Oxygen deficiency is considered among the most common and dangerous atmospheric hazards. Laboratories, production complexes, gas storage areas, medical facilities, food processing plants, grain elevators, welding facilities, etc. are installations where often significant amounts of inert gases such as nitrogen, argon, helium, carbon dioxide, etc. are used. A leak of any of these gases can pose a significant danger to personnel due to oxygen depletion. Fresh air contains 20.9% oxygen by volume and with that as a reference, OSHA considers breathing air to be oxygen deficient at 19.5%. Permanently installed oxygen deficiency monitors should be used as a first line of protection.