Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Locations and reports
Radon Levels in Door County, Wisconsin
EPA puts Door County in Zone 1, its highest radon zone, and high results are common there: 42.3% of the 156 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
42.3%
6.6 pts above WI
- Door
- 42.3%
- Wisconsin
- 35.7%
156 tests, 2023
Median result
3.0pCi/L
Below action level
- Door
- 3.0 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2023
Tests reported
156
35th of 69 by tests
- Door
- 156
- Dane
- 2,887
Reported to CDC before any fix, 2023
EPA radon zone
Zone 1
Highest potential
- Zone 1
- 2
- 3
1 highest, 3 lowest
EPA predicts over 4 pCi/L indoors
Rank in Wisconsin
26 of 69
Middle half
- Door
- 42.3%
- Langlade
- 65.8%
By share, of 69 with 30+ tests
Read a result for Door County
Starts at Door County's median, 3.0 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 3.0 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. Door County's median reported result, 2023.
The data
Door County, At a glance
Door County at a glance
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA puts all of Door County in
USGS geologic potential: High across 90% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Door County, 2023
| Year | Share of reported tests at or above 4 pCi/L |
|---|---|
| 2014 | 55.1% |
| 2015 | 48.8% |
| 2016 | 30.2% |
| 2017 | 40.4% |
| 2019 | 43.7% |
| 2020 | 25.7% |
| 2021 | 31.8% |
| 2022 | 45.5% |
| 2023 | 42.3% |
2023: 42.3%. Across these years the share ran from 25.7% to 55.1%. Each column counts radon tests reported to CDC that year, not homes.
What these figures count
These are the 156 tests reported to CDC for Door 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).
Door County, Compared
Door County radon figures, compared
Calculated by Radon411In Door County, about 4 in 10 reported tests in 2023 (66 of 156) were at or above EPA's action level. Against the national pool of 33.4%, the gap is 8.9 points higher. Across 72 Wisconsin counties pooled together, 35.7% of tests reached that level, so Door County runs 6.6 points above its state.
Kewaunee County, the one bordering county with a figure for the same period, reported 44.6%. By share, Door County is 26th of 69 Wisconsin counties with 30 or more tests for the same period.
Year by year, 2014 opened at 55.1% and 2023 closed at 42.3% (down 12.8 points), with 2014 the high at 55.1%. Half the tests came in under 3.0 pCi/L and half over it; the single highest reached 78.5 pCi/L. Below the action level, 56 tests (35.9%) came in under 2 pCi/L, against 41.4% statewide, and 34 tests (21.8%) fell between 2 and 4, against 23.0% statewide.
Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 42.3% share point the same way here. USGS geology rates 90% of the county's land high radon potential. CDC also counts 5 tests taken after mitigation in Door County for the same period: tests in homes where a fix was already in.
The busiest year on file was 2020, with 342 tests reported; the quietest, 2023, had 156.
Door CountyWisconsin, pooled
| Year | Tests | Door County, at or above 4 pCi/L | Wisconsin, pooled |
|---|---|---|---|
| 2014 | 156 | 55.1% | 51.1% |
| 2015 | 326 | 48.8% | 51.6% |
| 2016 | 192 | 30.2% | 45.2% |
| 2017 | 267 | 40.4% | 44.8% |
| 2019 | 309 | 43.7% | 42.9% |
| 2020 | 342 | 25.7% | 27.0% |
| 2021 | 201 | 31.8% | 39.9% |
| 2022 | 178 | 45.5% | 42.9% |
| 2023 | 156 | 42.3% | 35.7% |
Pooled shares: Radon411's sum of CDC's county counts for one period.
