1 Tobacco Medicine and Tobacco Cessation Center, Center of Respiratory Medicine, China-Japan Friendship Hospital, Beijing, China; WHO Collaborating Center for Tobacco Cessation and Respiratory Diseases Prevention, Beijing, China; National Clinical Research Center for Respiratory Diseases, Beijing, China; Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100029, China; Department of Respiratory Medicine, Capital Medical University, Beijing, China.
2 Department of Pulmonary and Critical Care Medicine, Center of Respiratory Medicine, China-Japan Friendship Hospital, Beijing, China; WHO Collaborating Center for Tobacco Cessation and Respiratory Diseases Prevention, Beijing, China; National Clinical Research Center for Respiratory Diseases, Beijing, China; Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100029, China; Department of Respiratory Medicine, Capital Medical University, Beijing, China. Electronic address: wangchen@pumc.edu.cn.