Non-negligible contribution of high-level volatile sulphur compounds to ozone photochemical formation in an industry zone in the North China Plain

The increasing amount of ozone (O 3 ) pollution in China is attracting extensive scientific attention globally. This study presents direct evidence that high concentrations of volatile sulphur compounds (VSCs) accelerate the photochemical production of O 3 . We analysed three high O 3 cases (Cases I, II, and III) in which the O 3 concentrations were high but the compositions of O 3 precursors differed. An analysis of the O 3 precursors and the magnitudes of the associated ROx (ROx = ·OH + ·HO 2 + ·RO 2 ) reactivities amongst three cases revealed that VSCs may play an important role in O 3 production. Case I showed high loadings of VSCs, mainly dimethyl sulphide (DMS), and the simulated diurnal average concentration of radicals and the net O 3 production rate were higher than those in Cases II and III, reflecting the higher photochemical reactivity and oxidation capacity of Case I. Although O 3 was mainly produced from the oxidation of aromatics in all cases, the oxidation of DMS was an important contributor to O 3 formation in Case I (14%) and Case III (25%). The combined analyses indicated the contribution of DMS to O 3 production in industrial areas and suggested the urgent need to measure related VSCs during field campaigns in another atmospheric environment to verify this phenomenon.