The pollutants in emissions
Polluting substances are produced during the combustion process due to the impurity of fossil fuel.
The main pollutants released by diesel engines are:
Nitrogen oxides (NOx): Formed during combustion at high temperatures (usually above 2912°F/1600°C) when molecular nitrogen (N2) and oxygen (O2) disassociate into their atomic states and react.
Particulate matter (PM): Composed of minute carbon particles and other toxic substances, PM results from an incomplete fuel-burning process, that occurs during combustion at low temperatures.