Radon Testing in Southeast Minnesota: What Buyers Need to Know

Quick answer: Mower County, Olmsted County, and most of southeast Minnesota are in EPA Radon Zone 1 — the highest-risk zone in the United States. The Minnesota Department of Health estimates that 2 in 5 homes in this region exceed the 4.0 pCi/L action level. Every home buyer in Austin, Rochester, Albert Lea, and surrounding cities should test for radon during their inspection.

Why southeast Minnesota has high radon

Radon is a naturally-occurring radioactive gas produced by uranium decay in soil and bedrock. The geology of southeast Minnesota — fractured limestone, dolomite, and shale of the Driftless Area — allows radon to migrate easily from bedrock through soil and into basements.

Combined with our cold winters (which create stack-effect pressure that pulls soil gas into homes), this region has some of the highest residential radon concentrations in the country.

Radon levels by county in southeast MN & northern IA

Average indoor radon levels reported by the Minnesota Department of Health and Iowa DPH:

• Mower County (Austin) — Average 5.8 pCi/L | ~46% of homes above 4.0 pCi/L
• Olmsted County (Rochester) — Average 6.4 pCi/L | ~52% of homes above 4.0
• Freeborn County (Albert Lea) — Average 5.2 pCi/L | ~42% above 4.0
• Steele County (Owatonna) — Average 5.5 pCi/L | ~45% above 4.0
• Rice County (Faribault, Northfield) — Average 6.1 pCi/L | ~50% above 4.0
• Cerro Gordo County, IA (Mason City) — Average 7.2 pCi/L | ~58% above 4.0

For context: the EPA action level is 4.0 pCi/L. The world average outdoors is 0.4 pCi/L. The EPA recommends mitigation at any reading of 4.0 or higher and "consideration" between 2.0 and 4.0.

Why radon is a big deal

The EPA classifies radon as the #1 cause of lung cancer in non-smokers and the #2 cause overall. Long-term exposure to elevated radon kills an estimated 21,000 Americans per year — more than drunk driving.

The good news: radon is detectable with a simple test, and mitigation systems are highly effective. Most installs are a one-time investment that reduces levels to below 1.0 pCi/L.

How we test for radon during a home inspection

We use continuous radon monitors (CRMs) that take hourly readings over a 48-hour test period. Unlike charcoal canisters, CRMs cannot be tampered with, log temperature and humidity, and produce a court-admissible report. Read more about our radon testing service.

What if your test comes back high?

If your radon test exceeds 4.0 pCi/L, you have options:

1. Negotiate mitigation. Most sellers in Mower, Olmsted, and Freeborn counties will pay for mitigation as a condition of sale — it's standard practice.
2. Install yourself after closing. A licensed mitigator can install a sub-slab depressurization system in 4–6 hours. The fan runs quietly, uses very little electricity, and has a 20+ year lifespan.
3. Re-test post-mitigation. A second test confirms levels dropped below action threshold. We provide this service.

Should you bundle radon with your home inspection?

In southeast Minnesota — yes, almost always. Skipping radon in this region is like skipping the brake test on a used car. The marginal cost (a modest add-on) is tiny compared to the lifetime health risk and the real-estate negotiating leverage.

Our Complete Protection Package bundles radon testing with the home inspection, mold testing, thermal imaging, and a sewer scope, with meaningful bundle savings vs. ordering each separately.

Get radon testing scheduled today

Use the instant quote calculator to add radon testing to your inspection in one click. We'll bring the monitor to your appointment and pick it up 48 hours later — results delivered the same day the test ends.