Blog · Metro Detroit
Short answer: yes — more than most people expect. Here's what the data actually says, what it means for a home you're buying in Metro Detroit, and how testing fits into the process.
Radon doesn't get the attention that a leaking roof or a cracked foundation does, because you can't see it, smell it, or feel it. But it's worth understanding before you buy a home in Michigan — because the state has more radon than most people assume, and the only way to know whether a specific house has a problem is to test it.
Radon is a naturally occurring radioactive gas. It forms as uranium in soil and rock breaks down over time, and it seeps upward through the ground. Outdoors, it disperses harmlessly into the air. Indoors, it can collect — entering through foundation cracks, sump pits, crawl spaces, and gaps around pipes, then accumulating in the lowest levels of the home. Long-term exposure to elevated levels is recognized by the EPA as a leading cause of lung cancer, second only to smoking.
Michigan's glacial soils and underlying geology produce radon across the entire state — public health data shows elevated levels have been documented in all 83 counties, and statewide roughly one in four homes is projected to test above the EPA's action level of 4 picocuries per liter (pCi/L). That's not a fringe risk; it's a one-in-four coin flip on any given house.
Metro Detroit sits in the moderate range overall, but "moderate average" is misleading when you're buying one specific home. Radon levels depend on the soil directly beneath that house, how the foundation was built, and how the home breathes — so two houses on the same street can test very differently. The county average tells you nothing reliable about the basement you're about to own.
The EPA's action level is 4 pCi/L. At or above that, the recommendation is to install a mitigation system. Below it, the gas is still present — there's no level considered completely risk-free — but mitigation generally isn't called for. A test gives you a concrete number to work with rather than a guess, and during a real estate transaction that number can become a point of negotiation.
A standard real estate radon test uses a continuous monitor placed in the lowest livable level of the home for a set measurement period — typically around 48 hours — under "closed-house" conditions, meaning windows and exterior doors stay shut except for normal entry and exit. The monitor records hourly readings and produces an averaged result, which is more tamper-resistant and more informative than a single passive charcoal kit. It's an inexpensive add-on to a standard inspection, and the results come back quickly enough to fit inside a normal inspection timeline.
A high result is not a reason to walk away from a house. Radon is one of the more straightforward problems to fix. A mitigation system — usually a sub-slab depressurization setup that vents soil gas safely above the roofline — typically runs somewhere in the range of $800 to $2,000 installed, depending on the home. Buyers frequently negotiate for the seller to install one, or for a credit to cover it. After mitigation, a follow-up test confirms the levels have dropped.
Radon is common enough in Michigan that testing during a home purchase is a reasonable, low-cost step rather than an overreaction. It's also worth retesting every couple of years even after you move in, because foundations settle, new cracks form, and levels change over time. If you'd like radon testing included with your inspection, Gio offers it as an add-on — see the radon testing page for details, or call (586) 822-9912.
This article is general information, not medical or environmental advice. For statewide radon data and free test kit availability, the Michigan Department of Environment, Great Lakes, and Energy (EGLE) maintains a public radon program.