Locations and reports
Radon in Oshkosh, Wisconsin
EPA puts Winnebago County, where Oshkosh is, in Zone 2, its middle radon zone, and high results are common there: 42.4% of the 512 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
42.4%
6.7 pts above WI
- Winnebago
- 42.4%
- Wisconsin
- 35.7%
Winnebago, 25th of 69 in WI, 2023
Median result
3.1pCi/L
Below action level
- Winnebago
- 3.1 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of Winnebago's tests, 2023
Nearest county
51.6%
Calumet, 18 miles
- Calumet
- 51.6%
- Winnebago
- 42.4%
122 tests, 2023
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
Winnebago, where Oshkosh is
Tests reported
512
In Winnebago
- Winnebago
- 512
- Calumet
- 122
Reported to CDC before any fix, 2023
Read a result for Oshkosh
Starts at Winnebago County's median, 3.1 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 3.1 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. Winnebago County's median reported result, 2023.
The data
Oshkosh, What is published
What is published for Oshkosh
Every figure for Oshkosh is a county's
Radon data is published by county, not by city, so for Oshkosh it is Winnebago County's: its EPA zone (Zone 2) and the 512 tests reported to CDC for 2023. Only a test tells you about one home.
Oshkosh covers 27 square miles of land, all of it in Winnebago County. About 67,460 people live there, 2,497 to the square mile.
Oshkosh, Counties
The county Oshkosh lies in
MeasuredWinnebago County's EPA zone and the figures CDC publishes for it, 2023.
Winnebago CountyZone 2Moderate predicted potential
- 42.4%
- Reported tests at or above 4 pCi/L
- 3.1 pCi/L
- Median reported result
- 512 tests
- Tests reported to CDC
- 9
- Annual years on file
Winnebago County ranks 25th of 69 Wisconsin counties with 30 or more tests for that period, 6.7 points above the 35.7% pooled across Wisconsin's counties, 9.0 points above the national pool of 33.4%.
Measured from the middle of Oshkosh, the nearest counties with a CDC figure for 2023 are Calumet County (18 miles, 51.6% of 122 tests), Fond du Lac County (19 miles, 19.6% of 984 tests) and Outagamie County (28 miles, 40.7% of 337 tests). Across the 8 nearest, the share at or above 4 pCi/L runs from 19.6% to 52.8%; the farthest of them, Manitowoc County, is 38 miles away at 31.1%.
No business in the directory gives Oshkosh as its address; the Wisconsin list covers it. Wisconsin's other cities with a page of their own: Madison, Appleton, Green Bay and Wausau.
The counties around Oshkosh
By distance from the middle of Oshkosh; counties with 30 or more tests.
Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2023.
Oshkosh, Geology
The ground under Oshkosh
PredictedUSGS's geologic map puts all of Oshkosh's mapped land in one class: moderate radon potential. All of it lies in the area the map calls Green Bay Lobe, to which USGS gives a radon index of 10, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Green Bay Lobe | Glacial deposits derived from carbonate and igneous rocks. | Moderate | 10 | 99.6% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Oshkosh beside its county and Wisconsin
Winnebago County as a whole has 18.5% of its land rated high; none of that ground lies under Oshkosh. Across Wisconsin 34.8% of the land is rated high; none of Oshkosh's is.
The map rates the ground, not the air in any home.
Oshkosh, Homes
Homes in Oshkosh
Of Oshkosh's 29,156 homes, 55% are detached houses, against 66% across Winnebago County; 25% are in buildings of five or more homes. Half of its homes were built before 1972, close to Winnebago County's 1975: 41% date from before 1960 and 16% from 2000 or later. 54% of occupied homes are lived in by their owner (Winnebago County: 66%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Oshkosh | Winnebago County | Wisconsin |
|---|---|---|---|
| Housing units | 29,156 | 76,770 | 2,750,750 |
| Detached houses | 55% | 66% | 66% |
| In buildings of 5 or more | 25% | 19% | 17% |
| Mobile homes | 1% | 2% | 3% |
| Built before 1960 | 41% | 34% | 34% |
| Built since 2000 | 16% | 18% | 20% |
| Middle year built | 1972 | 1975 | 1975 |
| Owner-occupied | 54% | 66% | 68% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.
Local help
Oshkosh, Local resources
Local resources for Oshkosh
Who to ask in Wisconsin: its radon program, test kits and professionals.
- Wisconsin's radon programWisconsin Department of Health Services, phone 1-888-569-7236.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 WisconsinRadon testers and mitigators in Wisconsin, each with how its listing was checked.
The program's own words on licensing are on the Wisconsin page.
What it means
Oshkosh, Questions
Questions about radon in Oshkosh
What radon zone is Oshkosh in?
EPA's map puts Winnebago County, and with it Oshkosh, in Zone 2, the map's middle class: a predicted county average of 2 to 4 pCi/L.
What are radon levels in Oshkosh?
High results are ordinary around Oshkosh: 42.4% of the 512 tests reported from Winnebago County for 2023 were at or above 4 pCi/L, the level at which EPA says to fix a home. The median reported result was 3.1 pCi/L.
Should I test my home in Oshkosh?
Yes. Winnebago County reported about 217 of its 512 tests at or above 4 pCi/L. That is above Wisconsin's pooled 35.7%, and ranks Winnebago County 25th of the 69 Wisconsin counties with 30 or more tests. Which homes they were, no map can say. How to test a home.
What ground is Oshkosh built on, as far as radon goes?
USGS's geologic map puts all of Oshkosh on one named area, "Green Bay Lobe", rated moderate for radon potential, radon index 10.
Is radon higher in the counties around Oshkosh?
It depends which way you go. 3 of the 8 nearest counties with a figure report a larger share than Winnebago County's 42.4% and 5 a smaller one: from Fond du Lac County (19.6%, 19 miles off) to Waupaca County (52.8%, 37 miles off).
The answers use the published figures of Winnebago County, the county Oshkosh lies in.
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