Radon is an odorless, tasteless and invisible gas produced by the decay of naturally occurring uranium in soil and water. Exposure to radon is the second leading cause of lung cancer after smoking.  Radon is found in outdoor air and in the indoor air of buildings of all kinds.  If you have a Radon leak that is under your house no air purifier will be able to stop Radon from coming into your home.   It is very important that measures be taken to stop the leak of Radon from coming into your home.  Here's a link from Environmental Protection Agency (EPA) on what steps to take: http://www.epa.gov/radon/pubs/consguid.html#reductiontech.  Once the leak is under control an Aireox air purifier can be used