“During my time in high altitude astronomy, I routinely witnessed workers breathing medical oxygen, industrial carbon dioxide, nitrogen and helium gas as part of their daily work routine.”

tags: altitude, astrobiology, astronomer, astronomical, astronomy, astrophysics, astrosociobiology, breathing, carbon, daily, dioxide, during, gas, helium, high, industrial, liquid, medical, nitrogen, osha, oxygen, routine, time, witnessed, work, workers