Cryogenic liquids can pose an asphyxiation hazard due to which condition in enclosed spaces?

• A. Oxygen displacement reducing ambient oxygen
• B. Increased oxygen levels causing fire hazard
• C. Instant combustion of surrounding air
• D. No atmospheric effect

Answer: (A)

Cryogenic liquids create an asphyxiation hazard because they boil off into gas that rapidly displaces the ambient air in an enclosed space. That cold, expanding gas reduces the concentration of breathable oxygen, so anyone in the area can become oxygen-deficient even if there is plenty of air in the room overall. In poorly ventilated spaces, this displacement can happen quickly enough to cause dizziness, disorientation, or loss of consciousness before distress is noticed. The danger is not from increased oxygen or instant combustion of the air; the gas simply lowers the amount of oxygen available for breathing, and may pool near the floor where it’s easier to inhale from breathing zones.