If the test results are above 4.0 pCi/L, this is considered above the US EPA's action level. At this point mitigation is recommended. Generally speaking any amount of radon carries some risk, even at or below the recommended action level. However the risk of lung cancer increases with the higher long-term average radon levels. So you may want to consider radon mitigation even if you level is below 4.0 pCi/L

EPA Map of Minnesota Radon Zones

This is a map that shows the potential for Radon in Minnesota. This map is only predicted levels of Radon. Your house may contain very low levels or may be above the EPA's action level. Also be aware that tests done in other structures around your house are not indicative of Radon levels in your house.

EPA Map of U.S.A.

This is a map that shows the potential for Radon in USA.