Door County, Geology
The ground under Door County
PredictedMost of the ground under Door County is one class on USGS's geologic map: 89.6% of its land is high radon potential, with 3.3% moderate and 1.6% low. The map puts 89.6% of Door County in the area it calls Eastern Ridges and Lowlands and 3.3% in Green Bay Lobe, with one smaller area beside them. USGS gives the first a radon index of 12, in the high band (12 to 17), and the second 10, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Eastern Ridges and Lowlands | Glacial deposits derived from Ordovician carbonate rocks. | High | 12 | 89.6% |
| Green Bay Lobe | Glacial deposits derived from carbonate and igneous rocks. | Moderate | 10 | 3.3% |
| Eastern Ridges and Lowlands | Glacial lake deposits, clayey glacial deposits. | Low | 8 | 1.6% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Door County beside the ground around it
Door County has more high-potential ground than Wisconsin as a whole: 89.6% of its land against 34.8%. Of the one county that borders it, none has as large a share of high-potential ground; Kewaunee County comes nearest at 12.1%.
The map rates the ground, not the air in any home.
Local help
Door County, Local resources
Radon testing and mitigation in Door 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
Door County, Questions
Questions about radon in Door County
Are radon levels high in Door County?
In 2023, 42.3% of the radon tests reported to CDC for Door County, Wisconsin were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.0 pCi/L. Of 69 Wisconsin counties with 30 or more tests for the same period, 25 reported a higher share; pooled, the state comes to 35.7%.
Which counties border Door County?
Door County borders 1 county: Kewaunee County.
Products
Door County, Products
Testing a home in Door County
In Door County, 42.3% of 156 tests reported to CDC in 2023 reached 4 pCi/L, against 35.7% pooled across Wisconsin. In Zone 1 the year-round level in Door County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.
Test kits and monitors3
See every kit and monitor
MonitorAEGTEST
HOUND-3699 radon monitor with a 2.1-inch touchscreen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
First reading: Within 1 hour
Short-term kitempowerDX
Standard Radon Test short-term mail-in radon test kit
- Lab fee included
Method: Passive sampler
In home: 48 to 96 hours
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Door County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Door County
Explore
Door County, Bordering counties
Counties bordering Door County
Calculated by Radon411- Radon levels in Kewaunee CountyEPA zone 2
44.6%at or above 4 pCi/L
Median 3.7 pCi/L · 56 tests · 2.3 points above Door County
Door County, Cities and towns
Cities and towns in Door County
The Census Bureau estimates 30,616 residents in Door County for July 1, 2025, 488 more than in 2020 (+1.6%). That works out to 64 people per square mile of land. Its largest town, Sturgeon Bay, has 9,917 residents, 32.4% of the total. Together its 5 incorporated places hold 40.2% of those residents; the other 59.8% live outside any of them. CDC's 156 reported tests for 2023 work out to 5.1 per 1,000 residents (2025 estimate), close to Wisconsin's 3.5.
From Sturgeon Bay to Ephraim, CDC publishes no figure by town: each reads Door County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Sturgeon Bay | 9,917 | +2.6% | 32.4% |
| Sister Bay | 1,177 | +1.5% | 3.8% |
| Forestville | 460 | −4.0% | 1.5% |
| Egg Harbor | 395 | +9.7% | 1.3% |
| Ephraim | 348 | +0.9% | 1.1% |
5 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).
Door County, Homes
Homes in Door County
Of Door County's 23,996 homes, 75% are detached houses, against 66% across Wisconsin; 11% are in buildings of five or more homes. Half of its homes were built before 1982, close to Wisconsin's 1975: 27% date from before 1960 and 25% from 2000 or later. Owners live in 79% of the occupied homes (Wisconsin: 68%), so for most households a test and a fix are their own to order.
| Homes | Door County | Wisconsin |
|---|---|---|
| Housing units | 23,996 | 2,750,750 |
| Detached houses | 75% | 66% |
| In buildings of 5 or more | 11% | 17% |
| Mobile homes | 6% | 3% |
| Built before 1960 | 27% | 34% |
| Built since 2000 | 25% | 20% |
| Middle year built | 1982 | 1975 |
| Owner-occupied | 79% | 68% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.