He received his M.D. in 1983 from Nanjing Medical University, an M.P.H. in Environmental Health Sciences in 1987 from Peking University School of Public Health, an M.S. in Environmental Health in 1994 and a Sc.D. in Industrial Hygiene in 1997, both from the Harvard School of Public Health. Dr. Liu’s expertise is in exposure assessment and modeling, indoor air sciences, industrial hygiene, and occupational epidemiology, with considerable expertise in respirator fit testing and respirator workplace performance evaluation.