Nitrogen oxides play an important role in the production of photochemical smog, so the control of nitrogen oxides is of great significance for improving air quality. Due to the different working principles of gasoline vehicles and diesel vehicles, the control technology for nitrogen oxides is also different. Fortunately, the current technology for the control of nitrogen oxides in motor vehicles is mature and has been widely used in developed countries. In addition, to control nitrogen oxides in motor vehicles, while selecting and using appropriate technologies, relevant policies and safeguards are also necessary.

The exhaust pollutants of gasoline and diesel vehicles include nitrogen oxides. The nitrogen oxides specified in the emission regulations mainly include nitrogen monoxide and nitrogen dioxide. Since nitrogen oxides play an important role in the production of photochemical smog, the country has made the reduction of nitrogen oxides a binding indicator in the "Twelfth Five-Year Plan".

The pollution of motor vehicles to the environment mainly comes from exhaust emissions. The main exhaust pollutants of gasoline vehicles are carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NOx); exhaust pollutants of diesel vehicles include particulates in addition to carbon monoxide, hydrocarbons and nitrogen oxides emission.

Another important use of ozone is for water...