Nitric oxides, no and no2, contribute to air pollution, acid rain, and the depletion of the ozone layer. after no forms in the combustion chamber of an automobile engine, it reacts further with oxygen to form no2. the reaction is given by

After nitrogen oxide forms in the combustion chamber of an automobile engine, it reacts further with oxygen in the atmosphere to form nitrogen dioxide. Nitrogen dioxide is considered to be an air pollutant that is a result of various process.  The reaction is expressed as follows:

2NO + O2 --> 2NO2