The Psychologic Effects from Breathing Air at 4 Atmospheres Pressure*

Air at high barometric pressures produces a narcotic effect on man. The changes which first appear at 3 atmospheres pressure are expressed in alterations of behavior, slowed mental activity, and impaired neuromuscular coordination. These effects, although previously observed, have not been attributed to the direct action of air or of the component gases, oxygen, nitrogen3 and carbon dioxide. Hill and Phillips (1932) reported that some of the deep sea divers (at depths of 270 to 300 feet, or 9 to 10 atmospheres absolute) had difficulty in assimilating facts and in making quick decisions, summarized as “a slowing of the process of cerebration.” Severe emotional disturbances were sometimes observed and loss of consciousness reported. The men affected in this manner were regarded as psychologically unstable. Damant (3 930) with reference to the paper of Hill and Phillips mentioned the “subtle change in character and behavior which comes over some men at less high air pressures,” and considered that either the increased oxygen tension or impurities in the air might be responsible. Hill, according to Damant, excluded oxygen and carbon dioxide as etiologic factors. Because of the many abnormal factors in the environment of the deep sea diver, the conclusion could not be drawn that changes in behavior and mental activity were caused by increased air pressure alone. It was of interest, therefore, to make observations on persons who were subjected to high air pressures in surroundings that were otherwise normal. This paper presents a description of the psychic changes in air at 4 atmospheres, and the inference is drawn that the increased partial pressure of nitrogen is mainly responsible for the abnormal responses. The observations were made in a large, well lighted pressure chamber described by Thomson, Yaglou and Van Woert (1932), on nine persons engaged in physiologic research under ordinary laboratory conditions except that the barometric pressure was raised from 1 to 4 atmospheres.