Final answer:
Peroxyacyl nitrate (PAN) is a pollutant found in automobile exhaust, coal-based power plant flue gas, exhaust of nitric acid plants, and exhaust of sulphuric acid plants.
Step-by-step explanation:
Peroxyacyl nitrate (PAN) is a pollutant that is found in automobile exhaust, flue gas of coal-based power plants, and the exhaust of nitric acid plants and sulphuric acid plants.
PAN is formed when nitrogen oxides (NOx) react with volatile organic compounds (VOCs) in the presence of sunlight, leading to the formation of brown, photochemical smog.