Editing Decompression sickness (section)

=== Ascent from depth ===
DCS is best known as a [[diving disorder]] that affects divers having breathed gas that is at a higher pressure than the surface pressure, owing to the pressure of the surrounding water. The risk of DCS increases when diving for extended periods or at greater depth, without ascending gradually and making the [[decompression stops]] needed to slowly reduce the excess pressure of inert gases dissolved in the body. The specific risk factors are not well understood and some divers may be more susceptible than others under identical conditions.{{r|38uhms | Benton}} DCS has been confirmed in rare cases of [[apnea|breath-holding]] divers who have made a sequence of many deep dives with short surface intervals, and may be the cause of the disease called [[taravana]] by South Pacific island natives who for centuries have dived by breath-holding for food and [[pearl]]s.{{r|Wong1999}}

Two principal factors control the risk of a diver developing DCS:

# the rate and duration of gas absorption under pressure&nbsp;– the deeper or longer the dive the more gas is absorbed into body tissue in higher concentrations than normal ([[Henry's Law]]);
# the rate and duration of outgassing on depressurization&nbsp;– the faster the ascent and the shorter the interval between dives the less time there is for absorbed gas to be offloaded safely through the lungs, causing these gases to come out of solution and form "micro bubbles" in the blood.{{sfn|Lippmann & Mitchell|pp=65–66}}

Even when the change in pressure causes no immediate symptoms, rapid pressure change can cause permanent [[bone]] injury called [[dysbaric osteonecrosis]] (DON). DON can develop from a single exposure to rapid decompression.{{r|Ohta1974}}