Carbon dioxide gas is colourless and odourless gas or extremely cold liquid under pressure or refrigeration. It will not burn. Carbon dioxide is a compressed gas. It can displace oxygen in air and may accumulate in low areas which can be a confined space hazard. Carbon dioxide is a very mild central nervous system tranquilizer. Very high concentrations may cause headache, nausea, dizziness, sweating, restlessness and disorientation. Liquefied gas may cause frostbite.