"Oxygen-enriched environments exist in a variety of places, sometimes where they may not seem obvious. Oxygen enrichment is often the result of leaks from damaged or poorly maintained equipment; leaks from poor connections; opening valves deliberately or accidentally using an excess of oxygen in welding, flame cutting or a similar process; or poor ventilation where oxygen is being used. This photograph illustrates the interior of a recompression or hyperbaric chamber found in a community hospital. Hyperbaric chambers are vessels in which a high-pressure environment is used primarily to treat decompression sickness, gas embolism, carbon monoxide poisoning, gas gangrene resulting from infection by anaerobic bacteria, tissue injury arising from radiation therapy for cancer, and wounds that are difficult to heal."
Coffee Break Training - Fire Protection Series No. FP-2014-12
United States Fire Administration: http://www.usfa.fema.gov/