Uncontrolled decompression

File:Explosive Decompression Test System.gif

The term uncontrolled decompression here refers to the unplanned depressurisation of vessels that are occupied by people; for example, a pressurised aircraft cabin at high altitude, a spacecraft, or a hyperbaric chamber. For the catastrophic failure of other pressure vessels used to contain gas, liquids, or reactants under pressure, the term explosion is more commonly used, or other specialised terms such as BLEVE may apply to particular situations.

Decompression can occur due to structural failure of the pressure vessel, or failure of the compression system itself.{{cite web|publisher=Federal Aviation Administration |url=http://www.faa.gov/pilots/training/airman_education/media/ac%2061-107a.pdf|date=2007-07-15 |title=AC 61-107A – Operations of aircraft at altitudes above 25,000 feet msl and/or mach numbers (MMO) greater than .75|access-date=2008-07-29}}{{cite book |title=Fundamentals Of Aerospace Medicine: Translating Research Into Clinical Applications, 3rd Rev Ed.|last=Dehart|first=R. L.|author2=J. R. Davis |year=2002 |publisher=Lippincott Williams And Wilkins|location=United States|isbn=978-0-7817-2898-0|page=720}} The speed and violence of the decompression is affected by the size of the pressure vessel, the differential pressure between the inside and outside of the vessel, and the size of the leak hole.

The US Federal Aviation Administration recognizes three distinct types of decompression events in aircraft: explosive, rapid, and gradual decompression.

Explosive decompression occurs typically in less than 0.1 to 0.5 seconds, a change in cabin pressure faster than the lungs can decompress.{{cite book|title=Flight Training Handbook|url=https://books.google.com/books?id=ioRTAAAAMAAJ|year=1980|access-date=2007-07-28|publisher=U.S. Dept. of Transportation, Federal Aviation Administration, Flight Standards Service|page=250|author1=Flight Standards Service, United States|author2=Federal Aviation Agency, United States}} Normally, the time required to release air from the lungs without restrictions, such as masks, is 0.2 seconds. The risk of lung trauma is very high, as is the danger from any unsecured objects that can become projectiles because of the explosive force, which may be likened to a bomb detonation.

Immediately after an explosive decompression, a heavy fog may fill the aircraft cabin as the air cools, raising the relative humidity and causing sudden condensation.{{Cite PHAK|year=2016|chapter=7|pages=36}} Military pilots with oxygen masks must pressure-breathe, whereby the lungs fill with air when relaxed, and effort has to be exerted to expel the air again.{{cite web|url=http://aupress.au.af.mil/digital/pdf/book/brulle_engineering_space_age.pdf|title=Engineering the Space Age: A Rocket Scientist Remembers|author=Robert V. Brulle|date=2008-09-11|publisher=AU Press|archive-url=https://web.archive.org/web/20110928085032/http://aupress.au.af.mil/digital/pdf/book/brulle_engineering_space_age.pdf|archive-date=2011-09-28|access-date=2010-12-01}}

Rapid decompression typically takes more than 0.1 to 0.5 seconds, allowing the lungs to decompress more quickly than the cabin.{{cite book|url=https://books.google.com/books?id=3hMZAAAAIAAJ|title=The New Frontier: Man's Survival in the Sky|author=Kenneth Gabriel Williams|year=1959|access-date=2008-07-28|publisher=Thomas}} The risk of lung damage is still present, but significantly reduced compared with explosive decompression.

Slow, or gradual, decompression occurs slowly enough to go unnoticed and might only be detected by instruments.{{Cite web |url=http://www.faa.gov/pilotos/training/airman_education/media/ac%2061-107a.pdf |title=AC 61-107A - Operations of aircraft at altitud above 25,000 feet MSL and/or mach numbers (MMO) greater than .75 |date=July 15, 2007 |work=Federal Aviation Administration }} This type of decompression may also come about from a failure to pressurize the cabin as an aircraft climbs to altitude. An example of this is the 2005 Helios Airways Flight 522 crash, in which the maintenance service left the pressurization system in manual mode and the pilots did not check the pressurization system. As a result, they suffered a loss of consciousness (as well as most of the passengers and crew) due to hypoxia (lack of oxygen). The plane continued to fly due to the autopilot system and eventually crashed due to fuel exhaustion after leaving its flight path.

