This book presents studies of atmospheric aerosols in Hong Kong in the Pearl River Delta region of China. This region has attracted more and more attention for its fastest economy growth rate in the world and yet the accompanied severe air pollution. Whatever measurements are taken, the atmospheric conditions are found to be deteriorating. The development of remote sensing technology provides more dynamic and thorough observations of the environment beyond traditional methods. By using of systematic techniques including the ground-based lidar, sun-sky radiometer and satellite observations, we have continuously observed and investigated the local atmospheric aerosols. It would be our great pleasure that our research could help understand, mitigate and control the urgent environmental problems.