How Common Is High Radon in Madison Homes?

Very common. On the Wisconsin Department of Health Services radon map, 1,231 of 2,625 tests across the 13 ZIP codes DHS lists as Madison were at or above 4 pCi/L. That's about 47%. EPA recommends fixing a home at 4 pCi/L or more. Fill out one free request below and we'll try to match you with a single NRPP or NRSB certified radon contractor working in the Madison area, who then reaches out to you.

Numbers from the Wisconsin DHS radon map (ZIP code results for tests done 1995 through 2016). Your own home's level only shows up when you test it.

Radon results by Madison ZIP code

The share of high tests changes a lot from one part of the city to another, from about a third downtown to more than 60% in 53718 on the far east side. These are the Madison ZIP codes with the most tests on the DHS map:

Public Health Madison & Dane County said in January 2026 that roughly half of the homes tested in Dane County over the past five years had high radon.

Madison's housing, from the isthmus out

Madison grew outward from the isthmus between Lake Mendota and Lake Monona, so its oldest homes sit near the Capitol and its newest on the far east and west sides. The city's 2025 to 2029 Consolidated Plan counts about one in five owner-occupied homes as built before 1950, and well over half before 1980. In Third Lake Ridge, the oldest part of the Marquette neighborhood along Williamson and Jenifer Streets, some houses go back to the 1850s, and the city's walking tour notes several resting on stone foundations. The 1920s Marquette Bungalows nearby were built on concrete. At the other end, the city's 2025 Housing Snapshot notes dozens of new single-family rental homes going up on the far east side. Newer homes are not radon-proof, so the same test applies.

What a fix usually involves here

A home with a poured or block basement floor usually gets a sub-slab system, where a fan pulls soil gas from beneath the slab and pipes it outdoors above the roofline. A split-level often has a basement under one part and a slab or crawl space under another, so the contractor may need to draw from more than one spot or seal a crawl space with a membrane. Old stone foundations near downtown can leak more air and may take extra sealing. A two-flat with one shared basement can often be covered by a single system.

Testing in Dane County

Public Health Madison & Dane County sells radon test kits by mail and at its Atrium office on South Park Street and its East Washington Avenue office, and says results usually take two to three weeks. Kits are also sold online and in hardware stores. The regional center for Dane County is listed on the DHS Radon Information Centers page.

Nearby Dane County communities

We also take requests from the rest of Dane County. On the same DHS map, Sun Prairie's 53590 ZIP shows 243 of 454 tests at or above 4 pCi/L (53.5%), Verona's 53593 shows 181 of 353 (51.2%) and Middleton's 53562 shows 202 of 403 (50.1%). Fitchburg, Monona, McFarland, Waunakee and Oregon are in the area too. Choose Dane County in the form.