Is persistent hazy weather associated with lung cancer? Air pollution has seriously affected our lives and lives, so what exactly is air pollution? According to the definition given by the International Organization for Standardization (ISO), “air pollution (also called atmospheric pollution) is usually a phenomenon in which certain substances enter the atmosphere as a result of human activity or natural processes, presenting sufficient concentration for a sufficient period of time, and consequently endangering the comfort, health and welfare of the human body or the environment”. Currently we know of more than 100 types of air pollutants, both natural and anthropogenic, and the latter is predominant. According to a large number of studies in recent years, air pollution is the main cause of lung cancer formation. Particulate matter (mainly PM2.5), sulfur oxides, nitrogen oxides, polycyclic aromatic hydrocarbons, radon, heavy metals and other pollutants in the atmosphere all contribute to the occurrence of lung cancer. PM2.5 concentrations in Beijing increased by approximately 3% per year between 2006 and 2010. Causing an annual loss of 120 to 240 billion RMB ($19 to $39 billion) to Beijing and surrounding areas. Since December 2012, Beijing has experienced hazy weather for more than 25 days, with PM2.5 concentrations reaching 755 micrograms per cubic meter at one point on January 12, 2013. The concentration of harmful particles in the air reached 36 times the World Health Organization (WHO) safe level. In the Chinese capital, with a population of about 20 million, people were told to stay out as much as possible. Respiratory diseases have increased dramatically and environmental carcinogens, represented by PM2.5, will be strongly associated with the future development of lung cancer, the worst air pollution ever recorded in Beijing. Pollution has become one of the main obstacles to attracting top overseas talent and one of the main drivers of migration for wealthy domestic citizens. Atmospheric pollution has reached dangerous extremes, and it also serves as a warning for Beijing and the country as a whole to strengthen the pace of environmental protection and ecological civilization. While there are certainly meteorological reasons for the formation of hazy weather, inverse weather, humidity, etc., a more important reason is the decline in air quality due to increased environmental pollution caused by population growth and sloppy emissions. In the context of global warming, this pollution situation will undoubtedly intensify if the pollution situation is still not strongly managed. A survey shows that if you breathe in air with a PM2.5 concentration of 670 micrograms per cubic meter for a day, it is equivalent to involuntarily smoking a cigarette. We all know that smoking is harmful to health, but the situation now is that even though you can not smoke, you cannot not breathe. These particulate matters are less mobile and not easily dispersed, and are easily absorbed by the body. Long-term adhesion in the lungs can trigger the development of lung cancer.