These secondary pollutants are damaging to plant life and lead to the formation of photochemical smog. PAN is primarily responsible for the eye irritation so characteristic of this type of smog. The figure outlines representative reactions leading to the formation of photochemical smog.
Radicles are atoms or molecules with unpaired electrons.
They are very reactive chemically. 2 O and, to a lesser extent, converting nitrogen oxides to N 2 and O 2 .