Radon in Minnesota homes: testing, fixing, and your rights when buying or selling

Why Minnesota, specifically

Radon is a radioactive gas produced as uranium breaks down in soil and rock. You cannot see it, smell it, or taste it, and long-term exposure is the second leading cause of lung cancer after smoking. Minnesota's glacial soils are unusually rich in the source material, and our sealed-up winters pull soil gas into houses for months at a time. The result, in the Minnesota Department of Health's own data: about 2 in 5 Minnesota homes tested come back at or above 4 picocuries per liter (pCi/L), the level at which the EPA and MDH say fix the home. The national figure is closer to 1 in 15.

Two things follow from that. First, no Minnesota county is a low-radon county; the state maps every county as high radon potential. Second, your neighbor's number tells you almost nothing. Radon depends on the soil under one specific foundation and the pressure balance of one specific house. The county statistics on our county pages tell you how seriously to take the question, not the answer.

Testing: the fifteen-dollar part

A short-term test is a small charcoal kit you set on the lowest level of the home where people regularly spend time, leave for a few days with windows closed, and mail to a lab. Kits run about $10 to $30: at hardware stores, discounted through many county health departments, or on Amazon (First Alert RD1 charcoal kit, lab fee included). That Amazon link is an affiliate link; it costs you nothing extra and supports this site. Long-term tests (91 days to a year) give a truer picture of annual average exposure and are the better follow-up when a short-term result lands in the gray zone between 2 and 4 pCi/L.

Winter is the honest season: the house is closed, the stack effect is strongest, and the reading reflects the months you actually breathe the air. MDH recommends testing every two to five years, after any major renovation, after finishing or moving into a lower level, and after mitigation work to confirm it performs. Our should-I-test checkup turns those rules into a sixty-second verdict.

For a real-estate transaction, do not use a hardware-store kit. Minnesota licenses radon measurement professionals (more below), and a licensed measurement, often with a continuous monitor that records hourly readings and tamper indicators, is what holds up when the result becomes a negotiating point.

Reading the number

4 pCi/L is the action level, not a safety line; the EPA is explicit that no level is known to be safe and suggests considering mitigation between 2 and 4. A result at or above 4 means fix the home: not panic, not move, fix. Radon risk is a function of concentration multiplied by years of exposure, so the reasonable response to a high test is to schedule mitigation in the coming weeks, not to evacuate, and equally not to file the report away and forget it.

Fixing: what mitigation actually is

Nearly every Minnesota mitigation is some form of sub-slab depressurization: a hole is cored in the basement floor, a pipe runs from the gravel under the slab up through the house (or along an exterior wall), and an inline fan pulls soil gas out above the roofline before it can enter the living space. Sump baskets and crawlspace membranes get tied into the same system. A typical Minnesota install runs roughly $1,500 to $2,500, takes about a day, and cuts levels dramatically, often below 1 pCi/L.

Since January 1, 2019, Minnesota law (Minnesota Statutes section 144.4961) requires anyone measuring or mitigating radon in a building they do not own to hold an MDH license, follow state work standards, and notify MDH of each mitigation job. Every licensee, measurement and mitigation, is in our directory, refreshed weekly from MDH's list. Verify the license before you sign, get the post-mitigation test, and keep both documents: the next section explains why they matter at sale time.

Buying or selling: the Minnesota Radon Awareness Act

Since 2014, the Minnesota Radon Awareness Act (Minnesota Statutes section 144.496) has put radon into every residential sale. Before signing a purchase agreement, the seller must give the buyer, in writing: what the seller knows about radon concentrations in the home, including any test records the seller has; whether the home has a radon mitigation system, and if so its description; the statutory radon warning statement; and an MDH radon publication. The disclosure travels with the standard seller's property disclosure under Minnesota Statutes chapter 513.

Notice what the Act does not require. It does not require the seller to test, and it does not require anyone to mitigate, whatever the level. It is a disclosure law: it makes silence and selective memory legally risky, and nothing more. A seller who discloses a known 8 pCi/L result and sells anyway has complied with the Act.

That gap is why the practical advice differs by seat. If you are buying, the inspection period is your radon window: order a licensed measurement alongside the inspection, and if the result is high, negotiate mitigation (a specific, priceable repair) like any other inspection item. If you are selling, an up-to-date test and a documented mitigation system are the cheapest form of deal insurance there is; a surprise result during the buyer's inspection reopens negotiations at the worst possible moment. And a seller who fails to disclose known radon information risks liability under the disclosure statutes (Minnesota Statutes sections 513.52 to 513.60) after closing.

New construction has its own rule: homes built since June 2009 must include passive radon-resistant construction under the Minnesota Residential Code. Passive features lower the odds; they do not guarantee a low level. A test is still the only proof.

Renters, and everyone else the statutes skip

The Radon Awareness Act covers sales, not leases; Minnesota law does not currently require landlords to test or disclose. A renter can still test (kits do not care who holds title), and a high result becomes a conversation with the landlord about mitigation, backed by the general habitability covenants of Minnesota Statutes section 504B.161. MDH's Indoor Air Unit (651-201-4601) is the state resource when that conversation stalls.

The short version

Test every two to five years, in winter, on the lowest lived-in level. At or above 4 pCi/L, hire an MDH-licensed mitigation professional and retest to confirm. Buying: test during the inspection period. Selling: disclose what you know, in writing, before the purchase agreement, and consider testing before you list. Keep every report. None of it is exotic, and the whole path from worry to fixed usually costs less than a fender bender.