Wisconsin: 72 counties covered
Of 72 rated Wisconsin counties, 28 are in EPA's highest radon-potential zone (Zone 1) — but every county page links to testing guidance regardless of zone, because a county rating is a county-wide average, not a reading for any one house.
- Milwaukee County
- Dane County
- Waukesha County
- Brown County
- Racine County
- Outagamie County
- Winnebago County
- Kenosha County
- Rock County
- Marathon County
- Washington County
- La Crosse County
- Sheboygan County
- Eau Claire County
- Walworth County
- Fond du Lac County
- St. Croix County
- Ozaukee County
- Dodge County
- Jefferson County
- Manitowoc County
- Wood County
- Portage County
- Chippewa County
- Sauk County
- Columbia County
- Calumet County
- Grant County
- Waupaca County
- Barron County
- Monroe County
- Dunn County
- Polk County
- Douglas County
- Pierce County
- Marinette County
- Shawano County
- Oconto County
- Oneida County
- Green County
- Clark County
- Vernon County
- Trempealeau County
- Door County
- Lincoln County
- Juneau County
- Waushara County
- Iowa County
- Vilas County
- Adams County
- Jackson County
- Kewaunee County
- Taylor County
- Langlade County
- Green Lake County
- Sawyer County
- Lafayette County
- Burnett County
- Richland County
- Washburn County
- Bayfield County
- Ashland County
- Crawford County
- Marquette County
- Rusk County
- Price County
- Buffalo County
- Forest County
- Pepin County
- Iron County
- Florence County
- Menominee County