File:US Navy 091006-N-9001B-017 Hospital Corpsmen 2nd Class Kyle Carswell and Daniel Young monitor members of the 2009 class of NASA astronaut candidates for hypoxia in an altitude chamber.jpg]]

The following physical injuries may be associated with decompression incidents:

• Hypoxia is the most serious risk associated with decompression, especially as it may go undetected or incapacitate the aircrew.{{cite journal |vauthors=Bason R, Yacavone DW |title=Loss of cabin pressurization in U.S. Naval aircraft: 1969–90 |journal=Aviat Space Environ Med |volume=63 |issue=5 |pages=341–345 |date=May 1992 |pmid=1599378 }}{{cite journal |author=Brooks CJ |title=Loss of cabin pressure in Canadian Forces transport aircraft, 1963–1984 |journal=Aviat Space Environ Med |volume=58 |issue=3 |pages=268–275 |date=March 1987 |pmid=3579812 }}{{cite web|url=http://www.theairlinepilots.com/medical/decompressionandhypoxia.htm|title=Cabin Decompression and Hypoxia|author=Mark Wolff|publisher=theairlinepilots.com |access-date=2008-09-01|date=2006-01-06}}
• Barotrauma: an inability to equalize pressure in internal air spaces such as the middle ear or gastrointestinal tract, or more serious injury such as a burst lung.
• Decompression sickness.{{cite journal |author1=Robinson, RR |author2=Dervay, JP |author3=Conkin, J |title=An Evidenced-Based Approach for Estimating Decompression Sickness Risk in Aircraft Operations |journal=NASA STI Report Series |volume=NASA/TM—1999–209374 |url=http://ston.jsc.nasa.gov/collections/TRS/_techrep/TM-1999-209374.pdf |access-date=2008-09-01 |url-status=dead |archive-url=https://web.archive.org/web/20081030231947/http://ston.jsc.nasa.gov/collections/TRS/_techrep/TM-1999-209374.pdf |archive-date=2008-10-30 }}{{cite journal |author=Powell, MR |year=2002 |journal=Undersea Hyperb. Med. |volume=Supplement |issue=abstract |title=Decompression limits in commercial aircraft cabins with forced descent |url=http://archive.rubicon-foundation.org/1181 |access-date=2008-09-01 |archive-date=2011-08-11 |archive-url=https://web.archive.org/web/20110811173704/http://archive.rubicon-foundation.org/1181 |url-status=usurped }}
• Altitude sickness.
• Frostbite or hypothermia from exposure to freezing cold air at high altitude.{{Cite journal|last1=Daidzic|first1=Nihad E.|last2=Simones|first2=Matthew P.|date=March{{ndash}}April 2010|title=Aircraft Decompression with Installed Cockpit Security Door |url=https://doi.org/10.2514/1.41953|journal=Journal of Aircraft|volume=47|issue=2|pages=490–504|doi=10.2514/1.41953|quote=[A]t 40,000 ft (12,200 m), the International Standard Atmosphere (ISA) pressure is only about 18.8 kPa (2.73 psi), and the air temperatures are about −56.5{{nbsp}}°C (217{{nbsp}}K). The boiling temperature of water at this atmospheric pressure is about −59{{nbsp}}°C (332{{nbsp}}K). Above 63,000 ft or 19,200 m (Armstrong line), the ISA environmental pressure drops below 6.3 kPa (0.91 psi) and the boiling temperature of water reaches the normal human body temperature (about 37 C). Any prolonged exposure to such an environment could lead to ebullism, anoxia, and ultimate death, after several minutes. These are indeed very hostile conditions for human life.

|url-access=subscription}}

• Physical trauma caused by the violence of explosive decompression, which can turn people and loose objects into projectiles.

