Short-term kitKidde
442020 short-term charcoal radon test kit
- Lab fee included
Method: Charcoal
In home: 3 days
Locations and reports
Radon Levels in Ozaukee County, Wisconsin
EPA puts Ozaukee County in Zone 2, its middle radon zone, and high results are common there: 45.8% of the 445 radon tests reported to CDC (2023) came back 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
45.8%
10.1 pts above WI
- Ozaukee
- 45.8%
- Wisconsin
- 35.7%
445 tests, 2023
Median result
3.6pCi/L
Below action level
- Ozaukee
- 3.6 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
445
10th of 69 by tests
- Ozaukee
- 445
- 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
16 of 69
Top quarter
- Ozaukee
- 45.8%
- Langlade
- 65.8%
By share, of 69 with 30+ tests
Read a result for Ozaukee County
Starts at Ozaukee County's median, 3.6 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 3.6 pCi/L
Between 2 and 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Ozaukee County's median reported result, 2023.
The data
Ozaukee County, At a glance
Ozaukee County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Ozaukee County is a
USGS geologic potential: Low across 51% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Ozaukee County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 53.6% |
| 2015 | 50.4% |
| 2016 | 37.9% |
| 2017 | 41.8% |
| 2019 | 32.1% |
| 2020 | 36.5% |
| 2021 | 34.2% |
| 2022 | 40.1% |
| 2023 | 45.8% |
2023: 45.8%. Across these years the share ran from 32.1% to 53.6%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 445 tests reported to CDC for Ozaukee 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).
Ozaukee County, Compared
Ozaukee County radon figures, compared
Calculated by Radon411In Ozaukee County, about 5 in 10 reported tests in 2023 (204 of 445) were at or above EPA's action level. Against the national pool of 33.4%, the gap is 12.4 points higher. Across 72 Wisconsin counties pooled together, 35.7% of tests reached that level, so Ozaukee County runs 10.1 points above its state.
Of 4 neighbours with a figure, 1 reported a larger share at or above 4 pCi/L and 3 a smaller one; the spread is 20.2% (Milwaukee County) to 47.9% (Washington County). By share, Ozaukee County is 16th of 69 Wisconsin counties with 30 or more tests for the same period.
Year by year, 2014 opened at 53.6% and 2023 closed at 45.8% (down 7.8 points), with 2014 the high at 53.6%. Half the tests came in under 3.6 pCi/L and half over it; the single highest reached 49.8 pCi/L. Below the action level, 138 tests (31.0%) came in under 2 pCi/L, against 41.4% statewide, and 103 tests (23.1%) fell between 2 and 4, against 23.0% statewide.
Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 45.8% share point the same way here. USGS geology rates 51% of the county's land low radon potential. CDC also counts 31 tests taken after mitigation in Ozaukee County for the same period: tests in homes where a fix was already in.
The busiest year on file was 2015, with 685 tests reported; the quietest, 2020, had 271.
Ozaukee CountyWisconsin, pooled
45.8% % of tests35.7% % of tests
| Year | Tests | Ozaukee County, at or above 4 pCi/L | Wisconsin, pooled |
|---|---|---|---|
| 2014 | 330 | 53.6% | 51.1% |
| 2015 | 685 | 50.4% | 51.6% |
| 2016 | 475 | 37.9% | 45.2% |
| 2017 | 512 | 41.8% | 44.8% |
| 2019 | 552 | 32.1% | 42.9% |
| 2020 | 271 | 36.5% | 27.0% |
| 2021 | 330 | 34.2% | 39.9% |
| 2022 | 352 | 40.1% | 42.9% |
| 2023 | 445 | 45.8% | 35.7% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Ozaukee County, Geology
The ground under Ozaukee County
PredictedUSGS's geologic map splits Ozaukee County: 51.0% of its land is low radon potential and 29.5% high and 19.3% moderate. The map puts 51.0% of Ozaukee County in the area it calls Eastern Ridges and Lowlands and 29.5% in Eastern Ridges and Lowlands, with one smaller area beside them. USGS gives the first a radon index of 8, in the low band (5 to 8), and the second 12, in the high band (12 to 17).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Eastern Ridges and Lowlands | Glacial lake deposits, clayey glacial deposits. | Low | 8 | 51.0% |
| Eastern Ridges and Lowlands | Glacial deposits derived from Ordovician carbonate rocks. | High | 12 | 29.5% |
| Eastern Ridges and Lowlands | Carbonate-rich glacial silt, clay. | Moderate | 10 | 19.3% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Ozaukee County beside the ground around it
On high-potential ground Ozaukee County is close to Wisconsin as a whole: 29.5% of its land against 34.8%. Of the 4 counties that border it, 3 have more high-potential ground, Washington County the most at 100%.
