Executive Yuan Environmental Protection Agency

China's land is narrow and dense, and the density of motor vehicles is high. Therefore, the air pollution caused by traffic has received much attention. Air pollutants emitted by motor vehicles are classified into gas pollutants and particulate pollutants according to their properties, including: carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), sulfur dioxide (SO2), and ozone (O3). suspended particles (PM10) and fine suspended particles (PM2.5).