At least two confirmed cases have been documented of a person being blown through an airplane passenger window. The first occurred in 1973 when debris from an engine failure struck a window roughly midway in the fuselage. Despite efforts to pull the passenger back into the airplane, the occupant was forced entirely through the cabin window.{{cite web|last=Mondout |first=Patrick |title=Curious Crew Nearly Crashes DC-10 |url=http://www.super70s.com/Super70s/Tech/Aviation/Disasters/73-11-03%28National%29.asp |access-date=2010-11-21 |url-status=dead |archive-url=https://web.archive.org/web/20110408023924/http://www.super70s.com:80/super70s/tech/aviation/disasters/73-11-03(National).asp |archive-date=2011-04-08 }} The passenger's skeletal remains were eventually found by a construction crew, and were positively identified two years later.{{cite news |last=Harden |first=Paul |title=Aircraft Down |url=http://www.dchieftain.com/news/aircraft-down/article_23a78c5b-7d34-5684-89ee-0f0a5de0c513.html |access-date=2018-10-24 |newspaper=El Defensor Chieftain |date=2010-06-05 |archive-date=2019-10-17 |archive-url=https://web.archive.org/web/20191017132530/http://www.dchieftain.com/news/aircraft-down/article_23a78c5b-7d34-5684-89ee-0f0a5de0c513.html |url-status=dead }} The second incident occurred on April 17, 2018, when a woman on Southwest Airlines Flight 1380 was partially blown through an airplane passenger window that had broken from a similar engine failure. Although the other passengers were able to pull her back inside, she later died from her injuries.{{cite web|url=https://www.foxnews.com/us/southwest-airlines-planes-engine-explodes-1-passenger-dead/|title=Southwest Airlines plane's engine explodes; 1 passenger dead|first=Kathleen|last=Joyce|website=Fox News|date=April 17, 2018}}{{Cite web|url=https://www.nbcphiladelphia.com/news/national-international/airplane-makes-emergency-landing-at-philadelphia-international-airport/52411/|title=Woman Partially Sucked Out of Jet When Window Breaks Mid-Flight; Plane Makes Emergency Landing in Philadelphia|first1=Vince|last1=Lattanzio|first2=Alicia Victoria|last2=Lozano|first3=Denise|last3=Nakano|first4=Brian X.|last4=McCrone • •|date=17 April 2018 }}{{cite news|last1=Stack|first1=Liam|last2=Stevens|first2=Matt|title=A Southwest Airlines Engine Explodes, Killing a Passenger|url=https://www.nytimes.com/2018/04/17/us/southwest-airlines-explosion.html|access-date=April 18, 2018|work=The New York Times|date=April 17, 2018}} In both incidents, the plane landed safely with the sole fatality being the person seated next to the window involved.

According to NASA scientist Geoffrey A. Landis, the effect depends on the size of the hole, which can be expanded by debris that is blown through it; "it would take about 100 seconds for pressure to equalise through a roughly {{convert|30.0|cm|in|abbr=on}} hole in the fuselage of a Boeing 747." Anyone blocking the hole would have half a ton of force pushing them towards it, but this force reduces rapidly with distance from the hole.{{cite web|url=http://www.news.com.au/travel/travel-updates/incidents/how-could-a-passenger-get-sucked-out-of-a-plane-and-has-it-happened-before/news-story/ce94c6632b6f485fbccb05dd64b9bbee|title=How could a passenger get sucked out of a plane – and has it happened before?|work=www.news.com.au|author=Lauren McMah|date=April 18, 2018|access-date=April 18, 2018}}

