Short-term kit
RA400 short-term liquid scintillation radon test kit, lab fee included
- Lab fee included
Method: Liquid scintillation
In home: 48 to 96 hours
Locations and reports
Radon Levels in Milwaukee County, Wisconsin
EPA puts Milwaukee County in Zone 2, its middle radon zone, and 20.2% of its 2,605 reported radon tests (2023) were at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Share at 4+ pCi/L
20.2%
15.5 pts below WI
- Milwaukee
- 20.2%
- Wisconsin
- 35.7%
2,605 tests, 2023
Median result
1.5pCi/L
Below action level
- Milwaukee
- 1.5 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
2,605
2nd of 69 by tests
- Milwaukee
- 2,605
- Dane
- 2,887
Reported to CDC before any fix, 2023
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Rank in Wisconsin
61 of 69
Lowest quarter
- Milwaukee
- 20.2%
- Langlade
- 65.8%
By share, of 69 with 30+ tests
Read a result for Milwaukee County
Starts at Milwaukee County's median, 1.5 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 1.5 pCi/L
Below 2 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Milwaukee County's median reported result, 2023.
The data
Milwaukee County, At a glance
Milwaukee County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Milwaukee County is a
USGS geologic potential: Moderate across 94% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Milwaukee County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 50.1% |
| 2015 | 52.3% |
| 2016 | 42.6% |
| 2017 | 41.7% |
| 2019 | 34.2% |
| 2020 | 5.4% |
| 2021 | 27.0% |
| 2022 | 36.4% |
| 2023 | 20.2% |
2023: 20.2%. Across these years the share ran from 5.4% to 52.3%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 2,605 tests reported to CDC for Milwaukee County over 2023, many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.
Measured: CDC tracking data. Figure above: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).
Milwaukee County, Compared
Milwaukee County radon figures, compared
Calculated by Radon411Milwaukee County's 2,605 reported tests in 2023 had a middle value of 1.5 pCi/L and a maximum of 59.5 pCi/L, and 20.2% reached 4 pCi/L. Wisconsin as a whole (72 Wisconsin counties, pooled) comes to 35.7%: 15.5 points higher than here.
Among its state's counties it ranks 61st of 69 Wisconsin counties with 30 or more tests for the same period. Statewide for the same period, Langlade County reported the highest share (65.8%) and Bayfield County the lowest (5.7%).
Below the action level, 1,527 tests (58.6%) came in under 2 pCi/L, against 41.4% statewide, and 551 tests (21.2%) fell between 2 and 4, against 23.0% statewide. The busiest year on file was 2020, with 7,137 tests reported; the quietest, 2021, had 1,293.
EPA's 1993 zone map puts Milwaukee County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 94% of the county's land moderate radon potential.
Next door, the shares run from 37.3% in Racine County to 47.9% in Washington County. Over 9 years of annual figures the share fell 29.9 points, from 50.1% in 2014 to 20.2% in 2023; its peak was 52.3% in 2015.
CDC also counts 140 tests taken after mitigation in Milwaukee County for the same period: tests in homes where a fix was already in.
Milwaukee CountyWisconsin, pooled
20.2% % of tests35.7% % of tests
| Year | Tests | Milwaukee County, at or above 4 pCi/L | Wisconsin, pooled |
|---|---|---|---|
| 2014 | 1,544 | 50.1% | 51.1% |
| 2015 | 2,166 | 52.3% | 51.6% |
| 2016 | 1,902 | 42.6% | 45.2% |
| 2017 | 1,572 | 41.7% | 44.8% |
| 2019 | 1,832 | 34.2% | 42.9% |
| 2020 | 7,137 | 5.4% | 27.0% |
| 2021 | 1,293 | 27.0% | 39.9% |
| 2022 | 1,714 | 36.4% | 42.9% |
| 2023 | 2,605 | 20.2% | 35.7% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Milwaukee County, Geology
The ground under Milwaukee County
PredictedMost of the ground under Milwaukee County is one class on USGS's geologic map: 93.7% of its land is moderate radon potential, with 0.3% high and 5.3% low. The map puts 93.7% of Milwaukee County in the area it calls Eastern Ridges and Lowlands and 5.3% in Eastern Ridges and Lowlands. USGS gives the first a radon index of 10, in the moderate band (9 to 11), and the second 8, in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Eastern Ridges and Lowlands | Carbonate-rich glacial silt, clay. | Moderate | 10 | 93.7% |
| Eastern Ridges and Lowlands | Glacial lake deposits, clayey glacial deposits. | Low | 8 | 5.3% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Milwaukee County beside the ground around it
Wisconsin as a whole has more high-potential ground than Milwaukee County: 34.8% of its land, against 0.3% here. Every one of the 4 counties that border it has more high-potential ground, Washington County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Milwaukee County, Local resources
Radon testing and mitigation in Milwaukee County
Listed radon businesses with an address in Milwaukee County:
- Wisconsin's radon programWisconsin Department of Health ServicesWisconsin's radon program does not license radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Wisconsin.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
We recommend starting with your regional Radon Information Center since many centers provide test kits for free or reduced cost, and often with laboratory fees covered.
