The main component of photochemical smog is peroxy acetyl nitrate (PAN). There are three components involved ozone, nitric acid acrolin and formaldehyde. The main component of oxidising smog or photochemical smog is PAN. (b) The main component of photochemical smog is peroxy acetyl nitrate (PAN).There are three components involved ozone, nitric acid acrolin and formaldehyde.The main component of oxidising smog or photochemical smog is PAN.