Minnesota is unique to Radon due to its geology and cold climate. Minnesota winters can change the pressurization of soil beneath the home which tend to draw in radon gas into the home. The MN Department of Health states that only 1-2% of Minnesota homes are tested annually. If you are planning to make any improvements to the footprint of your home, of if you are changing the HVAC system, we would recommend that you do test again for Radon.
Here is the link for an article that I found informative from the MN Department of Health. https://www.health.state.mn.us/news/pressrel/2024/radon010824.html