Radon levels in Green Bay, Wisconsin
LowEPA Zone 2Predicted long-term basement average of 1.9 pCi/L (model estimate) across the 7 modeled ZIP codes in Green Bay - close to the US average of 1.8, close to the Wisconsin average of 2.0. Ranked #8 of 15 Wisconsin cities on this site. Most of the city lies in Brown County.
Test Green Bay, WI once anyway - radon varies house to house
The predicted basement average here is 1.9 pCi/L, below the EPA's 2 pCi/L "consider fixing" threshold. That's good news for the area - but the EPA still recommends every home be tested, because foundation cracks, soil pockets and ventilation make one house very different from its neighbor. One inexpensive kit settles it.
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Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. Measured state test results are shown separately below, labeled with their source and years. How the numbers work.
1.9 ± 0.09
pCi/L predicted basement mean (model SD)
1.1 ± 0.07
pCi/L predicted upstairs (above-ground) mean
1.6-2.2
range of ZIP-level basement predictions in the city
0%
of Green Bay ZIPs predicted ≥ 4 pCi/L (43% ≥ 2)
Measured radon tests in Brown County (Wisconsin Department of Health Services, 1995-2016)
Actual results from home radon tests reported to the state, separate from the model estimate above. Coverage: 1995-2016.
- Measured mean
- 5.2 pCi/L
- Results ≥ 4 pCi/L
- 51.7%
- Results ≥ 2 pCi/L
- 74.4%
- Sample
- 2,723 tests
| Figure | Model (predicted) | State tests (measured) |
|---|---|---|
| Mean, pCi/L | 2.0 basement | 5.2 |
| Share ≥ 4 pCi/L | not a model output | 51.7% |
The measured mean runs 3.2 pCi/L above the model because state test data is voluntary and skews toward basements, winter, and homeowners who already suspected a problem, while the model estimates the long-term average across all homes.
Source: Wisconsin Indoor Radon Test Results (Wisconsin Radon Map Service, layer 3), Wisconsin Department of Health Services. No license statement on the public feature service. Method and download.
What this means for Green Bay
The typical Green Bay home is predicted below 2 pCi/L, the lowest band. That describes the average house; the ZIP-level predictions inside the city still span 1.6 to 2.2 pCi/L.
The city figure is not a separate estimate: it is the mean of the model's ZIP-code predictions, weighted by the share of the city's land in each ZIP (Census 2020 ZCTA-to-place relationship file). Note that the EPA classifies Brown County as Zone 2 while the newer model predicts 1.9 pCi/L for Green Bay; where they disagree, we grade on the model but show both.
Comparable Wisconsin cities: Kenosha (2.0), La Crosse (2.1), Racine (1.7), Madison (1.6).
ZIP codes in Green Bay
ZIPs that overlap the city, largest share of its land first. Predicted basement and upstairs means are model estimates; ZIPs the model does not cover show a dash.
| ZIP | Share of city | Basement | Upstairs | Grade |
|---|---|---|---|---|
| 54311 | 34% | 1.9 ± 0.12 | 1.2 | Low |
| 54302 | 19% | 1.9 ± 0.07 | 0.9 | Low |
| 54303 | 17% | 2.2 ± 0.09 | 1.1 | Moderate |
| 54304 | 13% | 2.0 ± 0.06 | 1.1 | Low |
| 54313 | 9% | 1.6 ± 0.09 | 1.1 | Low |
| 54229 | 5% | 2.1 ± 0.06 | 1.3 | Moderate |
| 54301 | 5% | 2.2 ± 0.07 | 1.1 | Moderate |
Testing help in Wisconsin
Wisconsin's radon program page is at www.dhs.wisconsin.gov; it lists testing and certified-mitigator guidance. EPA state radon contacts page. If a test comes back at 4 pCi/L or higher, mitigation typically costs $800-$2,500 installed; use EPA find-a-professional and read the mitigation guide.
Green Bay radon questions
- Is radon high in Green Bay, Wisconsin?
- Low. Averaging the model's ZIP-code predictions across Green Bay (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 1.9 pCi/L - close to the US average of 1.8 and close to the Wisconsin average of 2.0. That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Green Bay ranks 8 of 15 Wisconsin cities on this site.
- What do actual radon tests show around Green Bay?
- Wisconsin Department of Health Services publishes results for Brown County (not the city alone) covering 1995-2016 (2,723 tests): an average of 5.2 pCi/L, 51.7% of results at or above the 4 pCi/L action level. These are voluntary home tests, so they skew toward basements and toward homes where radon was suspected; the model's predicted basement average for Green Bay is 1.9 pCi/L.
- Which Green Bay ZIP codes have the highest radon?
- Predictions for the 7 modeled ZIP codes in Green Bay range from 1.6 to 2.2 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 43% at or above 2. The city is fairly uniform, so the city-wide number is a reasonable guide for any neighborhood.
- Should I test for radon in Green Bay?
- Yes, once. The EPA recommends testing every home regardless of area. A short-term kit costs little and settles the question for your house; Green Bay's low predicted average describes the typical home, not yours.
- What does EPA Radon Zone 2 mean for Green Bay?
- Green Bay sits mainly in Brown County, which the EPA classifies as Zone 2 - moderate potential (2-4 pCi/L). The zone map dates from 1993 and covers whole counties. The newer model's city average of 1.9 pCi/L does not line up with Zone 2, which is common - the EPA itself says high-radon homes exist in every zone. Neither replaces a test of your own home.
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