Radon in Minnesota Homes: What Every Homeowner and Buyer Should Know
By Coleman Home Inspections | Serving Duluth, Cloquet, Superior & Surrounding Communities
Radon is one of the most common environmental concerns affecting homes throughout Minnesota, yet many homeowners know very little about it.
According to the Minnesota Department of Health (MDH), more than two out of every five Minnesota homes have radon levels that pose a significant health risk.
Unlike many household hazards, radon cannot be seen, smelled, or tasted. Testing is the only way to determine whether elevated levels are present in your home.
Fortunately, radon testing is relatively simple, and elevated levels can usually be reduced through a properly installed mitigation system.
What Is Radon, and Where Does It Come From?
Radon is a naturally occurring radioactive gas produced by the breakdown of uranium and radium in soil and rock.
As radon moves through the ground, it can enter buildings through openings in foundations, cracks in concrete floors, sump pits, crawl spaces, and other pathways.
Once inside, radon can accumulate in the indoor air.
Long-term exposure to elevated radon levels increases the risk of lung cancer. The Minnesota Department of Health identifies radon as the leading cause of lung cancer among people who have never smoked.
The risk increases with higher concentrations and longer exposure periods.
For additional information, visit the Minnesota Department of Health’s Radon in Homes page.
Why Is Radon So Common in Minnesota?
Minnesota’s geology and cold climate contribute to elevated indoor radon levels.
During our long heating season, differences in air pressure between the interior of a home and the surrounding soil can draw radon into the building.
It’s important to understand that radon is not limited to older homes, homes with basements, or homes in particular neighborhoods.
Newer homes can have elevated radon levels. Homes built on slabs or over crawl spaces can also be affected.
Even neighboring homes can have significantly different radon concentrations.
A previous test from another house in your neighborhood cannot tell you what the radon level will be in yours.
The Minnesota Department of Health provides an interactive resource showing radon testing results throughout the state:
Understanding Radon Test Results
Radon concentrations are measured in picocuries per liter of air, abbreviated pCi/L.
The Environmental Protection Agency and Minnesota Department of Health use the following guidance when evaluating radon levels:
Radon Level | Recommended Action |
Below 2.0 pCi/L | Retest periodically |
2.0–3.9 pCi/L | Consider mitigation to further reduce exposure |
4.0 pCi/L or higher | Mitigation is recommended |
These recommendations are based on appropriately conducted testing and, when applicable, follow-up testing.
It’s important to recognize that 4.0 pCi/L is an action level, not a dividing line between safe and unsafe air. Radon exposure carries some degree of risk at any concentration, and reducing exposure is always beneficial.
How Is Radon Testing Performed?
There are two primary approaches to measuring radon concentrations.
Short-Term Testing
Short-term tests typically last between two and seven days. These tests provide a relatively quick measurement and are commonly used during real estate transactions.
Licensed radon measurement professionals may use calibrated continuous radon monitors that record measurements throughout the testing period.
Long-Term Testing
Long-term tests measure radon concentrations for at least 90 days and provide a better estimate of average exposure over time.
Because radon concentrations can fluctuate with weather, seasonal conditions, and building operation, long-term testing can be particularly useful for homeowners.
The Minnesota Department of Health recommends testing homes every two to five years and after certain renovations or changes to the home’s heating, ventilation, or energy efficiency.
Radon Testing During a Minnesota Home Purchase
Minnesota has specific requirements concerning radon disclosure during residential real estate transactions.
Under the Minnesota Radon Awareness Act, sellers must disclose their knowledge of radon concentrations and provide applicable testing information to prospective buyers.
However, Minnesota does not require every home to be tested for radon before it is sold.
The Minnesota Department of Health strongly recommends radon testing during real estate transactions.
Professional real estate testing typically involves a minimum 48-hour measurement under specified closed-house conditions.
When testing is performed professionally in Minnesota, the measurement provider must hold the appropriate Minnesota Department of Health license.
What Happens if Elevated Radon Is Found?
An elevated radon result does not necessarily mean a home is unsuitable for purchase or occupancy.
Radon mitigation is a well-established method of reducing indoor concentrations.
Most commonly, mitigation systems use a continuously operating fan and piping to draw radon-containing soil gases from beneath the foundation and discharge them safely outdoors.
The design depends on the home’s foundation and construction.
Properly installed systems can often reduce radon concentrations substantially, sometimes to levels below 2.0 pCi/L.
Minnesota requires radon mitigation professionals working on homes they do not own or lease to be appropriately licensed.
Should You Test Your Home?
Whether you’re purchasing a home or have lived in the same house for decades, radon testing is worth considering.
A home that previously tested low can experience changes in radon concentrations over time. Renovations, changes in mechanical systems, and modifications to the building envelope can affect how soil gases enter a home.
The Minnesota Department of Health recommends that every Minnesota home be tested, regardless of age, foundation type, or location.
The only way to know your home’s radon concentration is to test.
Learn More from the Minnesota Department of Health
For additional information about radon, testing procedures, health risks, and mitigation, we encourage homeowners to consult the Minnesota Department of Health.
Coleman Home Inspections
With more than 15 years of experience and thousands of home inspections completed throughout Northern Minnesota and Northwest Wisconsin, Coleman Home Inspections helps homebuyers better understand the properties they’re purchasing.
We offer professional radon testing as an additional service during home inspections.
Serving Duluth, Cloquet, Hermantown, Esko, Carlton, and surrounding communities.
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