Nitrogen-Oxygen Mixture Physiology, Phases 1 and 2

By measurement of respiratory variables and carbon dioxide levels, exposure to nitrogen oxygen mixtures at depth during exertion was found to result in carbon dioxide levels well above these encountered in other conditions. Some individuals showed levels consistent with symptoms of carbon dioxide intoxication, although few actual symptoms related either to oxygen poisoning or to carbon dioxide excess were reported. The results suggest, but do not conclusively show, a definite relationship between symptoms and carbon dioxide levels. The results strongly indicate that individuals tending to show high carbon dioxide levels do not fall into a discrete group. At present, personnel selection does not appear promising for extension of nitrogen oxygen diving limits.