January is National Radon Action Month, and in Minnesota, radon is one of the most common potential indoor air quality hazards in homes. Radon is a colorless, odorless gas that seeps up from the earth. Often called “the invisible killer,” radon levels in Minnesota are more than three times the national average. 

According to a recent analysis from the Minnesota Department of Health (MDH), 40% of homes in the state have dangerous levels of the gas, but only 1% to 2% have had their levels tested in the past five years. Dangerous levels are considered 4.0 pCi/L (picocuries per liter) or above, at which the MDH highly encourages fixing the home to reduce radon exposure.

The average radon level in the U.S. is 1.3 pCi/L. As determined by test results, the average indoor radon level of Sherburne Co. is 3.1pCi/L, Wright Co. and Stearns Co. are both 4.5 pCi/L. The average level in Minnesota is 4.2 pCi/L.

“Two in five homes in Minnesota have elevated radon,” said Dan Tranter, environmental health supervisor for the Indoor Air Program for MDH. “It’s the leading cause of lung cancer in nonsmokers, and the second leading cause in smokers.”

Tranter explained Minnesota’s high levels of radon are caused by two factors. First, the state has high levels of uranium in the soil, which breaks down to radium. As radium disintegrates it becomes radon, which is a radioactive gas. The radon then moves up through the soil and into the air.

The second factor is homes in Minnesota are closed up most of the year, and a vacuum effect occurs, especially during the heating season, which draws radon into the home.

“Radon can enter through cracks and gaps in the foundation, even in homes without a basement,” said Tranter. “You can’t zero your exposure, every home will have some levels. But we want our exposure to be as low as possible.”

Because of its high prevalence and potential health risks, MDH recommends every Minnesota home be tested for radon. 

Testing is easy, inexpensive, and takes only three to seven days. Short-term kits can be purchased from local county health departments. In Wright County, tests can be purchased for $5 at Health and Human Services in Buffalo. In Sherburne County, tests can be purchased for $5 at Health and Human Services in Elk River. 

Although winter is the best time for testing, it can be done year-round as long as closed house conditions are maintained. The test kit should hung two to six feet from the floor in the lowest area of the home that is used on a regular basis, such as a bedroom. The test should be left undisturbed for three to seven days, after which it’s sent to a lab for analysis.

If a home is found to have elevated levels of radon, Tranter stressed the only effective method of reduction is to have a radon mitigation system installed. MDH has a list of contractors that specialize in radon mitigation on its website.

 For more information on radon and radon mitigation, visit the Minnesota Department of Health’s website at www.health.state.mn.us/radon.