A study of unusual incidents in a well-documented series of dives

We have analysed 43 unusual incidents, which occurred, during 1303 well-documented dives, according to the environmental factors involved. The objective was to find some indication of the causes of otherwise unexplained loss of consciousness in working divers. It was concluded that rapid compression may handicap divers if adequate time for recovery is not allowed in those adversely affected. Air diving deeper than 48 m (160 ft) appears to be unduly hazardous. A significant proportion of incidents studied may result from an interaction between the physiological effects of oxygen and carbon dioxide, especially in periods of hard work. The possibility was also raised that pressure alone might adversely lower acute oxygen toxicity thresholds. Diving with a Po2 below 1.3 bar prevents acute oxygen toxicity, while a Po2 exceeding 1.6 bar is potentially hazardous.