Lung cancer is a leading cause of death in the West, its greatest anamoly being that it is primarily self-inflicted: over 80% of lung cancers are caused by smoking; next is residential radon, a by-product of naturally-occurring breakdown of radium, which comes from decaying uranium. One in fifteen homes has been calculated to have ambient radon levels exceeding safe levels. Lastly, comes work-related carcinogens - again, self-infliction.