Oxygen deficiency hazards associated with liquefied gas systems: derivation of a program of controls.

The use of liquefied gases in industry and research has become commonplace. Release into the atmosphere of these gases will result in a displacement of air and a reduction in the oxygen concentration. Exposure to reduced levels of oxygen may cause reduced abilities, unconsciousness or death. This paper describes the derivation of a novel program of controls for oxygen deficiency hazards. The key to this approach is a quantitative assessment of risk for each planned operation and the application of control measures to reduce that risk to an acceptable level. Five risk levels evolve which are based on the probability of fatality. Controls such as training, oxygen monitoring equipment, self-rescue respirators and medical surveillance are required when the probability of fatality exceeds 10(-7) per hour. The quantitative nature of this program ensures an appropriate level of control without undue burden or expense.