Modern aircraft are specifically designed with longitudinal and circumferential reinforcing ribs in order to prevent localised damage from tearing the whole fuselage open during a decompression incident.{{cite book|url=https://books.google.com/books?id=B3ng54W3sQ8C|pages=141–142|title=Beyond the Black Box|author=George Bibel|year=2007|isbn=978-0-8018-8631-7|access-date=2008-09-01|publisher=JHU Press}} However, decompression events have nevertheless proved fatal for aircraft in other ways. In 1974, explosive decompression onboard Turkish Airlines Flight 981 caused the floor to collapse, severing vital flight control cables in the process. The FAA issued an Airworthiness Directive the following year requiring manufacturers of wide-body aircraft to strengthen floors so that they could withstand the effects of in-flight decompression caused by an opening of up to {{convert|20|sqft|m2}} in the lower deck cargo compartment.{{cite web|url=http://www.faa.gov/about/media/b-chron.pdf|title=FAA Historical Chronology, 1926–1996|date=2005-02-18|access-date=2008-09-01|publisher=Federal Aviation Administration |archive-url = https://web.archive.org/web/20080624211236/http://www.faa.gov/about/media/b-chron.pdf |archive-date = 2008-06-24}} Manufacturers were able to comply with the Directive either by strengthening the floors and/or installing relief vents called "dado panels" between the passenger cabin and the cargo compartment.{{patent|US|6273365}}

Cabin doors are designed to prevent losing cabin pressure through them by making it nearly impossible to open them in flight, whether accidentally or intentionally. The plug door design ensures that when the pressure inside the cabin exceeds the pressure outside, the doors are forced shut and will not open until the pressure is equalized. Cabin doors, including the emergency exits, but not all cargo doors, open inwards, or must first be pulled inwards and then rotated before they can be pushed out through the door frame because at least one dimension of the door is larger than the door frame. Pressurization prevented the doors of Saudia Flight 163 from being opened on the ground after the aircraft made a successful emergency landing, resulting in the deaths of all 287{{nbs}}passengers and 14{{nbs}}crew members from fire and smoke.

Prior to 1996, approximately 6,000{{nbs}}large commercial transport airplanes were type certified to fly up to {{convert|45000|ft}}, without being required to meet special conditions related to flight at high altitude.{{Cite web|url=https://rgl.faa.gov/|title=RGL Home Page|website=rgl.faa.gov|access-date=2022-11-06|archive-date=2022-12-14|archive-url=https://web.archive.org/web/20221214143433/https://rgl.faa.gov/|url-status=dead}} In 1996, the FAA adopted Amendment 25–87, which imposed additional high-altitude cabin-pressure specifications, for new designs of aircraft types.{{cite web|url=http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/FED94F31539484AB852566720051AA5D?OpenDocument|title=Section 25.841: Airworthiness Standards: Transport Category Airplanes|publisher=Federal Aviation Administration|date=1996-05-07|access-date=2008-10-02|archive-date=2009-02-02|archive-url=https://web.archive.org/web/20090202140424/http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/FED94F31539484AB852566720051AA5D?OpenDocument|url-status=dead}} For aircraft certified to operate above 25,000 feet (FL 250; 7,600 m), it "must be designed so that occupants will not be exposed to cabin pressure altitudes in excess of {{convert|15000|ft}} after any probable failure condition in the pressurization system."{{Cite web|url=http://www.flightsimaviation.com/data/FARS/part_25-841.html|title=Flightsim Aviation Zone - Number 1 Flight Simulation & Aviation Resource! - Flight Simulator, Aviation Databases|website=www.flightsimaviation.com}} In the event of a decompression which results from "any failure condition not shown to be extremely improbable," the aircraft must be designed so that occupants will not be exposed to a cabin altitude exceeding {{convert|25000|ft}} for more than 2{{nbs}}minutes, nor exceeding an altitude of {{convert|40000|ft}} at any time. In practice, that new FAR amendment imposes an operational ceiling of 40,000{{nbs}}feet on the majority of newly designed commercial aircraft.{{cite web|url=http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgEX.nsf/0/9929ce16709cad0f8625713f00551e74/$FILE/8695.doc|title=Exemption No. 8695|publisher=Federal Aviation Administration|date=2006-03-24|location=Renton, Washington|access-date=2008-10-02|archive-date=2009-03-27|archive-url=https://web.archive.org/web/20090327094608/http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgEX.nsf/0/9929ce16709cad0f8625713f00551e74/$FILE/8695.doc|url-status=dead}}{{cite web|url=http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgPolicy.nsf/0/90AA20C2F35901D98625713F0056B1B8?OpenDocument|publisher=Federal Aviation Administration|date=2006-03-24|title=PS-ANM-03-112-16|access-date=2009-09-23|author=Steve Happenny}}{{efn|Notable exceptions include the Airbus A380, Boeing 787, and Concorde.}}

