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Radon zones in Wisconsin

The EPA assigns every county in Wisconsin to one of three radon potential zones. 28 are in Zone 1, the highest category, home to about 42% of the state's residents.

72
Counties
28
Zone 1 counties
Predicted average above 4 pCi/L
44
Zone 2 counties
Predicted average 2-4 pCi/L
0
Zone 3 counties
Predicted average below 2 pCi/L

The map

Radon potential across Wisconsin

Every county in Wisconsin, filled by the zone the EPA assigns it. Zones follow geology rather than county lines, so the colour usually changes where the bedrock does, not where the border is.

Zone 1 · 28Zone 2 · 44Zone 3 · 0

Hover a county · click to open it

County by county

All 72 Wisconsin counties

Zone 1 · > 4 pCi/LZone 2 · 2 - 4 pCi/LZone 3 · < 2 pCi/L
CountyZonePopulationCOPDSmokingLung ca. deaths
Buffalo County113k7.8%15.0%33.3
Crawford County116k8.8%16.4%45.6
Dane County1575k4.4%9.8%24.4
Dodge County188k7.0%14.9%35.1
Door County131k7.5%11.9%29.0
Fond du Lac County1104k6.9%14.8%27.1
Grant County151k7.3%15.0%33.1
Green County137k6.8%13.6%35.0
Green Lake County119k8.8%16.0%32.8
Iowa County124k6.8%13.8%39.0
Jefferson County186k6.4%13.4%27.1
Lafayette County117k8.0%15.9%31.1
Langlade County119k9.2%17.2%45.0
Marathon County1139k6.7%14.3%29.0
Menominee County14,2268.9%23.4%84.6
Pepin County17,4417.4%14.2% -
Pierce County143k5.8%13.0%26.7
Portage County171k6.1%12.8%26.5
Richland County117k8.9%16.4%34.9
Rock County1164k6.8%14.7%38.8
Shawano County141k8.2%16.7%30.0
St. Croix County197k5.5%12.6%25.3
Vernon County131k8.5%16.1%27.8
Walworth County1106k6.4%12.8%31.2
Washington County1138k5.9%12.1%26.0
Waukesha County1413k5.2%10.3%27.3
Waupaca County151k7.8%15.7%34.5
Wood County174k7.7%15.5%29.1
Adams County221k10.1%17.5%40.9
Ashland County216k8.6%17.3%38.7
Barron County247k8.2%15.4%39.4
Bayfield County217k7.9%13.3%25.1
Brown County2271k6.1%13.4%27.1
Burnett County217k9.7%16.1%40.9
Calumet County253k5.9%12.9%22.3
Chippewa County267k7.2%15.6%30.4
Clark County235k9.0%18.3%40.7
Columbia County258k6.9%14.4%29.5
Douglas County244k7.0%14.3%38.5
Dunn County246k6.2%13.7%29.0
Eau Claire County2108k5.8%12.6%29.4
Florence County24,6828.5%14.5% -
Forest County29,32510.2%19.9%38.9
Iron County26,2289.1%14.8%47.8
Jackson County221k8.5%17.7%35.3
Juneau County227k9.1%18.5%42.8
Kenosha County2167k6.5%14.5%39.2
Kewaunee County221k7.3%14.7%25.9
La Crosse County2120k6.0%12.6%32.6
Lincoln County228k8.5%16.0%33.3
Manitowoc County281k7.7%14.9%36.6
Marinette County242k8.5%16.1%33.0
Marquette County216k9.5%17.0%42.7
Milwaukee County2916k6.7%14.6%36.1
Monroe County246k8.2%17.1%36.1
Oconto County240k7.9%15.7%33.8
Oneida County238k7.9%14.1%35.8
Outagamie County2193k5.9%12.7%29.2
Ozaukee County293k5.4%10.3%22.3
Polk County246k7.3%14.3%35.8
Price County214k9.5%16.7%35.0
Racine County2197k6.7%14.7%37.5
Rusk County214k9.8%17.5%38.6
Sauk County266k7.0%14.9%39.0
Sawyer County219k9.3%17.3%42.1
Sheboygan County2118k6.5%13.7%29.5
Taylor County220k8.4%16.3%26.8
Trempealeau County231k7.6%15.8%32.3
Vilas County224k8.3%14.2%32.6
Washburn County217k8.9%15.7%38.1
Waushara County225k8.7%16.5%36.5
Winnebago County2172k6.4%14.2%31.0

Zones from the EPA Map of Radon Zones. COPD and smoking are CDC PLACES model-based estimates of adult prevalence. Lung cancer death rates are age-adjusted deaths per 100,000 per year, 2019-2023, from NCI State Cancer Profiles. A dash means the source does not report a value for that county.

Highest potential

Zone 1 counties in Wisconsin

These 28 counties have a predicted average indoor radon screening level above the EPA action level. The EPA recommends every home in them be tested.

Other states

Radon zones elsewhere