[Lazamataz]

taffers claimed that the cylinder’s knob broke open when Maru was pulled in, causing it to leak. Maru inhaled an excessive amount of oxygen.

It takes days to die from oxygen poisoning.

Why did they leave him in there for days?

[Ozark Tom]

One source mentioned liquefied gas; but, failed to distinguish whether an oxygen or helium cryogen was the culprit.