When I worked at the W. M. Keck Observatory on the 13,796 feet very high altitude summit of Mauna Kea, we would routinely be engulfed in cold clouds of helium and nitrogen gas as we discharged it into...
Astronomy staff that routinely discharged industrial gas into the indoor environment at high altitudes did not wear oxygen deficiency monitors or protective breathing respirators.
(imp. & p. p.) of Discharge
When I worked in astronomy, I routinely observed young college and university students working with liquid nitrogen and breathing nitrogen gas as they discharged it into the indoor environment at high...