Radon is the second leading cause of lung cancer, after smoking. The U.S. Environmental Protection Agency (EPA) and the Surgeon General strongly recommend taking further action when the homes radon test results are 4.0 pCi/l (picocuries per liter of air) or greater. Radon levels less than 4.0 pCi/l still pose some risk and in many cases may be reduced. The annual national average indoor radon level is about 1.3 pCi/l while annual outdoor radon levels average 0.4 pCi/l. The higher a homes radon level, the greater the health risk to you and your family. Smokers, former smokers, and individuals with a family history of lung cancer are at especially high risk. EPA recommends that you use an NRPP or NRSB or State licensed contractor trained to fix radon problems. You can contact your state radon office to obtain information, including a list of State-approved radon contractors who can fix or can help you develop a plan for fixing the radon problem.

• Fix the building if test results indicate occupants may be exposed to radon concentrations that meet or exceed the EPA recommended action level of 4 pCi/L. 
• Consider fixing the building if test results indicate radon concentrations greater than half the action level (2-4 pCi/L)
• Retest the building at least every five years if no mitigation system is installed.
• Post-mitigation requirements:  Conduct a short-term radon measurement no sooner than 24 hours after a mitigation system is operational and within 30 days after installation of the system(s) to provide an initiation measure of radon-reduction system effectiveness.
• If radon mitigation has been conducted, testing is recommended at least every two years to ensure the system remains effective.
• Retest the building in conjunction with any sale of new or existing buildings.

MN MDH Phone - 651-201-4601

email: health.indoorair@state.mn.us

website: http://www.health.state.mn.us/divs/eh/indoorair/radon/index.html

For homes with low radon concentrations, it is recommended to retest is any of the following apply:

• If the home was unoccupied during the test, the home should be retested after occupancy;
• If the home is located in an area of karst or glacial moraine geology, it should be retested over 12 months. 
• If the initial test was conducted during abnormal climatic events such as, prolong drought.  
• If occupied by a new owner;
• If the initial test was less than 4 pCi/L, retest every very five years after initial testing;
• If a new addition is added;
• If an alteration is made that could change the ventilation pattern;
• If major cracks or penetrations occur in the foundation walls or slab;
• If significant nearby construction blasting or earthquakes occur;
• If changes are made or happen to an installed mitigation system; or
  If a ground-contacted area is occupied that was not previously tested.