Exhalates from combustion engines

During the operation of a combustion engine, harmful substances are produced essentially from four main sources of the motor vehicle  

The following substances are all present in exhaust gases of combustion engines  

Some of the substances mentioned are concerned in the formation of secondary harmful species ozone, peracyl nitrate, singlet oxygen and solid aerosols in the atmosphere, which are components of the white photochemical smog of the California variety. Sulphur dioxide in the air is partially further oxidized to sulphur trioxide and hence sulphuric acid. These substances, together with soot are components of the black smog of the London type. 

In Table 5.28, relative abundance is given of main components of exhaust gases for characteristic conditions of the petrol and diesel engine load. 

Type of engine Component of exhaust gas Idling Acceleration Partial load Deceleration 

---