> Mercury and Gemini both had used pure oxygen environments with obviously no mishaps. Pure oxygen atmosphere is pretty dangerous. I worked with it at a steel

> Mercury and Gemini both had used pure oxygen environments with obviously no mishaps. Pure oxygen atmosphere is pretty dangerous. I worked with it at a steel mill where it was a process gas. Oxygen lines had to be "oxygen clean" before put into service. This meant no oil or grease or particulates that could strike a spark if propelled along the line. Also the line had to be sized for a maximum flow velocity or the oxygen would "scarf" the line. Think rapid oxidation like combustion. I read a fatality report where a pipe fitter descended into an oxygen valve pit and burst into flames. The report speculated that the fitter had some grease on his gloves that spontaneously combusted in the presence of pure oxygen. I suppose it's less hazardous at reduced pressure, but still not an atmosphere I would want to work in. A search finds more info at https://www.eiga.eu/uploads/documents/DOC013.pdf https://www.eiga.eu/uploads/documents/DOC013.pdf which discusses this.