Liquid nitrogen undergoes sublimation in room temperature which rapidly expands in volume. This extra volume of gaseous nitrogen quickly displaces air, making the enviornment anoxic and deadly to aerobic organisms, like humans. Nitrogen intoxication is painless and asymptomatic until you start to feel light-headed and dizzy, which is by all means, lethal, unless proper treatment is given immediately. Those suffering from lack of oxygen should be given fresh air. If victim is not breathing, artificial breathing may be required. If breathing is difficult, administer pure oxygen.
In laboratories where liquid nitrogen is used to store cells, they are always kept sealed in dewar tanks and never left opened for longer than 5 minutes. Oxygen sensors should be fitted to prevent accidental poisoning.
Extra precaution should be taken when transporting liquid nitrogen in elevators. If the tank becomes toppled and liquid nitrogen escapes, get out of the elevator as fast as possible.
Last but not least, always wear thermoprotection gloves when coming into close contact with liquid nitrogen. It is VERY cold... -196C!!!
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