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Liquid Nitrogen
One of the big advantages of liquid nitrogen is that nothing extra is needed to produce fog. Liquid nitrogen works by evaporating and by cooling the air, causing water to condense. Nitrogen is the primary component of air and is non-toxic.
Important Points
- Nitrogen fog sinks to the ground.
 - Smoke can be made by either letting the nitrogen off-gas naturally or by using a fan to blow the 'smoke' where it is wanted.
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- Liquid nitrogen presents a serious hazard to the user. Although dry ice can give you frostbite, liquid nitrogen is cold enough to cause considerable tissue damage and death. Do not use nitrogen unless you have had the proper cryogenics training. Never use liquid nitrogen in a situation where other people can access the nitrogen source.
 - As the nitrogen concentration increases, the oxygen concentration in a room decreases, presenting a potential asphyxiation hazard.
Most smoke machines use water with a glycol mixture to produce special effects. To find out how this is done, continue on to Atomized Glycols.