Cryogenic fluids (cryogens) exhibit extremely low boiling-point temperatures (at atmospheric pressures), typically less than 170°K (-154°F/-103°C). These include liquefied atmospheric gases such as nitrogen and oxygen, along with argon, neon, hydrogen and helium. At room temperature, Carbon Dioxide is typically stored as a liquid under pressure (approximately 700 psi).
Small cryogenic storage devices (dewars) in laboratories are typically designed to be vented to atmosphere. If pressure is allowed to build up due to a blockage in its vent system (typically from contamination), the dewar is considered plugged and could cause an explosion due to the expansion of liquid to gas.