Survival Differences Breathing Air and Oxygen at Equivalent Altitudes. * †

Abstract

Summary

Mice were exposed progressively to equivalent degrees of hypoxia breathing air and breathing 100% O₂. The inspired pO₂ level at which unconsciousness set in was found to be significantly lower when air was breathed than when 100% oxygen was breathed provided the rate of ascent was 2 × 10³ ft/min or greater. This advantage of air over oxygen is attributed to the transient “N₂ dilution” or R.Q. effect.