1. Research Center for Occupational Respiratory Diseases, West China School of Public Health (No. 4 West China Teaching Hospital), Sichuan University, 16#, Section 3, Renmin Road South, Chengdu, 610041 Sichuan, China
2. Chengdu Center for Disease Control and Prevention, 4#, Longxiang Road, Chengdu, 610041 Sichuan, China
3. Department of Public Health Laboratory Sciences, West China School of Public Health (No. 4 West China Teaching Hospital), Sichuan University, 16#, Section 3, Renmin Road South, Chengdu, 610041 Sichuan, China
4. Sichuan Center for Disease Control and Prevention, 16#, Xiaoxue Road, Chengdu, 610041 Sichuan, China