Dr. Richard Vann has spent a career in environmental physiology or operational diving with particular emphasis on understanding the physiology of decompression sickness (DCS) and on developing procedures to avoid DCS. Beginning at Ocean Systems in 1967, he served as a Diving Engineer where, among other duties, he learned to compute decompression tables and acted as an experimental subject for dives to 650 feet. This was followed by four years in the Navy, two of these as the Diving Officer for Underwater Demolition 12. After receiving a Ph.D. in Biomedical Engineering at Duke in 1976, he joined the faculty at the Duke Center for Diving Medicine and Environmental Physiology where he conducted experiments to investigate bubble formation and inert gas exchange and developed decompression tables for scientific diving. In 1986, he began studies for NASA to investigate the use of exercise and other factors for accelerating nitrogen washout during oxygen pre-breathing prior to decompression to space suit pressure. These studies culminated in 1996 with an investigation of how simulated microgravity affects DCS risk. This work and the results of the exercise experiments became part of the foundation for the Pre-breathe Reduction Program that led to the successful two hour decompression procedure presently used for extravehicular activity on the Space Station.