Tobacco is harmful to the human body in many ways. For example, the smoke passes through the chimney, and over time, a thick layer of soot will accumulate on the chimney wall. Cigarettes enter the body, through the mouth, respiratory tract, digestive tract, all organs of the body may be damaged by tobacco. Smoking is the main risk factor for lung cancer, cardiovascular disease, stroke, coronary heart disease and chronic lung tissue disease. The most harmful effect of smoking is lung cancer, especially central lung cancer. Tobacco is both a “chemical weapon” (containing more than 3,000 chemical components) and a “radiological weapon”, generally speaking, the content of radioactive substances in cigarettes is 20 times higher than in food, and 30 times higher than in vegetables and fruits. The radioactive substances contained in cigarettes can release high-energy rays that directly kill human tissue cells. People who smoke a pack and a half of cigarettes a day, their lungs are subject to the amount of radiation a year, cumulatively equivalent to receiving 300 chest X-rays. The world’s medical community, after large-scale research and studies, has irrefutably confirmed from an epidemiological point of view that smoking is the main culprit of lung cancer. Smoking is the primary risk factor for lung cancer, and 87% of deaths due to lung cancer are caused by smoking (including passive smoking). The mortality rate of lung cancer in male smokers is 8 to 20 times higher than that of nonsmokers. In addition, smoking has a dose-effect relationship with the occurrence of lung cancer, with the incidence of lung cancer being 227/100,000 for 25 or more cigarettes per day; 139/100,000 for 15-24 cigarettes; and 75/100,000 for 1-14 cigarettes. Smoking can produce more than 60 kinds of carcinogenic substances, among which the main ones closely related to lung cancer are polycyclic aromatic hydrocarbons, arsenic, benzene and nitrosamines. These carcinogens can cause damage to the genetic material of bronchial epithelial cells through different mechanisms, triggering a series of important events that cause uncontrolled cell growth and regulation, and eventually leading to cell carcinogenesis. Typically, increases in lung cancer mortality have occurred 20 to 30 years after the smoking epidemic. Tobacco consumption in China peaked in the 1990s, with a 4-fold increase in per capita tobacco consumption compared to the 1950s, and is still at its peak. Because of the lagged effect of smoking on health, deaths from smoking-related diseases such as lung cancer are now a consequence of tobacco consumption in the 1970s to 1980s population. The consequences of present-day tobacco consumption will be evident in the next 20 to 30 years, and mortality from lung cancer and other diseases will continue to rise. The incidence and mortality of lung cancer in China has been on a significant upward trend. in the 1990s compared to the 1970s, the mortality rate of lung cancer in China increased by 111.85%. By the beginning of this century, the mortality rate of lung cancer had climbed from the 4th to the 1st cause of cancer death in the 1970s. Because of the large number of exposed people, the rising trend will continue for at least 20-30 years. It is expected that in 2025, the number of people dying from lung cancer alone in China will be close to 1 million per year. The danger of lung cancer in China is staggering! In the 20 years between the 1970s and 1990s, the death rate from lung cancer doubled. By the beginning of this century, lung cancer had risen from the fourth to the first place in the ranking of malignant tumors. In urban areas, one out of every four deaths is due to cancer, and one out of every three to four deaths due to cancer is due to lung cancer.