Is radon high in Madison, Wisconsin?

Low. Averaging the model's ZIP-code predictions across Madison (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 1.6 pCi/L - close to the US average of 1.8 and about 20% below the Wisconsin average of 2.0. That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Madison ranks 10 of 15 Wisconsin cities on this site.

What do actual radon tests show around Madison?

Wisconsin Department of Health Services publishes results for Dane County (not the city alone) covering 1995-2016 (5,677 tests): an average of 5.6 pCi/L, 50.9% 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 Madison is 1.6 pCi/L.

Which Madison ZIP codes have the highest radon?

Predictions for the 14 modeled ZIP codes in Madison range from 1.1 to 2.1 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 14% at or above 2. That spread is why the ZIP table below matters more than the city-wide number.

Should I test for radon in Madison?

Yes, once. The EPA recommends testing every home regardless of area. A short-term kit costs little and settles the question for your house; Madison's low predicted average describes the typical home, not yours.

What does EPA Radon Zone 1 mean for Madison?

Madison sits mainly in Dane County, which the EPA classifies as Zone 1 - highest potential (predicted average > 4 pCi/L). The zone map dates from 1993 and covers whole counties. The newer model's city average of 1.6 pCi/L does not line up with Zone 1, which is common - the EPA itself says high-radon homes exist in every zone. Neither replaces a test of your own home.

Radon levels in Madison, Wisconsin

LowEPA Zone 1

Predicted long-term basement average of 1.6 pCi/L (model estimate) across the 14 modeled ZIP codes in Madison - close to the US average of 1.8, about 20% below the Wisconsin average of 2.0. Ranked #10 of 15 Wisconsin cities on this site. Most of the city lies in Dane County.

Test Madison, WI once anyway - radon varies house to house

The predicted basement average here is 1.6 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.

Get a short-term test kit →Or track it with a continuous monitor

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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.

1.6 ± 0.10

pCi/L predicted basement mean (model SD)

1.3 ± 0.07

pCi/L predicted upstairs (above-ground) mean

1.1-2.1

range of ZIP-level basement predictions in the city

of Madison ZIPs predicted ≥ 4 pCi/L (14% ≥ 2)

Measured radon tests in Dane 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: 5.6 pCi/L
Results ≥ 4 pCi/L: 50.9%
Results ≥ 2 pCi/L: 74.5%
Sample: 5,677 tests

Figure	Model (predicted)	State tests (measured)
Mean, pCi/L	1.8 basement	5.6
Share ≥ 4 pCi/L	not a model output	50.9%

The measured mean runs 3.8 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 Madison

The typical Madison home is predicted below 2 pCi/L, the lowest band. That describes the average house; the ZIP-level predictions inside the city still span 1.1 to 2.1 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 Dane County as Zone 1 while the newer model predicts 1.6 pCi/L for Madison; where they disagree, we grade on the model but show both.

Comparable Wisconsin cities: Racine (1.7), Wauwatosa (1.4), Waukesha (1.4), Green Bay (1.9).

ZIP codes in Madison

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
53704	20%	1.5 ± 0.09	1.2	Low
53718	19%	1.5 ± 0.12	1.4	Low
53711	10%	1.7 ± 0.08	1.5	Low
53719	9%	1.1 ± 0.12	1.1	Low
53705	7%	2.2 ± 0.08	1.3	Moderate
53713	7%	1.8 ± 0.08	1.1	Low
53593	6%	1.7 ± 0.09	1.6	Low
53714	6%	1.5 ± 0.12	1.1	Low
53716	5%	2.0 ± 0.09	1.2	Moderate
53717	5%	1.8 ± 0.07	1.6	Low
53703	2%	1.4 ± 0.06	0.9	Low
53562	2%	1.6 ± 0.10	1.2	Low
53715	2%	1.6 ± 0.06	0.9	Low
53726	1%	1.6 ± 0.06	1.0	Low
53706	1%	—	—	no model
53792	<1%	—	—	no model

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.

Madison radon questions

Is radon high in Madison, Wisconsin?: Low. Averaging the model's ZIP-code predictions across Madison (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 1.6 pCi/L - close to the US average of 1.8 and about 20% below the Wisconsin average of 2.0. That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Madison ranks 10 of 15 Wisconsin cities on this site.
What do actual radon tests show around Madison?: Wisconsin Department of Health Services publishes results for Dane County (not the city alone) covering 1995-2016 (5,677 tests): an average of 5.6 pCi/L, 50.9% 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 Madison is 1.6 pCi/L.
Which Madison ZIP codes have the highest radon?: Predictions for the 14 modeled ZIP codes in Madison range from 1.1 to 2.1 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 14% at or above 2. That spread is why the ZIP table below matters more than the city-wide number.
Should I test for radon in Madison?: Yes, once. The EPA recommends testing every home regardless of area. A short-term kit costs little and settles the question for your house; Madison's low predicted average describes the typical home, not yours.
What does EPA Radon Zone 1 mean for Madison?: Madison sits mainly in Dane County, which the EPA classifies as Zone 1 - highest potential (predicted average > 4 pCi/L). The zone map dates from 1993 and covers whole counties. The newer model's city average of 1.6 pCi/L does not line up with Zone 1, 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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