Radon levels in Wisconsin: Moderate
The model predicts a population-weighted basement average of 2.0 pCi/L across Wisconsin's 72 counties - close to the US average of 1.8 pCi/L. Above-ground floors average 1.4 pCi/L.
Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.
28 / 72
EPA Zone 1 counties (39%)
44 / 0
Zone 2 / Zone 3 counties
0
counties predicted ≥ 4 pCi/L
0.1%
of ZIP codes predicted ≥ 4 pCi/L
Wisconsin counties by predicted radon
Sorted highest to lowest predicted basement average. 72 counties.
| County | Predicted basement | Upstairs | Grade | EPA zone | ZIPs |
|---|---|---|---|---|---|
| Lafayette County | 3.4 pCi/L | 2.2 | Moderate | EPA Zone 1 | 8 |
| Marathon County | 3.4 pCi/L | 2.1 | Moderate | EPA Zone 1 | 15 |
| Grant County | 3.3 pCi/L | 2.2 | Moderate | EPA Zone 1 | 18 |
| Vernon County | 3.0 pCi/L | 2.1 | Moderate | EPA Zone 1 | 10 |
| Green County | 3.0 pCi/L | 2.1 | Moderate | EPA Zone 1 | 7 |
| Langlade County | 3.0 pCi/L | 2.3 | Moderate | EPA Zone 1 | 8 |
| Iowa County | 3.0 pCi/L | 2.1 | Moderate | EPA Zone 1 | 11 |
| Crawford County | 3.0 pCi/L | 1.9 | Moderate | EPA Zone 1 | 7 |
| Pierce County | 2.8 pCi/L | 2.0 | Moderate | EPA Zone 1 | 10 |
| Portage County | 2.8 pCi/L | 1.8 | Moderate | EPA Zone 1 | 10 |
| Dodge County | 2.8 pCi/L | 2.1 | Moderate | EPA Zone 1 | 16 |
| Buffalo County | 2.7 pCi/L | 1.6 | Moderate | EPA Zone 1 | 5 |
| Chippewa County | 2.7 pCi/L | 1.4 | Moderate | EPA Zone 2 | 9 |
| Fond du Lac County | 2.7 pCi/L | 1.8 | Moderate | EPA Zone 1 | 14 |
| Lincoln County | 2.7 pCi/L | 1.4 | Moderate | EPA Zone 2 | 4 |
| Waupaca County | 2.7 pCi/L | 1.7 | Moderate | EPA Zone 1 | 9 |
| Green Lake County | 2.6 pCi/L | 1.8 | Moderate | EPA Zone 1 | 5 |
| Richland County | 2.6 pCi/L | 1.7 | Moderate | EPA Zone 1 | 5 |
| Pepin County | 2.6 pCi/L | 1.6 | Moderate | EPA Zone 1 | 4 |
| St. Croix County | 2.6 pCi/L | 1.9 | Moderate | EPA Zone 1 | 11 |
| Rock County | 2.6 pCi/L | 1.8 | Moderate | EPA Zone 1 | 11 |
| Menominee County | 2.6 pCi/L | 2.0 | Moderate | EPA Zone 1 | 2 |
| Trempealeau County | 2.6 pCi/L | 1.6 | Moderate | EPA Zone 2 | 10 |
| Winnebago County | 2.5 pCi/L | 1.3 | Moderate | EPA Zone 2 | 8 |
| Florence County | 2.5 pCi/L | 1.4 | Moderate | EPA Zone 2 | 2 |
| Walworth County | 2.5 pCi/L | 1.9 | Moderate | EPA Zone 1 | 11 |
| Calumet County | 2.4 pCi/L | 1.5 | Moderate | EPA Zone 2 | 7 |
| Barron County | 2.4 pCi/L | 1.3 | Moderate | EPA Zone 2 | 10 |
| Clark County | 2.3 pCi/L | 1.4 | Moderate | EPA Zone 2 | 14 |
| Outagamie County | 2.3 pCi/L | 1.3 | Moderate | EPA Zone 2 | 13 |
| Columbia County | 2.3 pCi/L | 1.5 | Moderate | EPA Zone 2 | 10 |
| Eau Claire County | 2.3 pCi/L | 1.3 | Moderate | EPA Zone 2 | 7 |
| Wood County | 2.3 pCi/L | 1.7 | Moderate | EPA Zone 1 | 12 |
| Door County | 2.3 pCi/L | 1.5 | Moderate | EPA Zone 1 | 9 |
| Taylor County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 7 |
| Polk County | 2.2 pCi/L | 1.3 | Moderate | EPA Zone 2 | 14 |
| Shawano County | 2.2 pCi/L | 1.5 | Moderate | EPA Zone 1 | 12 |
| La Crosse County | 2.2 pCi/L | 1.4 | Moderate | EPA Zone 2 | 9 |
| Waushara County | 2.2 pCi/L | 1.1 | Moderate | EPA Zone 2 | 10 |
| Oneida County | 2.2 pCi/L | 1.2 | Moderate | EPA Zone 2 | 8 |
| Jefferson County | 2.2 pCi/L | 1.8 | Moderate | EPA Zone 1 | 10 |
| Rusk County | 2.2 pCi/L | 1.2 | Moderate | EPA Zone 2 | 7 |
