In August I wrote a blog post on the importance of testing for Radon because of a recent experience with a crazy high radon reading in one of my listing.
According to a proclamation signed by Governor Granholm last year, one in eight homes in Michigan (EPA's map of Michigan radon zones) have elevated levels of radon. Homes with 4 picoCuries per liter (pCi/L) or higher should be remediated. Consider purchasing a radon detection kit if it wasn't part of the home inspection process when you bought your home.
For more information about radon, check out these sources:Reducing Radon Risks, Michigan Department of Environmental Quality
A Citizen's Guide to Radon: The Guide to Protecting Yourself and Your Family from Radon,
U.S. Environmental Protection Agency
EPA Video Radon Discussion