Ozone formation downwind of an industrial source of hydrocarbons under European conditions

A photochemical trajectory model is used to describe the ozone formation in an air parcel as it passes over an imaginary large industrial hydrocarbon source located in southeast England. The hydrocarbon emission source strengths covered the range 0.4–20 t h−1 and the additional ozone formation amounted to up to 25 ppb over and above the base case with no emission. This additional ozone formation was characterised for each of 119 separate organic compounds using a highly sophisticated Master Chemical Mechanism involving over 2400 chemical species and over 7100 chemical reactions. Each organic compound formed a different amount of ozone downwind. Ozone-equivalent emission ceilings OECs were estimated for each organic compound, varying from 2 t h −1 for the most reactive hydrocarbon studied, 1,3,5-trimethylbenzene, to 1400 t h−1 for methyl chloride, the least. The long chain n-alkanes had anomalously low reactivity because of their propensity to form stable and unreactive alkyl nitrates which reduced the availability of NOx within the air parcel.