Variations of aerosol properties due to regional source contributions and impacts on ozone levels: A study in a south China city

Variations of PM₁₀ concentration and particle size distribution owing to the influence of industrial activities in mainland China, biomass burning in South East Asia and dust storms in north-west China, as well as the aerosol impact on surface ozone concentration, have been studied by a combination of analysis of air mass origin (by back-trajectory calculation), remote sensing techniques, regional chemical transport and photochemical box models. The PM₁₀ concentrations in Hong Kong were reduced by 24-57% owing to the industrial downtime during the Chinese New Year period. A photochemical box model coupled with a radiative transfer model has been employed to predict surface maximum ozone concentrations during high aerosol loading days. Increase of aerosol optical depth can lead to 7-32% reduction of surface maximum ozone concentration. Our results emphasise the need for regional cooperation in tackling the local air pollution of Hong Kong. © CSIRO 2010.