1 Department of Respiratory and Critical Care Medicine, Chronic Airways Diseases Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, China.
2 Department of Allergy and Clinical Immunology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong 510120, China.
3 Department of Occupational Health and Occupational Medicine School of Public Health, Southern Medical University, Guangzhou, Guangdong 510515, China.