Prevention of hypoxia--acceptable compromises.

The acceptable degree of hypoxia is a most important factor in the design of pressure cabins and of aircrew oxygen breathing equipment. The studies of the effects of mild hypoxia upon human performance performed since 1960 are reviewed. It is concluded that the hypoxia induced by breathing air at altitudes up to 5000 ft is acceptable for both crew and passengers of combat and passenger aircraft. The magnitude and the effects of the hypoxia induced by rapid decompression are also considered. The results of the experimental investigations are correlated and it is deduced that the minimum acceptable alveolar oxygen tension on rapid decompression is 30 mm Hg.