Silent invader

Southwest Minneapolis is a hot spot for indoor radon levels; the Minnesota Department of Health offers help

It is colorless, odorless, and tasteless — undetectable to human senses. Yet according to the U.S. Environmental Protection Agency, radon kills an average of 21,000 people per year and is the leading cause of lung cancer in the United States for nonsmokers.

“Obviously this is a terrible thing to happen to somebody who is thirty, never smoked and diagnosed with one of the most terminal forms of cancers,” says Walt Fitzmaurice, owner of the Minneapolis-based professional mitigation service Advanced Radon Services. He gets calls every year from lung cancer patients who attribute their illness to radon. “It hits home on a gut level about the importance of testing homes,” he says.

Radon is a form of radiation that is released through the natural decay of uranium and radium, common minerals found in soil. Gases move through the ground into the air, seeping into houses through cracks and holes in home foundations. Long-term radon exposure can be disastrous.

Minnesota residents should be especially vigilant, as the state has the fourth highest radon concentration in the country. In fact, the Minnesota Department of Health (MDH) estimates that one out of every three homes in the state has radon levels high enough to warrant concern. “We have one of the most progressive radon programs and were the first to pass a statewide radon resistant construction law,” says Andrew Gilbert, a MDH Indoor Health Unit project analyst. “But I don’t think we can stress enough how important it is to test.”

Southwest hot spots

Radon is measured in a picocurie — the amount of radioactivity per one liter of air (pCi/L).

The EPA divides radon levels into three zones. Zone one has the lowest radon potential, with levels under 2 pCi/L. Zone two shows moderate potential, with levels between 2 and 4 pCi/L. Zone three marks the highest potential, or levels greater than 4 pCi/L. Hennepin County falls within zone three.

The average indoor radon level is about 1.3 pCi/L. Yet Fitzmaurice suggests that several Twin Cities hot spots could far exceed that average, including a broad swath of Southwest Minneapolis. His observations are supported by testing results from the MDH, which shows that neighborhoods in the 55416 zip code potentially have a slightly higher source of radon compared to other areas of Southwest Minneapolis.

Minnesota has an elevated risk due to the rich, uranium-filled soil. The prevalence of radon can also be attributed to the state’s infamous weather. When windows are tightly closed for months at a time, outside air is unable to circulate or dilute radon gases. Also, a phenomenon known as the “heat stack effect” contributes to excessive radon build-up. Home heating causes warm air to rise. This pressurizes upper levels of the house. The depressurized lower level then acts as a vacuum, pulling radon gases into the house. The heat stack effect compounds throughout the winter, when radon levels can be up to 20 percent higher than other seasons of the year.

The geologic location of a house is more important than its age. “New, old, tight, loose, big, small… it can be anywhere. Radon has nothing to do with the quality or age of the home,” Fitzmaurice says.

It’s best to test

Basements are often used as living spaces in Minnesota homes but pose the highest radon risk. Tim Langlais of Kenny chose professional mitigation after test results showed excessive levels of radon in his basement. “As a new homeowner, I was going through all of the materials I could to educate myself about keeping a safe and healthy home. This is something you should check,” he says.

What can be done? As a homeowner, be proactive. Purchase a radon test kit for under $20 at home supply stores or through the MDH. There are two types of tests: short-term and long-term. Use a short-term test for the most basic form of detection. If radon levels are above 4 pCi/L, follow up with a long-term test for a more precise average. If long-term results measure greater than 4 pCi/L, call a professional mitigation service to discuss further options.


Radon testing and mitigation resources can be found on the Minnesota Department of Health website,

The MDH also offers a one-day radon mitigation course for homeowners. Participants are expected to have basic carpentry skills and will learn how to install an effective radon mitigation system in their own homes with the help of a professional mitigator.

The cost is $600. The MDH estimates that the average cost of professional mitigation is $1,500–2,000. Send an e-mail to [email protected] for dates and times.