Smoking Smoking is the most important risk factor of lung cancer. There are more than 3,000 kinds of chemical substances in tobacco, among which, multi-chain aromatic hydrocarbons and nitrosamines have strong cancer-causing activity. Almost all the lung cancer patients are related to smoking. Smoke is an extremely acidic substance, which can easily lead to acidification of the human body, and an acidic body is easy to induce cancer. 2.Environmental Factors For example, in Yunnan Province, for example, in the old and Xuanwei areas, which are famous for the high incidence of lung cancer in the world, radon, tin, arsenic, toluene and other carcinogenic substances have made this area a high incidence area of lung cancer. 3. Atmospheric Pollution There are a lot of carcinogenic harmful substances containing benzo(a)pyrene in the environment of industrial and transportation developed areas, which makes the incidence rate of lung tumor remain high. Occupational factors Long-term exposure to radioactive substances such as uranium, radium and its derivatives, carcinogenic hydrocarbons, arsenic, asphalt, petroleum, asbestos, mustard gas, etc. Due to the change of dietary structure and living habits of human beings, the metabolism and circulation slow down as a result of acidification of the body and the overall decline of immune function, which gives these radioactive elements an opportunity to take advantage of and induces the cancerous transformation of cells. 5.Internal factors such as family heredity, lowered immune function, metabolic activity, endocrine dysfunction, etc., will play a certain role in promoting the development of lung tumor. 6.Chronic lung diseases, such as tuberculosis, silicosis, pneumoconiosis, etc., can coexist with lung cancer, and the occurrence of these chronic diseases is caused by acidification of lung cells, cell hypoxia and reduced cell activity.