Dry ice or liquid nitrogen. It is more likely to be liquid nitrogen, which is liquid nitrogen, colorless, odorless, non-corrosive, non-flammable and extremely low in temperature. Actually, it's not "smoke", but "water vapor"-the temperature of this product is-0/96 degrees. When it comes into contact with air containing moisture at room temperature, it will condense water molecules and form water vapor, which becomes a scene of "dust flying".