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NAUI Scuba Diver 118 Diving Science Note: All symptoms vary with di erent people and occur di erently at varying depths on each side. tanks must never be filled with pure oxygen. The percentage of oxygen in regular air is not toxic until well below to the sport-diving limit of 40 meters (130 feet). Some divers receive specialized training in the Surface 50 ft. 100 ft. 150 ft. 200 ft. 250 ft. use of special gas mixtures that have a percentage of oxygen and nitrogen different from the percentages in regular air. These mixtures are referred to as nitrox or enriched air (figure 4-34). Nitrox has other benefits, but because it has a higher percentage of oxygen than air, maximum dive depths are actually reduced. Using these gases requires special training. Ask your instructor about the NAUI Enriched Air Nitrox specialty courses in your area if you are interested in learning about diving with these gases. Carbon Monoxide Toxicity Carbon monoxide is a gas formed by the incomplete combustion usually of a petroleum product such as gasoline or oil. This gas is potentially dangerous even in small concentrations, especially when it is breathed under pressure. Carbon monoxide itself is colorless, odorless, and tasteless but air that has been contaminated with it might taste and smell oily or foul. Divers can encounter problems with carbon monoxide if exhaust fumes from a gasoline- or diesel-powered engine contaminate their air supply. This occurs when the intake for the compressor is placed too close to the exhaust for any engine, including the engine that drives the compressor. In this situation, gases from the engine exhaust are compressed along with the air. In addition, Inability to think clearly and make accurate judgements in some divers. Dizziness in some deivrs. Inability to communicate or perform simple motor or mental tasks. Average diver is more or less useless and becomes a safety menace. FIGURE 4-33. THE SYMPTOMS OF NITROGEN NARCOSIS CAN BE SIMILAR TO ALCOHOL INTOXICATION.


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