- Compare kits
- Professionals in Wisconsin19 professionals are listed in Wisconsin.
Listed radon professionals by town: Milwaukee
What Wisconsin's program says
- Phone
- 1-888-569-7236
- 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
Milwaukee County, Questions
Questions about radon in Milwaukee County
Are radon levels high in Milwaukee County?
In 2023, 20.2% of the radon tests reported to CDC for Milwaukee County, Wisconsin were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.5 pCi/L. Of 69 Wisconsin counties with 30 or more tests for the same period, 60 reported a higher share; pooled, the state comes to 35.7%.
Which counties border Milwaukee County?
Milwaukee County borders 4 counties: Waukesha County, Racine County, Ozaukee County and Washington County.
Products
Milwaukee County, Products
Testing a home in Milwaukee County
In Milwaukee County, 20.2% of 2,605 tests reported to CDC in 2023 reached 4 pCi/L, against 35.7% pooled across Wisconsin. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Milwaukee County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
Monitor
Hello Radon C battery radon monitor with an e-ink screen
- C-NRPP 2024/25: Not included
- Battery
- Screen
Method: Alpha spectrometry
First reading: Within 24 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Milwaukee County, Bordering counties
Counties bordering Milwaukee County
Calculated by Radon411- Radon levels in Washington CountyEPA zone 1
47.9%at or above 4 pCi/L
Median 3.8 pCi/L · 399 tests · 27.7 points above Milwaukee County
- Radon levels in Ozaukee CountyEPA zone 2
45.8%at or above 4 pCi/L
Median 3.6 pCi/L · 445 tests · 25.6 points above Milwaukee County
- Radon levels in Waukesha CountyEPA zone 1
43.2%at or above 4 pCi/L
Median 3.2 pCi/L · 1,633 tests · 23.0 points above Milwaukee County
- Radon levels in Racine CountyEPA zone 2
37.3%at or above 4 pCi/L
Median 2.7 pCi/L · 445 tests · 17.1 points above Milwaukee County
Milwaukee County, Cities and towns
Cities and towns in Milwaukee County
About 924,216 people live in Milwaukee County by the Census Bureau's estimate for July 1, 2025, 14,390 fewer than in 2020 (−1.5%). Packed into its land, that is 3,827 people per square mile. Milwaukee, the largest place on its list (562,407 residents in all), extends beyond Milwaukee County, so no share of the total is worked out for it. CDC's 2,605 reported tests for 2023 work out to 2.8 per 1,000 residents (2025 estimate), close to Wisconsin's 3.5.
From Milwaukee to River Hills, CDC publishes no figure by town: each reads Milwaukee County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Milwaukeeextends beyond Milwaukee County | 562,407 | −2.6% | Counted whole |
| West Allis | 60,119 | −0.2% | 6.5% |
| Wauwatosa | 48,649 | +0.7% | 5.3% |
| Oak Creek | 38,296 | +4.4% | 4.1% |
| Greenfield | 37,159 | −1.5% | 4.0% |
| Franklin | 36,687 | +1.5% | 4.0% |
| South Milwaukee | 20,191 | −2.8% | 2.2% |
| Cudahy | 17,655 | −2.9% | 1.9% |
| Glendale | 14,795 | +10.4% | 1.6% |
| Whitefish Bay | 14,489 | −3.0% | 1.6% |
| Greendale | 14,426 | −2.8% | 1.6% |
| Shorewood | 13,474 | −2.6% | 1.5% |
- Brown Deer
- St. Francis
- Hales Corners
- Fox Point
- Bayside (part)
- West Milwaukee
- River Hills
19 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Milwaukee County is counted whole, so it has no share.
Milwaukee County, Homes
Homes in Milwaukee County
Fewer than six in ten of Milwaukee County's 423,838 homes are detached houses (45%, against 66% across Wisconsin); the rest are attached, in shared buildings or mobile. The homes are older than Wisconsin's as a whole: half were built before 1956 (1975 for Wisconsin), and 57% date from before 1960. Most occupied homes here are rented: owners live in 50% (Wisconsin: 68%). A tenant can run a test; a fix is the landlord's to make.
| Homes | Milwaukee County | Wisconsin |
|---|---|---|
| Housing units | 423,838 | 2,750,750 |
| Detached houses | 45% | 66% |
| In buildings of 5 or more | 27% | 17% |
| Mobile homes | 1% | 3% |
| Built before 1960 | 57% | 34% |
| Built since 2000 | 9% | 20% |
| Middle year built | 1956 | 1975 |
| Owner-occupied | 50% | 68% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.