In 2004, Airbus successfully petitioned the FAA to allow cabin pressure of the A380 to reach {{convert|43000|ft}} in the event of a decompression incident and to exceed {{convert|40000|ft}} for one minute. This special exemption allows the A380 to operate at a higher altitude than other newly designed civilian aircraft, which have not yet been granted a similar exemption.

The Depressurization Exposure Integral (DEI) is a quantitative model that is used by the FAA to enforce compliance with decompression-related design directives. The model relies on the fact that the pressure that the subject is exposed to and the duration of that exposure are the two most important variables at play in a decompression event.{{cite web|url=http://mrcabinpressure.com/amd25-87.htm|title=Amendment 25–87|publisher=Federal Aviation Administration|access-date=2008-09-01}}

Other national and international standards for explosive decompression testing include:

• MIL-STD-810, 202
• RTCA/DO-160
• NORSOK M710
• API 17K and 17J
• NACE TM0192 and TM0297
• TOTALELFFINA SP TCS 142 Appendix H

Decompression incidents are not uncommon on military and civilian aircraft, with approximately 40–50 rapid decompression events occurring worldwide annually.{{cite web |url=http://www.amsanz.org.nz/avmedia/24/am24_2Decompression.pdf |title=Rapid Decompression In Air Transport Aircraft |date=2000-11-13 |access-date=2008-09-01 |publisher=Aviation Medical Society of Australia and New Zealand |url-status=dead |archive-url=https://web.archive.org/web/20100525193501/http://www.amsanz.org.nz/avmedia/24/am24_2Decompression.pdf |archive-date=2010-05-25 }} However, in most cases the problem is manageable, injuries or structural damage rare and the incident not considered notable.{{cite book|title=Air Quality in Airplane Cabins and Similar Enclosed Spaces |author1=Martin B. Hocking |author2=Diana Hocking |url=https://books.google.com/books?id=KzXPJ-p75QIC |isbn=3-540-25019-0|publisher=Springer Science & Business|year=2005|access-date=2008-09-01}} One notable, recent case was Southwest Airlines Flight 1380 in 2018, where an uncontained engine failure ruptured a window, causing a passenger to be partially blown out.{{cite web|url=https://news.sky.com/story/woman-sucked-from-southwest-airlines-plane-died-of-blunt-trauma-11337298|title=Woman sucked from Southwest Airlines plane died of 'blunt trauma'|website=Sky News}}

Decompression incidents do not occur solely in aircraft; the Byford Dolphin accident is an example of violent explosive decompression of a saturation diving system on an oil rig. A decompression event is often the result of a failure caused by another problem (such as an explosion or mid-air collision), but the decompression event may worsen the initial issue.

In 2004, the TV show MythBusters examined whether explosive decompression occurs when a bullet is fired through the fuselage of an airplane informally by way of several tests using a decommissioned pressurised DC-9. A single shot through the side or the window did not have any effect – it took actual explosives to cause explosive decompression – suggesting that the fuselage is designed to prevent people from being blown out.{{cite magazine|url=https://newsfeed.time.com/2011/04/05/southwests-scare-when-a-plane-decompresses-what-happens/|title=Southwest's Scare: When a Plane Decompresses, What Happens?|magazine=Time|author=Josh Sanburn|date=April 5, 2011|access-date=April 18, 2018}} Professional pilot David Lombardo states that a bullet hole would have no perceived effect on cabin pressure as the hole would be smaller than the opening of the aircraft's outflow valve.{{cite web|url=https://www.stuff.co.nz/travel/travel-troubles/103194084/the-deadly-result-when-a-large-hole-is-ripped-in-the-side-of-an-aircraft|title=The deadly result when a large hole is ripped in the side of an aircraft|work=www.stuff.co.nz|author=Michael Daly and Lorna Thornber|date=April 18, 2018|access-date=April 18, 2018}}

