Lung cancer, characterized by uncontrolled cell growth in tissues of the lung, is one of the leading causes of cancer mortality worldwide. Many etiologic factors for lung cancer tumorigenesis have been identified to date, such as smoking and exposure to radon, cooking fumes and asbestos. Atmospheric pollution has become increasingly heavy in China in recent years. Accordingly, greater numbers of people are paying attention to the air quality around them. PM2.5 (particulate matter with a diameter of 2.5 micrometers or less), which is one of the most important indicators for measuring air quality, can penetrate and be retained in lung tissue. It is believed that PM2.5 may represent a new type of etiological factor for lung cancer. This study constitutes the analysis of the association between PM2.5 and lung cancer. Genes related to small/nonsmall cell lung cancer were evaluated by assigning scores to measure the impact caused by PM2.5. Analyses of small/nonsmall cell lung cancer genes with high scores revealed that it is theoretically possible that PM2.5 is an etiologic factor for lung cancer. Our results provided new insights of the relationship between lung cancers and air pollution.