Lung cancer has become the number one killer among cancers in China, and smoking is internationally recognized as one of the most important factors causing lung cancer. Deaths from lung cancer among smokers are about 10 times more than those among non-smokers. In China, 70-80% of lung cancers in men are caused by smoking, and about 30% of lung cancers in women are attributed to smoking and passive smoking. The smoke from a lit cigarette contains more than 3,000 toxic chemicals, the most important of which are nicotine, carbon monoxide, cyanide, many carcinogens present in the smoke tar, radioactive isotopes and heavy metal elements. Tobacco combustion produces benzo(a)pyrene, nitrosamines, cadmium, and a small amount of radioactive elements such as polonium, all of which have carcinogenic effects. There are also phenolic compounds and other cancer-promoting substances. Compared with non-smokers, the risk of lung cancer is on average 4-10 times higher in smokers, and up to l0-25 times higher in heavy smokers. The younger the age at which smoking begins, the longer the duration of smoking, and the greater the amount of smoking, the higher the incidence of lung cancer. The encouraging thing is that the risk of lung cancer caused by smoking decreases each year as you quit smoking. The risk of dying from lung cancer decreases to an average level after 10 years of quitting, and the risk of dying from lung cancer decreases to the level of non-smokers after 15 years of quitting. This shows that when smokers choose to quit at different stages of their lives, their risk of cancer is reduced to varying degrees, and the sooner they do so, the better. Seeing these data, what are you waiting for? Starting from tomorrow, you should really start to take action for yourself and your loved ones. Age of smoking is directly proportional to the incidence of lung cancer: 1. The incidence of lung cancer is 100 times higher for people who have smoked for 20-60 years than for non-smokers; 2. The incidence of lung cancer is 4 times higher for people who have smoked for 15 to 25 years or more than for non-smokers. People at high risk of lung cancer: those who have smoked for more than 20 years, those who started smoking under 20 years old, and those who smoke more than 20 cigarettes a day are at high risk of lung cancer.