Since most people spend the majority of their time at home, home is where radon levels may be of concern. But some argue that this standard may be too strict and that the EPA has overestimated the hazardous effects. It has been argued that the miners were exposed to very extreme concentrations of radon over the course of many years and that their smoking habits were not taken into consideration. Numerous studies are underway on various populations to determine the relationship between concentration, exposure period, and risk of lung cancer. In the mean time, the most effective way of reducing lung cancer risk would be for smokers to stop smoking, and nonsmokers to stay clear of second hand smoke.
Smoking is, afterall, the number one cause of lung cancer.