On October 20th to 24th, Prof. Tang Xiaoyan (Member of the Chinese Academy of Sciences) and Prof. Zhu Tong led the delegation of College of Environmental Sciences and Engineering, Peking University to visit to Hong Kong and Macau. The delegation visited Environment Bureau, Hong Kong; Environmental Protection Bureau, Macau; City University of Hong Kong; the University of Hong Kong; the Hong Kong Polytechnic University and the Hong Kong University of Science and Technology. The delegation also held the "Clean Air: the responsibility of government, enterprise, universities and society" Cultural Salon.