Probability of oxygen toxicity using an 8 psi space suit

Breathing oxygen at high partial pressure is toxic to all systems of the body. However, the effect a of a high PO2 on the pulmonary and erythropoietic systems pose the greatest threat to the EVA astronaut utilizing a single gas space suit system. Oxygen toxicity has been studied extensively, and a review of the literature suggests that continuous exposure to a PO2 of 8 psi can be tolerated indefinitely and should not present the astronaut with a problem for the Extravehicular Activity (EVA) scenarios projected for Space Station. However, the cause of the decrease in circulating red blood cell mass, which has been shown to accompany exposure to microgravity as well as hyperoxemia, is not as well defined when both conditions are simultaneously present.