Radon in Michigan: EPA zones by county, test kits and what a fix involves

Why a foundation site talks about radon

Radon is a gas that comes up out of the soil, and the way it gets into a house is through the foundation: cracks, the sump pit, the floor-wall joint, an exposed crawl space floor. The people who fix it work on the same slab and drain you may already be asking about. So it belongs here, and it belongs early, because the first step is a test, not a contractor.

EPA zones for Michigan counties

EPA’s Map of Radon Zones, built in 1993, sorts every county into one of three zones. Zone 1 predicts an average indoor screening level above 4 pCi/L. Zone 2 predicts between 2 and 4. Zone 3 predicts below 2. The county lists come from EPA’s county spreadsheet, last saved in September 2025.

Zone 1, nine counties: Branch, Calhoun, Cass, Hillsdale, Jackson, Kalamazoo, Lenawee, St. Joseph and Washtenaw. Ann Arbor and Kalamazoo are the larger cities inside them.

Zone 2, 32 counties, including Oakland, Kent, Ingham, Genesee, Livingston, Monroe, Eaton, Ionia, Lapeer, Marquette and Alpena. Troy, Grand Rapids, Lansing and Flint sit in this group.

Zone 3, 42 counties, including Wayne, Macomb, Saginaw, Muskegon, Ottawa, Berrien, St. Clair, Midland, Bay and Grand Traverse. Detroit, Warren and Sterling Heights are here.

Read those lists with EPA’s own warning in mind: the map should not be used to determine whether individual homes need to be tested, and all homes should be tested regardless of zone. EGLE says the same thing in different words. High radon readings have been found in every Michigan county, one in every four Michigan homes is expected to be above the federal action level, and the average radon level in Michigan is almost twice the average in the United States. A Zone 3 label is a county prediction. It is not a measurement of your basement.

The nine Zone 1 counties are also the nine counties where, EGLE says, the Michigan Residential Code requires radon-resistant construction in new homes. That is a rule for new construction, not for a house you already own.

What EGLE says about test kits

EGLE gives specific testing guidance.

• A short-term screening test lasts at least 48 hours, typically 2 to 7 days, and up to 90 days depending on the device.
• Closed-house conditions apply, and the winter heating season is the best time.
• Place the test in the lowest livable level. Avoid kitchens, bathrooms, laundry rooms, closets, utility rooms and crawl spaces.
• Do-it-yourself short-term kits generally cost $10 to $20, and long-term kits $20 to $50, according to EGLE’s FAQ. Kits sold by local health departments include the device, postage and lab fees, and most retail and mail-order kits include everything, though a few charge extra.
• A professional test generally costs $50 to $150 on EGLE’s FAQ and about $75 to $200 with a continuous monitor on its testing page. The two pages differ, which is why we quote the page.

EGLE recommends retesting every two years, and EPA’s guidance adds a retest after changes to the house.

The numbers that decide what you do

EPA recommends fixing a home at 4 pCi/L or higher and says to consider fixing between 2 and 4. EGLE passes on the same advice: at or above 4, install a mitigation system. EPA’s citizen’s guide, dated 2016, says radon causes about 21,000 lung cancer deaths a year, is the leading cause of lung cancer among non-smokers, and the second leading cause overall. It also says levels below 4 still pose a risk, which is why the 2 to 4 range gets a mention.

EPA says the only way to know whether you have a radon problem is to test, and symptoms will not tell you.

Sealing cracks is not the fix

Foundation cracks are the visible way in, so people reach for caulk. EGLE says sealing floor cracks alone will generally not take care of the problem. Control in an existing home needs a mitigation system that draws radon from the soil and exhausts it outdoors. EGLE says sealing may be enough only when levels are close to 4 pCi/L.

EPA describes the common methods. In homes with basements, systems pull from under the slab, from drain tile, from a sump hole or from inside block walls, and a sump can be capped to serve as the suction point. In crawl space homes, the most effective method it names is submembrane suction: covering the earth floor with high-density plastic sheeting plus a vent pipe and fan. Crawl space depressurization is, in EPA’s words, less favorable. University of Minnesota Extension, an out-of-state source, makes a related point for wet basements: an active sub-slab depressurization system with a washed-rock layer helps control radon and other soil gases, and open sumps should be sealed. Our guides on sump pumps and drainage and crawl space encapsulation and the code cover the neighboring work.

What a Michigan fix costs, with the page named

We have no Michigan contractor quotes. What we can cite is EGLE, which publishes four different ranges on four pages.

EGLE page	Michigan mitigation range
Indoor radon main page	$800 to $2,500
Radon FAQ	$750 to $1,500
Radon in real estate page	$800 to $2,000 or more
Keeping Your Home Safe from Radon brochure	$800 to $1,500

The real-estate page adds that the fan lasts around 11 years and averages about $3 a month to run. EGLE says installation takes a day or less and that a reputable contractor promises a result below 4 pCi/L. That last claim is EGLE’s, not ours, and we make no promise about any company. A passive radon-resistant system in new construction may cost $350 to $500, per the EGLE page and brochure. The radon mitigation service page carries the same rows in its cost table.

Michigan does not license radon contractors

Competitor pages often muddle this. EGLE says radon testers and mitigators are not licensed or regulated in Michigan, that it has no regulatory authority over measurement or mitigation contractors, and that it does not audit or inspect their work. Two national bodies, NRPP and NRSB, offer private certification and EGLE encourages hiring someone who holds it. We have not confirmed either body’s listings, so take that as a pointer rather than a check we ran.

EPA’s own consumer guide notes that many states require radon professionals to be licensed or registered. Michigan is not one of them. So the checks are yours: get more than one estimate and references, ask what the system will do and what it will be tested to, and ask for the post-installation test result in writing. A mitigation job can also involve electrical work for the fan and plumbing work where it touches a sump, and those trades have their own licensing, though we did not verify how a mitigation job is treated.

On permits, we found no Michigan state or city page that says whether a radon system needs a permit, with one exception: Sterling Heights lists “Radon $125.00” on its 2026-2027 plumbing permit fee chart, so a radon system is a permitted item there. Ask your city.

Buying or selling

EGLE says radon testing and mitigation are not required during a real estate transaction, and that a system can be installed before or after purchase, with the issue negotiable between buyer and seller. We could confirm that only from truncated page text, so confirm it with EGLE. The Michigan Seller Disclosure form asks about environmental hazards, radon among them.

Where to go next

Test, then read the number against 2 and 4. If the number is high and the house also has a wet basement or cracks, start with foundation cracks and sump pump questions together, because one contractor visit can cover both. Before you sign, read how to check a Michigan builder license, keeping in mind that it does not apply to the radon part of the work.