Editing Decompression sickness (section)

=== Environmental ===
The following environmental factors have been shown to increase the risk of DCS:

* the magnitude of the pressure reduction ratio&nbsp;– a large pressure reduction ratio is more likely to cause DCS than a small one.{{r|Dehart | Vann1 | Fryer}}
* repetitive exposures&nbsp;– repetitive dives within a short period of time (a few hours) increase the risk of developing DCS. Repetitive ascents to altitudes above {{convert|5500|m|ft}} within similar short periods increase the risk of developing altitude DCS.{{r|Dehart | Fryer}}
* the rate of ascent&nbsp;– the faster the ascent the greater the risk of developing DCS. The ''[[U.S. Navy Diving Manual]]'' indicates that ascent rates greater than about {{convert|20|m/min|ft/min||abbr=on}} when diving increase the chance of DCS, while recreational dive tables such as the [[Bühlmann tables]] require an ascent rate of {{convert|10|m/min|ft/min||abbr=on}} with the last {{convert|6|m|ft||abbr=on}} taking at least one minute.{{sfn|Lippmann & Mitchell|p=232}} <!-- There are some doppler bubble studies to support this --> An individual exposed to a rapid decompression (high rate of ascent) above {{convert|5500|m|ft}} has a greater risk of altitude DCS than being exposed to the same altitude but at a lower rate of ascent.{{r|Dehart | Fryer}}
* the duration of exposure&nbsp;– the longer the duration of the dive, the greater is the risk of DCS. Longer flights, especially to altitudes of {{convert|5500|m|ft|abbr=on}} and above, carry a greater risk of altitude DCS.{{r|Dehart}}
* underwater diving before flying&nbsp;– divers who ascend to altitude soon after a dive increase their risk of developing DCS even if the dive itself was within the dive table safe limits. Dive tables make provisions for post-dive time at surface level before flying to allow any residual excess nitrogen to outgas. However, the pressure maintained inside even a pressurized aircraft may be as low as the pressure equivalent to an altitude of {{convert|2400|m|ft|abbr=on}} above sea level. Therefore, the assumption that the dive table surface interval occurs at normal atmospheric pressure is invalidated by flying during that surface interval, and an otherwise-safe dive may then exceed the dive table limits.{{r|Bassett | FAD | pmid17672177}}
* diving before travelling to altitude&nbsp;– DCS can occur without flying if the person moves to a high-altitude location on land immediately after diving, for example, scuba divers in [[Eritrea]] who drive from the coast to the [[Asmara]] plateau at {{convert|2400|m|ft|abbr=on}} increase their risk of DCS.{{sfn|Lippmann & Mitchell|p=79}}
* [[Altitude diving|diving at altitude]]&nbsp;– diving in water whose surface pressure is significantly below sea level pressure – for example, [[Lake Titicaca]] is at {{convert|3800|m|ft|abbr=on}}. Versions of [[decompression table]]s for altitudes exceeding {{convert|300|m|ft|abbr=on}}, or [[dive computer]]s with high-altitude settings or surface pressure sensors may be used to reduce this risk.{{r|Bassett | Egi}}