The truth is, liquid nitrogen is completely inert except for its extreme temperature.It will cause any metal it comes in contact with to become freezing cold, but wearing dry gloves is enough to protect your hands.The liquid nitrogen itself will evaporate before it contacts your skin due to the Leidenfrost effect.
Suffocation: If person seems to become dizzy or looses conciousness while working with liquid nitrogen, move to a well-ventilated area immediately. If breathing has stopped, apply artificial respiration.Call a physician.Keep warm and at rest.
Frost bite: If exposed to liquid or cold gas, restore tissue to normal body temperature, 98.6F (37C), followed by protection of the injured tissue from further damage and infection.Remove or loosen clothing that may constrict blood circulation to the frozen area.Rapid warming of the affected part is best achieved by using water at 106F (42C).
Under no circumstances should the water be over 112F (44C), nor should the frozen part be rubbed either before or after rewarming.The patient should neither smoke.