Prolonged breathing of extremely cold air may damage the lungs. When cryogenic liquids form a gas, the gas is very cold and usually heavier than air. This cold, heavy gas does not disperse very well and can accumulate near the floor. Even if the gas is non-toxic, it displaces air. When there is not enough air or oxygen, asphyxiation and death can occur.
Oxygen deficiency is a serious hazard in enclosed or confined spaces.
Small amounts of liquid can evaporate into very large volumes of gas. Each gas can cause specific health effects. For example, liquid carbon monoxide can release large quantities of carbon monoxide gas, which can cause death almost immediately. Refer to the material safety data sheet for information about the toxic hazards of a particular cryogen. Fire Hazard Flammable gases such as hydrogen, methane, liquefied natural gas and carbon monoxide can burn or explode.