1 West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China; International Institute of Spatial Lifecourse Epidemiology (ISLE), Hong Kong, China.
2 Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Hong Kong, China; International Institute of Spatial Lifecourse Epidemiology (ISLE), Hong Kong, China. Electronic address: jiapengff@hotmail.com.