The map rates the ground, not the air in any home.
Local help
Ozaukee County, Local resources
Radon testing and mitigation in Ozaukee 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.
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
Ozaukee County, Questions
Questions about radon in Ozaukee County
Are radon levels high in Ozaukee County?
In 2023, 45.8% of the radon tests reported to CDC for Ozaukee County, Wisconsin were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.6 pCi/L. Of 69 Wisconsin counties with 30 or more tests for the same period, 15 reported a higher share; pooled, the state comes to 35.7%.
Which counties border Ozaukee County?
Ozaukee County borders 4 counties: Washington County, Milwaukee County, Sheboygan County and Waukesha County.
Products
Ozaukee County, Products
Testing a home in Ozaukee County
In Ozaukee County, 45.8% of 445 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 Ozaukee 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
View Radon Wi-Fi radon monitor with an e-paper display
- C-NRPP 2024/25: Approved
- Battery
- Wi-Fi, Bluetooth
- Screen, app
Method: Alpha spectrometry
Readings: Every 60 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Ozaukee County, Bordering counties
Counties bordering Ozaukee 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 · 2.1 points above Ozaukee County
- Radon levels in Waukesha CountyEPA zone 1
43.2%at or above 4 pCi/L
Median 3.2 pCi/L · 1,633 tests · 2.6 points below Ozaukee County
- Radon levels in Sheboygan CountyEPA zone 2
42.9%at or above 4 pCi/L
Median 3.3 pCi/L · 399 tests · 2.9 points below Ozaukee County
- Radon levels in Milwaukee CountyEPA zone 2
20.2%at or above 4 pCi/L
Median 1.5 pCi/L · 2,605 tests · 25.6 points below Ozaukee County
Ozaukee County, Cities and towns
Cities and towns in Ozaukee County
The Census Bureau estimates 94,346 residents in Ozaukee County for July 1, 2025, 2,715 more than in 2020 (+3.0%). That works out to 405 people per square mile of land. Its largest town, Mequon, has 25,120 residents, 26.6% of the total. CDC's 445 reported tests for 2023 work out to 4.7 per 1,000 residents (2025 estimate), close to Wisconsin's 3.5.
From Mequon to Newburg, CDC publishes no figure by town: each reads Ozaukee County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Mequon | 25,120 | −0.1% | 26.6% |
| Grafton | 13,389 | +10.9% | 14.2% |
| Cedarburg | 12,916 | +5.9% | 13.7% |
| Port Washington | 12,658 | +1.8% | 13.4% |
| Saukville | 4,554 | +7.1% | 4.8% |
| Baysideextends beyond Ozaukee County | 4,331 | −2.8% | Counted whole |
| Thiensville | 3,267 | −0.6% | 3.5% |
| Belgium | 2,540 | +4.2% | 2.7% |
| Fredonia | 2,252 | −0.9% | 2.4% |
| Newburgextends beyond Ozaukee County | 1,129 | −0.6% | Counted whole |
10 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Ozaukee County is counted whole, so it has no share.
Ozaukee County, Homes
Homes in Ozaukee County
Of Ozaukee County's 39,415 homes, 66% are detached houses, against 66% across Wisconsin; 18% are in buildings of five or more homes. Half of its homes were built before 1977, close to Wisconsin's 1975: 26% date from before 1960 and 21% from 2000 or later. 73% of occupied homes are lived in by their owner (Wisconsin: 68%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Ozaukee County | Wisconsin |
|---|---|---|
| Housing units | 39,415 | 2,750,750 |
| Detached houses | 66% | 66% |
| In buildings of 5 or more | 18% | 17% |
| Mobile homes | under 1% | 3% |
| Built before 1960 | 26% | 34% |
| Built since 2000 | 21% | 20% |
| Middle year built | 1977 | 1975 |
| Owner-occupied | 73% | 68% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.