However, NASA scientist Geoffrey A. Landis points out that the impact depends on the size of the hole, which can be expanded by debris that is blown through it. Landis went on to say that "it would take about 100 seconds for pressure to equalise through a roughly {{convert|30.0|cm|in|abbr=on}} hole in the fuselage of a Boeing 747." He then stated that anyone sitting next to the hole would have about half a ton of force pulling them towards it.{{cite web|url=http://www.news.com.au/travel/travel-updates/incidents/how-could-a-passenger-get-sucked-out-of-a-plane-and-has-it-happened-before/news-story/ce94c6632b6f485fbccb05dd64b9bbee|title=How could a passenger get sucked out of a plane — and has it happened before?|work=www.news.com.au|author=Lauren McMah|date=April 18, 2018|access-date=April 18, 2018}} At least two confirmed cases have been documented of a person being blown through an airplane passenger window. The first occurred in 1973 when debris from an engine failure struck a window roughly midway in the fuselage. Despite efforts to pull the passenger back into the airplane, the occupant was forced entirely through the cabin window. The passenger's skeletal remains were eventually found by a construction crew, and were positively identified two years later. The second incident occurred on April 17, 2018, when a woman on Southwest Airlines Flight 1380 was partially blown through an airplane passenger window that had broken from a similar engine failure. Although the other passengers were able to pull her back inside, she later died from her injuries. In both incidents, the plane landed safely with the sole fatality being the person seated next to the window involved. Fictional accounts of this include a scene in Goldfinger, when James Bond kills the eponymous villain by blowing him out a passenger window{{cite web|url=http://news.bbc.co.uk/2/hi/uk_news/3039583.stm|title=Guns, Goldfinger and sky marshals|author=Ryan Dilley|publisher=BBC|quote=It's not all fiction. If an airliner's window was shattered, the person sitting beside it would either go out the hole or plug it - which would not be comfortable.|date=May 20, 2003}} and Die Another Day, when an errant gunshot shatters a window on a cargo plane and rapidly expands, causing multiple enemy officials, henchmen and the main villain to be sucked out to their deaths.

{{See also|Effect of spaceflight on the human body}}

This persistent myth is based on a failure to distinguish between two types of decompression and their exaggerated portrayal in some fictional works. The first type of decompression deals with changing from normal atmospheric pressure (one 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 exposure to a vacuum causes swelling, human skin is tough enough to withstand the drop of one atmosphere.{{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)}}{{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}} The most serious risk from vacuum exposure is hypoxia, in which the body is starved of oxygen, leading to unconsciousness within a few seconds.{{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 }}{{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}} 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 alveoli of the lungs.{{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 }} Eardrums and sinuses may also be ruptured by rapid decompression, and soft tissues may be affected by bruises seeping blood. If the victim somehow survived, the stress and shock would accelerate oxygen consumption, leading to hypoxia at a rapid rate.{{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 }} 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. 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, while in the movie 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. 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.{{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}} Dramatized fictional accounts of this include a scene from the film Licence to Kill, when a character's head explodes after his 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.

• {{annotated link|Decompression (altitude)}}
• {{annotated link|Decompression (diving)}}
• {{annotated link|Decompression (physics)}}
• {{annotated link|Time of useful consciousness}}

{{notelist}}

{{reflist|30em}}

• [http://www.geoffreylandis.com/vacuum.html Human Exposure to Vacuum]
• [http://www.urban-astronomer.com/articles/questions-and-answers/will-an-astronaut-explode-if-he-takes-off-his-helmet Will an astronaut explode if he takes off his helmet?]

{{Underwater diving|divsaf}}

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Category:Mechanical failure modes

Category:Aviation accidents and incidents

Category:Aviation medicine

Category:Underwater diving medicine