From where does ozone come in the photochemical smog?
The composition of photochemical smog is nitrogen oxides, Volatile organic compounds (VOC), ozone, PAN i.e. peroxyacetyl nitrate.
nitrogen oxide present in the smog undergoes dissociation in the presence of sunlight to NO and nascent oxygen (O)
NO2 (g) → NO (g) + O (g)
The nascent oxygen reacts with oxygen gas to form ozone gas along with inert gas.
O (g) + O2 (g) + M → O3 (g) + M(inert gas)