Average Radon Level

Source: MDH Indoor Air Unit 2010-2014. Average U.S. indoor radon level from EPA.

The average radon level in Minnesota (4.6 pCi/L) is more than three times higher than the average U.S. radon level (1.3 pCi/L). Radon is a serious public health issue in Minnesota because our soil has high levels of radon. In winter, home heating systems tend to draw in radon gas from the soil, increasing radon levels inside the home. 


Many counties have high radon levels

Average Radon Test Level

Source: MDH Indoor Air Unit 2010-2014. 87 total MN counties

About 78% of Minnesotan counties have average radon levels in the highest category. Even if your county has a lower average radon level, it is important to test your own home since radon levels can be very different even between homes in the same neighborhood. Minnesotans can order discounted radon test kits.

If a house tests:

  • Between 2-<4 pCi/L, the Environmental Protection Agency and MDH recommend  considering fixing the home to reduce radon exposure
  • At or above 4.0 pCi/L, the  EPA and MDH highly encourage fixing the home to reduce radon exposure

Radon testing is increasing in Minnesota

Annual Number of Properties Tested

Source: MDH Indoor Air Unit 2000-2014.

This chart displays the number of unique properties tested for radon each year. This information is from eight private radon labs that voluntarily report their data to the Minnesota Department of Health. In 2014, there were 24,716 properties in Minnesota tested for radon.

In 2005 a media awareness campaign encouraged Minnesotans to test their home for radon. This may be why there was a high number of properties tested. The Minnesota Radon Awareness Act, January 1, 2014, requires the seller to disclose any knowledge of radon concentrations in the home. The increase in the number of homes tested for radon since 2012 may be due to this new law combined with radon awareness campaigns, local outreach partnerships, and an improving economy. 


Radon levels change with the season

Average Radon Levels by Season

Source: MDH Indoor Air Unit 2010-2014.

Average radon levels rise and fall throughout the seasons due to home ventilation and heating. Radon levels tend to be higher in the winter, but can be high anytime of the year.  It is important to test your home when possible, but be aware of the impact of the season on your radon test results. January is radon awareness month and is a good time to test.