Nitrogen asphyxiation

Nitrogen asphyxiation is an occasional cause of accidental death and a theoretical method of capital punishment advocated in a National Review article, "Killing with kindness – capital punishment by nitrogen asphyxiation" (Creque 1995). The painful experience of suffocation is not caused by lack of oxygen, but rather because of a buildup of carbon dioxide in the bloodstream which is exhaled under normal circumstances.

When humans breathe in pure nitrogen, they exhale carbon dioxide without resupplying oxygen. Nitrogen is a colorless, odorless and tasteless gas that constitutes approximately 78 percent of the Earth's atmosphere. As such, the subject would detect no abnormal sensation. This leads to asphyxiation without the painful and traumatic feeling of suffocation. Because of this property, nitrogen in Hebrew is called חנקן ("asphyxiator"); in German, "Stickstoff;" in Dutch, "stikstof;" ("suffocation matter") - the Scandinavian languages call it "kväve", "kvælstof" and "kvelstoff" from "kväva/kvele/kvæle" ("to asphyxiate"), in Greek, "άζωτο" ("not life-friendly"); in Russian and Serbian, "азот" (from the Greek word); in Croatian, "dušik" (from the word "dušiti", meaning "to asphyxiate");, in Japanese, 窒素 ("asphyxiation element"); and in Estonian, "lämmastik" (from "lämbuma", to suffocate).^{[citation needed]}

For this reason, accidental nitrogen asphyxiation is a possible hazard where large quantities of nitrogen are used. Also, deliberate nitrogen asphyxiation is viewed by some as a more humane way to end a human life in a controlled setting. As the principal component in air, nitrogen poses no significant risk upon discharge.

Nitrogen asphyxiation of animals in euthanasia

Hypoxic atmospheres have been used as methods of euthanasia in animals and as a means of slaughter in chickens (see controlled atmosphere killing). However, studies show that diving animals such as mink, and burrowing animals such as rodents and rats are sensitive to low-oxygen atmospheres and (unlike humans) will avoid them.^[1] For this reason, the use of inert gas hypoxic atmospheres for euthanasia is very species-specific. Nevertheless, after a number of accidents in which humans have been suffocated in nitrogen without any warning, the suggestion was made in 1995 that hypoxic atmospheres be used for the humane killing of humans.

As an execution method

Although execution by nitrogen asphyxiation was discussed briefly in print in 1995 (Creque), it is not used by any nation.

In a televised documentary in 2007,^[2] the UK political commentator (and former Member of Parliament United Kingdom), Michael Portillo examined execution techniques in use around the world and found them unsatisfactory; his conclusion was that nitrogen asphyxiation would be the best method.

Accidental deaths

Accidental nitrogen asphyxiation causes about 8 deaths per year in the United States,^[3] which is asserted to be more than from any other industrial gas. For example in 1981, shortly before the launch of the first Space Shuttle mission, two technicians lost consciousness and one of them died after they entered the Orbiter aft compartment which was pressurized with pure nitrogen as a precaution against fire.^[4]

A laboratory assistant died in Scotland in 1999, apparently from asphyxiation, after liquid nitrogen spilled in a basement storage room.^[5]

Physiology

A typical human breathes between 12 and 20 times per minute at a rate primarily influenced by carbon dioxide concentration, and thus pH, in the blood. With each breath, a volume of about 0.6 liters is exchanged from an active lung volume (tidal volume + functional residual capacity) of about 3 liters. Normal Earth atmosphere is about 78% nitrogen, 21% oxygen, and 1% argon, carbon dioxide, and other gases. After just two or three breaths of nitrogen, the oxygen concentration in the lungs would be low enough for some oxygen already in the bloodstream to exchange back to the lungs and be eliminated by exhalation. Crude simulation of oxygen transport through the lungs and bloodstream suggests that the partial pressure of oxygen in arterial blood would be about 50% of saturation 1 minute after switching gases and would reach zero within 3 minutes.

Unconsciousness in cases of accidental asphyxia can occur within 1 minute. Loss of consciousness results from critical hypoxia, when arterial oxygen saturation is less than 60% (Fisher n.d.). "At oxygen concentrations [in air] of 4 to 6%, there is loss of consciousness in 40 seconds and death within a few minutes" (DiMaio & DiMaio 2001:231). As this procedure provides an atmosphere completely devoid of oxygen, the sequence of effects should be expected to occur even more quickly. At an altitude over 43,000 ft (13,000 m), where the ambient oxygen concentration is equivalent to 3.6% at sea level, an average individual can perform flying duties efficiently for only 9 to 12 seconds without oxygen supplementation (Fisher n.d.). The US Air Force trains air crews to recognize their individual subjective signs of approaching hypoxia. Some individuals experience headache, dizziness, fatigue, nausea, or euphoria, but some become unconscious without warning (Fisher n.d.). Equivalent training is unlikely for a condemned individual, making unconsciousness without warning probable, although as much as a 30 second warning is possible.

Loss of consciousness may be accompanied by convulsions (Fisher n.d.) and is followed by cyanosis and cardiac arrest. About 7 minutes of oxygen deprivation causes death of the cerebral cortex and presumably of the medulla oblongata, which controls breathing and heart action.

See also

• Air hunger
• Asphyxiant gas
• Capital punishment
• Capital punishment debate
• Positional asphyxia
• Suicide bag

References

• Creque, S.A. "Killing with kindness – capital punishment by nitrogen asphyxiation" National Review. 1995-10-11.

• DiMaio V & DiMaio D. "Forensic Pathology, Second Edition. Chapter 8, Asphyxia", ISBN 0-8493-0072-X, 2001. Retrieved on 2007-01-27.

• Fisher PW. "High altitude respiratory physiology, chapter 2 in USAF Flight Surgeon’s Guide", n.d. Retrieved on 2007-02-07.

• Seitz KN. "The Transition of Methods of Execution in North Carolina: A Descriptive Social History of Two Time Periods, 1935 and 1983", PhD dissertation (Sociology) Virginia Polytechnical Institute and State University, 2001. Retrieved on 2007-01-23.

• "Methods of Execution". http://www.deathpenaltyinfo.org/article.php?scid=8&did=245. Retrieved 2007-01-25. 

• "Some Examples of Post-Furman Botched Executions". http://www.deathpenaltyinfo.org/article.php?scid=8&did=478. Retrieved 2007-01-25. 

• "Hazards of Nitrogen Asphyxiation". U.S. Chemical Safety and Hazard Investigation Board. 2003-06-11. Archived from the original on 2007-02-03. http://web.archive.org/web/20070203150950/http://www.csb.gov/safety_publications/docs/SB-Nitrogen-6-11-03.pdf. Retrieved 2007-02-15. 

• "Shuttle Tragedy". Time. 1981-03-31. http://www.time.com/time/magazine/article/0,9171,922499,00.html. Retrieved 2007-01-27. 

• "UK: Scotland Inquiry after man dies in chemical leak". BBC. 1999-10-25. http://news.bbc.co.uk/2/hi/uk_news/scotland/484813.stm. Retrieved 2007-01-27. 

References

External links

• NIOSH respirator fact sheet
• U.S. Chemical Safety and Hazard Investigation Board
• Death Penalty Information Center
• Restraint asphyxia