Lung cancer has the highest incidence and death rate of any cancer in China. 90% of all lung cancers are associated with smoking. However, many non-smokers still get lung cancer, why? Besides smoking, there are four other risk factors for lung cancer. 1. Age As we grow older, the cells in our body will inevitably be damaged and our body immunity will decrease, so the probability of getting lung cancer will naturally increase. Lung cancer is relatively rare in people under 40 years old, but mostly develops in people over 50 years old. 2. Air pollution Various studies only tell us that the incidence of lung cancer is related to haze. However, no authoritative study has ever given a clear conclusion on how big this “correlation” is. In fact, compared with smoking or even cooking, haze is not the main cause of lung cancer. The prevention is still necessary. Indoors, you can buy an air purifier; outside, you can wear an anti-haze mask. 3. Second-hand smoke Whether at home or at work, passive inhalation of second-hand smoke will increase the probability of cancer. There is no so-called “safe level” of second-hand smoke exposure, and any dose of second-hand smoke intake will cause effects, and the more you inhale, the greater the danger. Women who cook every day have a 2-fold increase in lung cancer incidence; cooking methods also have an impact. For women who are keen on frying and stir-frying, their lung cancer risk is higher than that of women who cook, because the higher oil temperature during frying and stir-frying will produce some carcinogens (such as polycyclic aromatic hydrocarbons and dust particles). Chinese cooking is all about color and flavor, and deep-frying, stir-frying and dry-frying are often essential processes. The resultant oil smoke is a major risk factor for getting lung cancer.