The rapid development of modern industry has accompanied with the uncontrolled emission of inorganic and organic compounds into the atmosphere, resulting in the air pollution globally. In the past decades, different types of technologies and products have been developed to fight again the air pollution. In this Chapter, the current situation of global air pollution will be overviewed, and then the main types and causes of air pollutants will be introduced. The formulation and evolution of air quality standards in WHO and some countries as well as the emission standard of various industries will be provided, which to some degree represents the development levels and future directions. Also, the standards of civilian gas cleaning products are also involved.