Stephen Kales

Stefanos Kales

Associate Professor in the Department of Environmental Health

Department of Environmental Health

Cambridge Hospital
Macht Building 427
1493 Cambridge Street
Cambridge, MA 02139
Phone: 617.665.1580


Stefanos N. Kales, MD, MPH, FACP, FACOEM, is an Associate Professor of Medicine at Harvard Medical School, and Associate Professor and Director of the Occupational and Environmental Medicine Residency at the Harvard School of Public Health (HSPH). He is Board Certified in Preventive Medicine: Occupational Medicine, and has been elected to Fellowship by both the American College of Physicians and the American College of Occupational & Environmental Medicine. Dr. Kales is the Chief of Occupational and Environmental Medicine and Medical Director for Employee Health and Industrial Medicine at the Cambridge Health Alliance, a Harvard-affiliated hospital system. He is also an occupational medicine consultant to the Massachusetts/Rhode Island Poison Control Center.

Dr. Kales has participated in a wide range of research, advisory, and teaching activities on five continents resulting in over 100 publications and wide recognition nationally and internationally. He also serves on the editorial boards of the Archives of Environmental and Occupational Health and BMC Public Health, and on the international advisory board of Occupational Medicine, London.

Residency Director

In 2006, Dr. Kales was selected to lead the Occupational and Environmental Medicine Residency at HSPH. This program is Harvard’s only preventive medicine residency, and the premier Occupational Medicine program in the US. Since 2006, Harvard OEM trainees have received 17 national awards. Innovations implemented under his leadership include the Initiative for Productivity and Health Management to maximize workforce health to the benefit of both employees and their employers, and a Complementary Pathway for training mid-career Occupational Medicine professionals.

Research Interests

Dr. Kales’ primary research involves the health of firefighters and police officers, and he is an international clinical authority regarding cardiovascular disease among public safety personnel. His fire service research has received Massachusetts, Federal (NIOSH and FEMA R&D grants), and Canadian funding. With significant expertise on obesity and cardio-metabolic risk factors in general, he collaborates with other scientific groups on the interfaces between the workplace and metabolic health effects. Dr. Kales’ work has been most influential in determining the causal relationship of heart disease among firefighters to their job activities and other factors. His group has provided seminal contributions in the clinical epidemiology of cardiovascular events in firefighters, including the first definitive statistical association of strenuous job tasks and on-duty cardiovascular deaths, which was subsequently confirmed in a later New England Journal of Medicine publication. Click here to learn more about this ongoing research.

Dr. Kales is also a leader in the emerging field of occupational sleep medicine. He was among the first occupational medicine directors to institute an objective OSA screening protocol for commercial drivers in a busy clinic dealing with driver medical certifications. His group is currently examining psychomotor vigilance testing and driving simulation in relationship to BMI and adiposity and OSA as potential “in clinic” tools for detecting fatigue/sleep disorders in the occupational health setting. Dr. Kales has also lectured at regional, national, and international meetings on OSA screening from the standpoint of occupational health.

Due to Dr. Kales’ research efforts, he participates in Harvard School of Public Health’s Cardiovascular Epidemiology Program and Harvard Medical School’s Division of Sleep Medicine. In April 2013, he was presented the Kehoe Award for Excellence in Education and Research in Occupational and Environmental Medicine by the American College of Occupational and Environmental Medicine (ACOEM) for his leadership in and contributions to the field of OEM.

Clinical Work

Dr. Kales’ hospital division coordinates occupational health services for over 4,000 Cambridge Health Alliance employees and external clients. The latter have rapidly grown under his leadership from 60 to over 500 client companies. They provide high quality care to injured workers; maintain workers’ compensation costs below the industry benchmark; determine the ability of employees with illness and/or impairment to engage in safety-sensitive functions; and provide expert consultation to human resources and senior administration. They are also an internationally recognized center for clinical training and research in occupational medicine.


As a result of his reputation, Dr. Kales is frequently consulted by government agencies, colleagues, insurers, employers, and legal professionals throughout North America and beyond regarding a wide variety of occupational and environmental medicine issues. An active Occupational Medicine practitioner, researcher, and educator, Dr. Kales seeks to develop further the HSPH OEMR’s tradition of rigorous training, research excellence, and diverse practicum opportunities. His primary goal is to ensure that graduates are prepared for whatever potential career option they choose, whether in healthcare, academia, corporate medicine, public service, or consulting.


BS, 1985 Bucknell University
MD, 1989 Harvard Medical School
MPH, 1992 Harvard School of Public Health

Other Affiliations

Associate Professor of Medicine, Harvard Medical School
Director, Occupational and Environmental Medicine Residency, Harvard School of Public Health
Division Chief, Occupational and Environmental Medicine, The Cambridge Health Alliance