Photochemical smog
From Environmental Technology
Photochemical smog is a mixture of pollutants which includes particulates, nitrogen oxides, ozone, aldehydes, peroxyethanoyl nitrate (PAN), unreacted hydrocarbons, etc. The smog often has a brown haze due to the presence of nitrogen dioxide. It causes painful eyes.
The Cause
The condition needed for the formation of the smog are present in modern cities. They included sunlight, hydrocarbons, nitrogen oxides and particulates which act as catalyst.
These are the equations in the formation of photochemical smog.