One in Four Michigan Homes Is Over the Radon Line
You cannot see it, smell it or taste it, and Michigan has roughly three times the national share of homes above the EPA action level. A test kit costs less than dinner out. Here is what the state's own numbers show.
Radon is a naturally occurring radioactive gas produced by the decay of uranium in soil. It moves through porous ground, finds the openings between the soil and your house, and accumulates indoors. Long-term exposure raises lung cancer risk — it is the second leading cause of lung cancer nationally.
Per Michigan EGLE: about one in four Michigan homes is projected to exceed 4 pCi/L, and elevated results have been found in all 83 counties. The state average is nearly double the U.S. average — a function of our geology and the fact that Michigan homes are closed up most of the year.
The number to know: 4 pCi/L
The EPA's action level is 4 picocuries per liter of air. At or above it, fix the home. Between 2 and 4, the EPA says consider fixing. There is no threshold below which radon is beneficial — lower is better, and mitigation systems routinely bring homes well under the line.
EGLE recommends retesting every two years even in a home that already has a mitigation system, because houses settle, new cracks open in the foundation, and levels change.
Our service area, by county
EGLE publishes the share of tests at or above 4 pCi/L by county. In the counties we work in every day:
Those are county averages of self-selected tests, and EGLE is explicit that the map cannot tell you whether your own home needs testing. Two houses on the same street can read very differently. Every home should be tested.
How radon and water share the same doors
This is why a waterproofing company writes about radon. The pathways are the same ones we deal with all week: cracks in the slab and walls, the cold joint where floor meets wall, utility penetrations, an open sump basin, and bare soil in a crawl space. Whatever route groundwater takes into your basement is a route soil gas can take too.
The overlap has a practical consequence. If you are already opening the floor for a drain tile system, that is the moment to rough in radon control — sealed sump lid, sub-slab suction point, stack routed and vented. Doing it during waterproofing costs a fraction of retrofitting later.
What mitigation actually is
A sub-slab depressurization system: a suction point cut into the slab, a sealed pipe run up and out of the house, and an inline fan that pulls soil gas from beneath the foundation and vents it above the roofline before it can enter the living space. Slab and sump openings are sealed so the system draws from the soil, not from your basement air. As EGLE puts it, the system grabs the radon before it ever enters the home.
- Test first. Short-term kits are inexpensive; place one in the lowest lived-in level, follow the closed-house instructions.
- Confirm a high result. EGLE advises a follow-up test before acting on a reading above 4 pCi/L.
- Mitigate, then re-test. A post-installation test is how you know the system is doing its job.
- Re-test every two years, system or not.
One more reason not to wait: radon comes up in real estate transactions constantly, and a documented mitigation system is a selling point rather than a negotiation problem. It is a health fix that happens to protect your resale position too.
Sources
- Michigan EGLE, 25% of Michigan homes have elevated levels of radon (January 2026) — 25% vs. 7% nationally, elevated results in all 83 counties, retest every two years.
- Michigan EGLE, Percentage of Elevated Radon Test Results by County — county-level test percentages, including Livingston, Oakland, Genesee, Wayne and Macomb.
- Michigan EGLE, Michigan Indoor Radon Program — confirmatory testing, mitigation guidance, and why levels change as homes settle.
- U.S. EPA, EPA Map of Radon Zones — fix at 4 pCi/L or higher, consider fixing between 2 and 4, and test regardless of zone.
