1.Passive smoking: (1)Concept: Passive smoking is the non-smoker living and working in the environment where the smoker smokes and the non-smoker inhales the smoke emitted by the smoker. (2)Hazard: Definitely associated with lung cancer.IARC’s epidemiological survey in Europe confirmed that the risk of lung cancer is indeed elevated in adult nonsmokers in the home or workplace, and this risk tends to increase with the degree of exposure in the smoke environment. The degree of risk is proportional to the amount of toxic or carcinogenic substances such as nicotine in body fluids. There is no minimum safe amount of smoking and lung cancer risk; one more point of inhalation is one more point of risk. According to Environment International, smoking in the home and workplace causes 46,000 non-smoking deaths each year, including 3,000 deaths from lung cancer. Women are 2.4 times more likely to die because their husbands smoke than their husbands who do not smoke, and 3.4 times more likely if their husbands smoke up to 20 or more cigarettes a day. A survey in Shanghai showed that women who live with a non-smoking husband have an average 19% higher risk of lung cancer, and those who live with a heavy-smoking husband for a long time have a 30% higher risk, and tobacco contains more than 3,000 ingredients, more than 50 of which are carcinogenic. The polycyclic aromatic hydrocarbons, benzo(a)pyrene, dibenzanthracene, nitrosamines, nicotine and heterocyclic amines produced by combustion in tobacco are all carcinogenic substances. In addition, tobacco also contains a large number of carcinogenic substances such as phenolic compounds, terpenoids and radioactive elements, which play a large role in the final formation of lung cancer. 2.Air pollution (1) general air pollution. The severity of atmospheric pollution is consistent with the distribution of high and low mortality rates of lung cancer. Industrial and mid-city areas are higher than non-industrial and suburban areas. (2) Local pollution. Cooking oil smoke also contains lung cancer-causing substances such as benzo(a)pyrene. It may be related to the incidence of lung cancer in women in China.