Eau Claire County Is Radon Country: What Your Number Probably Is
If you own a home in Eau Claire County, Wisconsin, there's a real chance the air in your basement carries more radon than the EPA is comfortable with — and you'd never know without a test, because radon has no color, no smell, and no taste. This isn't a scare pitch. It's just where the county sits on the map.
Wisconsin as a whole is a high-radon state. The state Department of Health Services estimates about 1 in 10 Wisconsin homes has an elevated radon level, and much of the western and central part of the state — Eau Claire County included — runs hotter than that average. The EPA's radon zone map puts a big chunk of this region in Zone 1, the highest-risk category, meaning the predicted average indoor level is at or above the 4.0 pCi/L action level.
Why this corner of Wisconsin runs high
Radon comes from the natural breakdown of uranium in soil and rock. It seeps up through the ground and gets pulled into houses through cracks in the foundation, gaps around pipes, sump pits, and slab joints, where it builds up in the lowest levels of the home. The glacial soils and underlying bedrock across much of western Wisconsin are naturally uranium-bearing, and the cold-climate building style here — tight, heated homes with basements that run under negative pressure in winter — is practically designed to draw that soil gas indoors.
What the number actually means
Radon is measured in picocuries per liter of air (pCi/L). The EPA sets the action level at 4.0 pCi/L — at or above that, you should fix it. But the risk doesn't magically start at 4.0; it's a sliding scale, and the EPA notes there's no truly safe level. They suggest considering a fix even between 2.0 and 4.0. For context, the average outdoor level is about 0.4 pCi/L, and the average indoor level in the U.S. is around 1.3. In Zone 1 counties like Eau Claire, it's common to see basement tests come back at 4, 6, 8, or higher.
Radon is the second leading cause of lung cancer overall and the number one cause among people who've never smoked — an estimated 21,000 deaths a year in the U.S. And if you do smoke or vape, living with high radon multiplies your lung cancer risk by roughly ten times. That combination is the dangerous one.
Testing: cheap, easy, and the only thing that matters
You cannot guess your radon level from your neighbor's, your home's age, or whether the basement feels damp. Testing is the whole game, and it's cheap. A short-term test kit runs $10–$30 at a hardware store or online, and Wisconsin's regional Radon Information Centers often provide kits free or at reduced cost — you can reach one at 1-888-LOW-RADON. Winter is the best time to test in Wisconsin: the house is closed up and running under the negative pressure that pulls the most radon in, so you catch it at its worst-case.
- Put the test in the lowest level you regularly use — a finished basement or a first floor over a slab.
- Keep windows and doors closed as much as possible during a short-term test (2–7 days).
- If a short-term test comes back elevated, confirm with a second test or a longer-term (90+ day) kit before spending on mitigation.
If your number is high
A high result is a fixable problem, not a reason to panic or move. A radon mitigation system is, at its core, a sealed pipe and a quiet fan: it draws the radon-laden soil gas from under your foundation and vents it above the roofline before it ever gets into your living space. In a typical Eau Claire County home, a properly installed sub-slab depressurization system routinely knocks a level from the high single digits down under 2.0 pCi/L. It runs on about the same electricity as a light bulb and mostly you forget it's there.
Joe — the septic-ignoring, well-neglecting legend himself — finished his Eau Claire basement into a nice little rec room, put the kids' setup and a treadmill down there, and spent every winter evening in it for years. Never tested. When he finally went to sell, the buyer's inspector ran a radon test and it came back at 7.8. Joe had been marinating in Zone-1 basement air the whole time, and the fix that would've cost him a modest afternoon's install turned into a rushed, price-doesn't-matter scramble to close the deal. Test first, live easy.
Eau Claire County homeowners have a genuine head start here: the region is well-mapped, the testing is cheap, and the fix is routine. If you'd rather have a certified local outfit handle the test-and-mitigate end to end, the folks at Eau Claire Radon do exactly this work in the county day in and day out. Whether you test it yourself or bring someone in, the one thing not to do is nothing — because in this county, "probably fine" and "actually tested" are two very different bets.