1. Department of Safety Engineering, China Institute of Industrial Relations, Beijing, China
2. Department of Environmental Health (Environmental and Occupational Medicine and Epidemiology Program), Harvard School of Public Health, Boston, Massachusetts, USA
3. Shanghai Putuo District People’s Hospital, Shanghai, China
4. School of Public Health, University of California Berkeley, Berkeley, California, USA
5. Pulmonary and Critical Care Unit, Massachusetts General Hospital, and Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA