tests, by their own share at or above 4 pCi/L, 2008 to 2017, laboratory
ShareCountiesTheir testsFor example
50% or more2729,107Langlade County, Grant County, Dodge County
30% to 50%3637,590Oconto County, Racine County, Pepin County
15% to 30%61,012Iron County, Marinette County, Juneau County
5% to 15%2393Marquette County, Ashland County
Under 5%00None
Wisconsin ten-year laboratory totals, pooled, against the United States
PeriodCountiesTestsAt or above 4 pCi/LUnited StatesChange from the row before
2008 to 20177268,10446.9%35.7%−0.3 points
2007 to 20167266,03047.2%35.8%−1.0 points
2006 to 20157261,34948.2%36.3%+0.4 points
2005 to 20147256,77547.8%36.0%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period. CDC publishes no state or national figure.

Wisconsin, Counties

Wisconsin counties by EPA zone

Predicted

Wisconsin's radon map, then all 72 counties by EPA's zone, the highest reported share of tests at or above 4 pCi/L first; each has its own report.

Wisconsin radon map by county: EPA radon zones. Map of Wisconsin's 72 counties shaded by EPA radon zone: Zone 1 in red-orange, Zone 2 in amber. 28 in Zone 1, 44 in Zone 2, 0 in Zone 3.
Wisconsin radon map by countyEPA radon zones for Wisconsin's counties: 28 counties in Zone 1, 44 counties in Zone 2, 0 counties in Zone 3.A prediction for each county, not a reading of any home; elevated homes occur in all three zones.

The 12 highest in Wisconsin, 2008 to 2017

Zone 1: highest predicted potential28

Local help

Wisconsin, Local resources

Local resources in Wisconsin

Who to ask in Wisconsin: its radon program, test kits and professionals.

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

Wisconsin, Questions

Questions about radon in Wisconsin

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. Pooled from 72 counties, 46.9% of the 68,104 radon tests reported to CDC over the 2008 to 2017 laboratory totals were at or above 4 pCi/L, 7th of 47 states.

Who does radon mitigation in Wisconsin?

19 radon businesses are listed for Wisconsin, for testing, mitigation or both; each listing names the licensing list it was read from.

Which Wisconsin counties are in EPA radon Zone 1?

Zone 1 holds 28 counties in Wisconsin; the first 8 by name are Buffalo County, Crawford County, Dane County, Dodge County, Door County, Fond du Lac County, Grant County, Green County, the rest in the county table on this page.

Which Wisconsin counties have the highest radon?

Langlade County 68.0% (222 tests) leads Wisconsin by the share of reported tests at or above 4 pCi/L, 2008 to 2017, laboratory, then Grant County 64.0% (636 tests), Dodge County 63.3% (1,004 tests), Iowa County 63.2% (413 tests), Waupaca County 62.7% (782 tests).

Which EPA region is Wisconsin in?

Wisconsin is in EPA Region 5: Great Lakes.

Products

Wisconsin, Products

Testing a home in Wisconsin

46.9% of the 68,104 tests reported to CDC for Wisconsin over the 2008 to 2017 laboratory totals reached 4 pCi/L: a short-term kit (2 to 90 days) gives a first answer in days, a long-term test the year-round average. A short-term kit (2 to 90 days) is the quick first check for a home in Wisconsin; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Wisconsin homes, compared

Explore

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.