Many people spend most of their day indoors, where low concentrations of radon (Rn-222) pose a significant environmental risk. Radon is a gas that decays from uranium (U-238). Its progeny can attach to aerosol and dust, and tends to get into the lungs [1]. In a previous study, 40% of all lung cancer deaths among miners were found to be related with radon progeny exposure. Indeed, 10% of all lung cancers may be caused by exposure to radon indoors: interestingly, these percentages were higher in never smokers than in smokers [2]. Another study proposed that radon poses a higher risk upon prolonged exposure at low doses than shorter exposure at higher doses [3]. Accordingly, the World Health Organization has pronounced radon as the second leading cause of lung