Wisconsin Radon Map, Levels & Testing Guide
Browse the 72 listed county pages surfaced for Wisconsin. Open a listed county to compare its EPA zone, source caveats, testing meaning, and when mitigation pricing becomes worth checking.
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Official Evidence in Wisconsin
72 of 72 listed counties have official evidence
Open a county page to see the official source context: measurement fields, local burden, state percentile, and the next step for no reading, 2.0-3.9, or 4.0+ pCi/L.
100%
covered
Measured
72
State source
72
CDC source
0
Needs source detail
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Measured Risk Leaders in Wisconsin
County rankings from actual reported radon tests
These lists rank the visible Wisconsin county pages by measured radon signals, not by the EPA zone label alone. Use them to spot where the state hub has a real data story before opening individual county pages.
72
measured counties
State-level evidence read
This hub has measured high-burden counties, so the first click should be evidence-led.
The state hub is now doing a decision job: it separates first-click counties, retest counties, and lower-signal counties from 72 visible county measurement rows. 49 counties cross the high measured-burden band, so those pages should answer testing and 4.0+ action questions most directly.
First-click counties
Open Marathon County first when you need the strongest local answer. It is tagged Test-now from 67.0% 4.0+ - 14.6 pCi/L primary - 4,116 tests. 57 visible measured counties are elevated or high enough to review before lower-signal counties.
Buyer/seller lane
Buyer/seller lane: start with the elevated or high counties, require a fresh lowest-level test, and turn any 4.0+ property result into quote or credit math. The hub has 72 state-source county rows to support that routing.
Retest lane
Retest lane: 2.0-3.9 pCi/L deserves more caution in the elevated/high county set than in lower-signal counties. The hub should send those users to county pages before product or cost paths.
Best county pages to open first
Start with these local evidence pages
Ranked by measured burden, 4.0+ share, test volume, and whether the EPA zone understates the measurement signal.
Marathon County
WI DHS
67.0% 4.0+ - 14.6 pCi/L primary - 4,116 tests
Marathon County is a first-click page: 67.0% of reported tests at or above 4.0 and 14.6 pCi/L primary result. Route no-reading users to a test now and 4.0+ users to quote or credit planning.
Waukesha County
WI DHS
62.0% 4.0+ - 7.5 pCi/L primary - 8,578 tests
Waukesha County is a first-click page: 62.0% of reported tests at or above 4.0 and 7.5 pCi/L primary result. Route no-reading users to a test now and 4.0+ users to quote or credit planning.
Waupaca County
WI DHS
59.0% 4.0+ - 7.7 pCi/L primary - 1,351 tests
Waupaca County is a first-click page: 59.0% of reported tests at or above 4.0 and 7.7 pCi/L primary result. Route no-reading users to a test now and 4.0+ users to quote or credit planning.
Dodge County
WI DHS
61.1% 4.0+ - 7.3 pCi/L primary - 1,542 tests
Dodge County is a first-click page: 61.1% of reported tests at or above 4.0 and 7.3 pCi/L primary result. Route no-reading users to a test now and 4.0+ users to quote or credit planning.
Highest 4.0+ share
Primary result 14.6 pCi/L - high-end 686.9 pCi/L
WI DHS
Primary result 7.5 pCi/L - high-end 190.0 pCi/L
WI DHS
Primary result 6.7 pCi/L - high-end 246.9 pCi/L
WI DHS
Primary result 7.3 pCi/L - high-end 82.5 pCi/L
WI DHS
Primary result 6.9 pCi/L - high-end 113.5 pCi/L
WI DHS
Highest high-end reading
4.0+ share 67.0% - primary result 14.6 pCi/L
WI DHS
4.0+ share 49.5% - primary result 5.0 pCi/L
WI DHS
4.0+ share 43.5% - primary result 6.7 pCi/L
WI DHS
4.0+ share 53.5% - primary result 5.8 pCi/L
WI DHS
4.0+ share 59.0% - primary result 7.7 pCi/L
WI DHS
Most reported tests
4.0+ share 48.9% - primary result 5.1 pCi/L
WI DHS
4.0+ share 62.0% - primary result 7.5 pCi/L
WI DHS
4.0+ share 50.9% - primary result 5.6 pCi/L
WI DHS
4.0+ share 67.0% - primary result 14.6 pCi/L
WI DHS
4.0+ share 58.4% - primary result 6.9 pCi/L
WI DHS
Measured pattern
Among 72 visible counties with measurement tables, 49 land in the high measured-burden band and 57 land in high or elevated measured-burden bands. That lets this hub rank counties by observed test distribution instead of repeating the EPA map.
Map vs measurements
32 elevated measured counties are not EPA Zone 1. Those are the pages where the actual test distribution matters more than a map-only answer.
Source strategy
All measured rows shown here use state-specific official sources, so this hub can make source-backed county comparisons without leaning on a national fallback.
Already Tested
View Wisconsin Cost Estimates
If you already have a radon result, skip the directory and move straight to local price guidance.
Understand the Number
2.0 vs 4.0 vs 8.0 pCi/L
Use the parent levels guide if you need the plain-English meaning of a radon result before browsing counties.
Need a Number First
Read the Testing Guide
Use the fastest valid radon test setup before you compare quotes or ask whether mitigation is worth it.
Browse Counties
Jump to the Directory
Open your county to see its EPA zone, testing meaning, and the point where mitigation becomes worth pricing.
Official State Resource
Wisconsin radon program and rules
Use the state program link to verify local radon guidance, disclosure language, and contractor credential expectations before you act on an estimate.
Disclosure rule tracked
Wisconsin requires sellers to complete a Real Estate Condition Report that includes known radon test results and environmental hazards.
Credential note
Wisconsin does not require specific radon licensing. NRPP or AARST certification is recommended.
Already tested? Get your itemized mitigation cost estimate.
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