An open flask of industrial liquid gas that is venting into the indoor environment should be thought of as the same as a smoldering fire, as they both create a dangerous oxygen deficient environment for the human.

Industrial liquid gas containers were left open and venting gas into the indoor environment in high altitude astronomy. On reflection, I realized that I routinely observed mental and physical effects that match those of a low oxygen environment in staff that I supervised.

When discharging industrial gas into the indoor environment in high altitude astronomy, we never wore breathing respirators that fed us oxygenated air at above the legally required 19.5% oxygen levels.

The toxicity of medical and industrial gas to the human depends on where it is used. A gas that is regarded as safe in a well ventilated environment at sea level may be a toxic gas in an indoor environment at high altitude.

Astronomy staff that routinely discharged industrial gas into the indoor environment at high altitudes did not wear oxygen deficiency monitors or protective breathing respirators.

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.