Uncontrolled decompression: Difference between revisions

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This [[Urban legend|persistent myth]] is based on a failure to distinguish between two types of decompression and their exaggerated portrayal in some [[fiction|fictional works]]. The first type of decompression deals with changing from normal atmospheric pressure (one [[Atmosphere (unit)|atmosphere]]) to a vacuum (zero atmosphere) which is usually centered around [[space exploration]]. The second type of decompression changes from exceptionally high pressure (many atmospheres) to normal atmospheric pressure (one atmosphere) as may occur in [[deep-sea diving]].

The first type is more common as pressure reduction from normal atmospheric pressure to a vacuum can be found in both space exploration and high-altitude [[aviation]]. Research and experience have shown that while [[Effect of spaceflight on the human body#Space environments|exposure to a vacuum]] causes swelling, [[skin|human skin]] is tough enough to withstand the drop of one [[atmosphere (unit)|atmosphere]].<ref name="Barratt">{{cite web|url=http://www.uh.edu/engines/epi2691.htm|title=No. 2691 THE BODY AT VACUUM|work=www.uh.edu|author=Michael Barratt|access-date=April 19, 2018|author-link=Michael Barratt (astronaut)}}</ref><ref name="Kruszelnicki">{{cite web|url=http://www.abc.net.au/science/articles/2005/04/07/1320013.htm|title=Exploding Body in Vacuum|publisher=[[ABC News (Australia)]]|author=Karl Kruszelnicki|date=April 7, 2005|access-date=April 19, 2018|author-link=Karl Kruszelnicki}}</ref> The most serious risk from vacuum exposure is [[Hypoxia (medical)|hypoxia]], in which the body is starved of [[oxygen]], leading to unconsciousness within a few seconds.<ref name="FAA" >{{cite web|title=Advisory Circular 61-107 |url=http://www.faa.gov/pilots/training/airman_education/media/AC%2061-107A.pdf|pages=table 1.1|publisher=[[FAA]] }}</ref><ref>{{cite book|title=Flight Surgeon's Guide|chapter-url=http://wwwsam.brooks.af.mil/af/files/fsguide/HTML/Chapter_02.html|chapter=2|publisher=[[United States Air Force]]|url-status=dead|archive-url=https://web.archive.org/web/20070316011544/http://wwwsam.brooks.af.mil/af/files/fsguide/HTML/Chapter_02.html|archive-date=2007-03-16}}</ref> Rapid uncontrolled decompression can be much more dangerous than vacuum exposure itself. Even if the victim does not hold their breath, venting through the windpipe may be too slow to prevent the fatal rupture of the delicate [[Pulmonary alveolus|alveoli]] of the [[lung]]s.<ref name="harding">{{Cite book | last1=Harding | first1=Richard M. | year=1989 | title=Survival in Space: Medical Problems of Manned Spaceflight | place=London | publisher=Routledge | isbn=0-415-00253-2 | url=https://archive.org/details/survivalinspacem0000hard }}</ref> [[Eardrum]]s and sinuses may also be ruptured by rapid decompression, and soft tissues may be affected by bruises seeping blood. IfEven if the victim somehow survivessurvived, the stress and shock would accelerate oxygen consumption, leading to hypoxia at a rapid rate.<ref name=czarnik>{{cite web |author=Czarnik, Tamarack R. |year=1999 |title=Ebullism at 1 Million Feet: Surviving Rapid/Explosive Decompressionn |url=http://www.geoffreylandis.com/ebullism.html |access-date=2009-10-26 }}</ref> At the extremely low pressures encountered at altitudes above about {{convert|63000|ft|m|-3}}, the boiling point of water becomes less than normal body temperature.<ref name="Barratt"/> This measure of altitude is known as the [[Armstrong limit]], which is the practical limit to survivable altitude without pressurization. Fictional accounts of bodies exploding due to exposure from a vacuum include, among others, several incidents in the movie ''[[Outland (film)|Outland]]'', while in the movie ''[[Total Recall (1990 film)|Total Recall]]'', characters appear to suffer effects of [[ebullism]] and blood boiling when exposed to the [[atmosphere of Mars]].

The second type is rare since it involves a pressure drop over several atmospheres, which would require the person to have been placed in a pressure vessel. The only likely situation in which this might occur is during decompression after deep-sea diving. A pressure drop as small as 100 Torr (13 kPa), which produces no symptoms if it is gradual, may be fatal if it occurs suddenly.<ref name="harding" /> [[Byford Dolphin#Diving bell accident|One such incident]] occurred in 1983 in the [[North Sea]], where violent explosive decompression from nine atmospheres to one caused four divers to die instantly from massive and lethal [[barotrauma]].<ref>{{cite book|title=North Sea Divers – a Requiem|last=Limbrick|first=Jim|pages=168–170|___location=[[Hertford]]|publisher=Authors OnLine|year=2001|isbn=0-7552-0036-5|url=https://books.google.com/books?id=lPp68NAoUF0C&pg=PA168}}</ref> Dramatized fictional accounts of this include a scene from the film ''[[Licence to Kill]]'', when a character's head explodes after his [[diving chamber|hyperbaric chamber]] is rapidly depressurized, and another in the film ''[[DeepStar Six]]'', wherein rapid depressurization causes a character to [[hemorrhage]] profusely before exploding in a similar fashion.