Which one of the following is not a common component of photochemical smog?
Ozone
Acrolein
Peroxyacetyl nitrate
Chlorofluorocarbons
Photochemical smog is a mixture of air pollutants that have been chemically altered into further noxious compounds by exposure to sunlight. The main components of photochemical smog are nitrogen oxides, Volatile Organic Compounds (VOCs), tropospheric ozone, and PAN (peroxyacetyl nitrate).