Published April 28, 2025
Complete Guide to Radon Testing in Rochester MN
Radon is the invisible threat lurking beneath Rochester homes. This naturally occurring radioactive gas is the second leading cause of lung cancer in the United States, and Olmsted County has some of the highest radon concentrations in Minnesota. Yet many Rochester homeowners and buyers remain unaware of the risk. Understanding how radon enters your home, why testing is essential, and what to do about elevated levels can literally save your life.
What Is Radon and Where Does It Come From?
Radon is a radioactive gas produced by the natural decay of uranium in soil, rock, and water. It is colorless, odorless, and tasteless, making it impossible to detect without specialized testing equipment. Rochester's geological foundation of limestone bedrock and uranium-bearing granite creates conditions that generate significant radon concentrations. The gas enters homes through any opening in the foundation including cracks, construction joints, gaps around pipes and wires, sump pit openings, and the natural porosity of concrete.
Rochester's Radon Risk
The Minnesota Department of Health has identified Olmsted County as Zone 1, the highest radon risk classification, with predicted average indoor levels above 4 pCi/L. In our experience inspecting homes throughout the Rochester area, approximately two out of every five homes we test show radon levels at or above the EPA action level. This risk exists regardless of home age, construction type, or neighborhood. We have measured elevated levels in brand-new homes in Meadow Crossing just as often as in century-old homes near downtown.
How Radon Testing Works
During a home inspection, we deploy a continuous radon monitor in the lowest livable level of the home. The monitor takes hourly readings over a minimum 48-hour period, providing both an average concentration and a timeline showing how levels fluctuate. Testing must be conducted under closed-building conditions, meaning windows and exterior doors stay closed except for normal entry and exit.
The EPA recommends action when radon levels reach 4 pCi/L or higher. However, there is no truly safe level of radon exposure, and the EPA suggests considering mitigation for levels between 2 and 4 pCi/L as well. For real estate transactions in Rochester, radon testing is a standard add-on service that provides crucial information about the property.
Understanding Your Results
Radon levels are measured in picocuries per liter (pCi/L). The average outdoor level is about 0.4 pCi/L. The average indoor level nationally is about 1.3 pCi/L. In Rochester, we commonly see indoor levels ranging from 2 to 15 pCi/L, with some homes testing as high as 20 pCi/L or more. The higher the level, the greater the health risk and the more urgent the need for mitigation.
Radon Mitigation in Rochester
The most common and effective mitigation method is active sub-slab depressurization. A certified radon mitigator drills a hole through the basement floor, inserts a PVC vent pipe, and runs it through the house and out above the roofline. A small inline fan creates negative pressure beneath the slab, drawing radon from under the foundation and exhausting it harmlessly above the roof where it dissipates in outdoor air.
This system typically reduces radon levels by 80 to 99 percent. The fan uses about the same electricity as a light bulb, running continuously year-round. Post-installation testing confirms the system is working effectively, and periodic retesting every two years is recommended to verify continued performance.
Radon in Real Estate Transactions
In the Rochester housing market, radon testing is almost expected as part of the buying process. When elevated levels are found, buyers typically request the seller install a mitigation system or provide a credit for installation. Because mitigation is relatively affordable at $800 to $1,500, this issue rarely kills deals but does need to be addressed. Sellers who proactively test and mitigate before listing eliminate this negotiation point entirely.
Get Your Rochester Home Tested for Radon
Professional radon testing with continuous monitors. Results included in your inspection report.
Call (507) 721-0922