Smoking is a major risk factor for lung cancer, but about 20% of my patients are not in the smoking population, nor are they long-term passive smokers. This is because lung cancer in nonsmokers is a completely different disease from lung cancer in smokers because they have different molecular signaling pathways. In addition, lung cancer in nonsmokers has a higher survival rate, occurs at different ages and is mostly adenomatous. The World Health Organization (WHO) in 1987 and the U.S. Environmental Protection Agency (EPA) in 1988 successively listed radon gas as a carcinogenic substance. Radon gas is a colorless and odorless inert gas. Indoor radon gas mainly comes from granite, cement, gypsum and other building materials, water and gas supply equipment, especially newly renovated houses. Indoor radon gas is the second major risk factor for lung cancer among smokers and the first major risk factor for lung cancer among non-smokers. Radon gas, being a gas, may be inhaled into the respiratory tract and remain there, slowly accumulating; radon, being radioactive, accumulating in the respiratory tract becomes a radioactive source, continuously radiating the lungs, which may lead to lung cancer. However, radon in the atmosphere, because of its extremely low concentration, generally does not lead to lung cancer. It can be seen that indoor radon exposure will raise the risk of lung cancer among non-smokers, so how can we reduce or eliminate indoor radon gas? 1.When building houses or choosing sites, we should avoid areas with high radioactive content of uranium and radium in the rock and soil; before purchasing houses, we can ask relevant institutions to do radon gas test to control and prevent from the source. 2.Close the gaps of the ground and walls as much as possible when renovating to reduce the amount of radon gas leakage. 3.Ventilation is the simplest and most effective way to reduce indoor radon concentration and improve air quality. Experts suggest that rooms should be opened more often for ventilation, and ventilating fans and hoods should be turned on in time when bathing and burning dishes using natural gas. 4.When decorating, try to reduce stone, tile and other materials that are easy to produce radiation and radon gas.