When transporting refrigerated liquefied cryogenic gases classified under Division 2.2 (such as Liquid Nitrogen UN 1977 or Liquid Argon UN 1951), what is the primary occupational health and safety hazard in an enclosed compartment or low-lying space?

1. Rapid asphyxiation (窒息) resulting from oxygen displacement as the cryogenic liquid vaporizes and expands hundreds of times in volume
2. Violent chemical polymerization releasing flammable hydrocarbon vapors
3. Spontaneous detonation caused by mechanical road vibration
4. Immediate bioaccumulation and systemic carcinogenicity upon skin contact