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Chapter 43
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OXYGEN PRESSURE
1. CNS AND RESP. TOXICITY
2. EFFECT ON RECOMPRESSION THERAPY
3. ? NITROGEN NARCOSIS & DCS
4. MIXING & HANDLING DANGER
5. HYPOXIC MIXTURES
6. CO2 BUILD UP
7. EQUIPMENT CHANGES
There is little concern about oxygen toxicity when diving with compressed air within recreational
diving limits. Neurological and respiratory oxygen toxicity are virtually impossible. Also, the
amount of oxygen exposure is unlikely to significantly influence any recompression treatments that
may be needed for decompression accidents. Neither statement can be applied to technical diving.
It had been assumed that oxygen, by virtue of its replacement of nitrogen, would to some degree
reduce the severity of nitrogen narcosis and decompression sickness. Although this is possibly so
in theory, the scant experimental evidence that there is available, would suggest that oxygen may
actually contribute to nitrogen narcosis. The possibility that O2 could contribute to DCS has been
proposed, but this is unproven.
Inadequate mixing can result in oxygen pressures being higher or lower than intended. This has
implications regarding the safety of the dive profile.
Higher oxygen levels are also likely to interfere with carbon dioxide transport in the blood. This
has implications as regards carbon dioxide and oxygen toxicity, nitrogen narcosis and possibly
decompression sickness.
The handling of gas mixtures, where oxygen is used or is added to air or other gases, can produce
some hazards. Oxygen increases the risk of fire and explosion.
Some divers have observed that O2 aggravates the deterioration of soft materials, such as O-rings
and other materials that comprise the diving equipment. It can also accelerate corrosion in
cylinders.
See The Technical Dive, above.