Frank Speizer, MD, is the founding Principal Investigator (PI) of the NHS. He remained in the PI role through 2000 and is currently a Senior Investigator with the Study. He is the Edward H. Kass Distinguished Professor of Medicine at Harvard Medical School and Professor of Environmental Science at the Harvard T.H. Chan School of Public Health. Dr. Speizer’s major research interests include chronic disease epidemiology, with a specific focus on respiratory and cardiovascular diseases and cancers in women, and health effects of air pollution.