| Forest County | 2.1 pCi/L | 1.2 | Moderate | EPA Zone 2 | 7 |
| Juneau County | 2.1 pCi/L | 1.2 | Moderate | EPA Zone 2 | 7 |
| Vilas County | 2.1 pCi/L | 1.1 | Moderate | EPA Zone 2 | 11 |
| Price County | 2.1 pCi/L | 1.3 | Moderate | EPA Zone 2 | 8 |
| Washburn County | 2.1 pCi/L | 1.2 | Moderate | EPA Zone 2 | 7 |
| Jackson County | 2.1 pCi/L | 1.2 | Moderate | EPA Zone 2 | 6 |
| Kenosha County | 2.1 pCi/L | 1.2 | Moderate | EPA Zone 2 | 10 |
| Adams County | 2.0 pCi/L | 1.1 | Moderate | EPA Zone 2 | 6 |
| Monroe County | 2.0 pCi/L | 1.2 | Moderate | EPA Zone 2 | 7 |
| Sauk County | 2.0 pCi/L | 1.3 | Moderate | EPA Zone 2 | 12 |
| Dunn County | 2.0 pCi/L | 1.2 | Low | EPA Zone 2 | 9 |
| Washington County | 2.0 pCi/L | 1.7 | Low | EPA Zone 1 | 11 |
| Brown County | 2.0 pCi/L | 1.1 | Low | EPA Zone 2 | 13 |
| Oconto County | 1.9 pCi/L | 1.2 | Low | EPA Zone 2 | 12 |
| Marquette County | 1.9 pCi/L | 1.0 | Low | EPA Zone 2 | 6 |
| Racine County | 1.9 pCi/L | 1.2 | Low | EPA Zone 2 | 12 |
| Kewaunee County | 1.9 pCi/L | 1.1 | Low | EPA Zone 2 | 4 |
| Burnett County | 1.8 pCi/L | 1.1 | Low | EPA Zone 2 | 6 |
| Iron County | 1.8 pCi/L | 1.0 | Low | EPA Zone 2 | 7 |
| Sawyer County | 1.8 pCi/L | 1.2 | Low | EPA Zone 2 | 7 |
| Dane County | 1.8 pCi/L | 1.4 | Low | EPA Zone 1 | 32 |
| Bayfield County | 1.8 pCi/L | 1.1 | Low | EPA Zone 2 | 10 |
| Marinette County | 1.6 pCi/L | 1.1 | Low | EPA Zone 2 | 12 |
| Manitowoc County | 1.6 pCi/L | 1.1 | Low | EPA Zone 2 | 10 |
| Waukesha County | 1.6 pCi/L | 1.4 | Low | EPA Zone 1 | 25 |
| Ashland County | 1.5 pCi/L | 1.0 | Low | EPA Zone 2 | 8 |
| Ozaukee County | 1.5 pCi/L | 1.2 | Low | EPA Zone 2 | 8 |
| Douglas County | 1.5 pCi/L | 0.9 | Low | EPA Zone 2 | 9 |
| Sheboygan County | 1.5 pCi/L | 1.0 | Low | EPA Zone 2 | 13 |
| Milwaukee County | 1.3 pCi/L | 0.8 | Low | EPA Zone 2 | 35 |
Wisconsin radon questions
- Is radon high in Wisconsin?
- Wisconsin's population-weighted predicted basement average is 2.0 pCi/L, close to the US average of 1.8. 0 of its 72 modeled counties are predicted at or above the EPA action level of 4 pCi/L, 52 are in the 2-4 "consider fixing" range and 20 are below 2. 0.1% of Wisconsin ZIP codes are predicted at 4 or higher.
- Which Wisconsin county has the highest radon?
- Lafayette County has the highest predicted basement average in Wisconsin at 3.4 pCi/L (EPA Zone 1). The lowest is Milwaukee County at 1.3 pCi/L. These are modeled area averages; individual homes in any county can test far higher.
- How many EPA Zone 1 counties are in Wisconsin?
- 28 of Wisconsin's 72 counties (39%) are EPA Zone 1 (highest potential), 44 are Zone 2 and 0 are Zone 3. The EPA zone map dates from 1993; the predicted values on this page come from a 2001-2021 model built on millions of actual tests, so the two can disagree for a given county.
- Should I test for radon in Wisconsin?
- Yes - with some urgency. Wisconsin's predicted average is in the moderate range, and 69.3% of its ZIP codes are predicted at 2 pCi/L or higher. A short-term charcoal kit or a continuous digital monitor will tell you your actual level within days.
Wisconsin radon program
Many states offer free or discounted test kits and keep lists of certified mitigators. Find the Wisconsin radon office through the EPA state radon contacts page. Then read how to test and what mitigation costs.