Characterisation of aerosols in Hong Kong with an emphasis on a non-urban site, Cape D'aguilar

Abstract

The number one air pollution problem in Hong Kong is aerosols but their nature is not fully understood. There is a major knowledge gap with respect to non-urban aerosols. The aim of this study is to provide a relatively complete picture of the aerosol in Hong Kong by studying the background, local emissions, transboundary transport and aerosol episodes. Cape D'Aguilar station was established in a non-urban area to measure both TSP and PM₁₀. Aerosol background for anthropogenic species in this region was established in the summer, the values were substantially lower than the yearly averages from 65% to 97% reductions. Whereas in winter, the aerosol level was much enhanced. This may be the result of transboundary transport from the Asian continent, which could be viewed as a huge emission area located upwind of Hong Kong. The similarity of the profiles of aerosols in urban and non-urban areas may provide further evidence to support the presence of transboundary transport. As far as local emission is concerned, its contribution was higher in industrial areas (Kwun Tong and Tsuen Wan) than residential areas (Shatin). In addition, the formation of aerosol episodes was estimated to be attributable to two causes, northeast monsoon and tropical cyclone.