Inert gas asphyxiation

Inert gas asphyxiation is a form of asphyxiation which results from breathing a physiologically inert gas in the absence of oxygen, or a low amount of oxygen,[1] rather than atmospheric air (which is composed largely of nitrogen and oxygen). Examples of physiologically inert gases, which have caused accidental or deliberate death by this mechanism, are argon, helium, nitrogen and methane.[citation needed] The term "physiologically inert" is used to indicate a gas which has no toxic or anesthetic properties and does not act upon the heart or hemoglobin. Instead, the gas acts as a simple diluent to reduce the oxygen concentration in inspired gas and blood to dangerously low levels, thereby eventually depriving cells in the body of oxygen.[2]

According to the U.S. Chemical Safety and Hazard Investigation Board, in humans, "breathing an oxygen deficient atmosphere can have serious and immediate effects, including unconsciousness after only one or two breaths. The exposed person has no warning and cannot sense that the oxygen level is too low." In the US, at least 80 people died from accidental nitrogen asphyxiation between 1992 and 2002.[3] Hazards with inert gases and the risks of asphyxiation are well-established.[4]

An occasional cause of accidental death in humans, inert gas asphyxia has been used as a suicide method. Inert gas asphyxia has been advocated by proponents of euthanasia, using a gas-retaining plastic hood device colloquially referred to as a suicide bag.

Nitrogen asphyxiation has been approved in some places as a method of capital punishment. In the world's first instance of its use, on January 25, 2024, Alabama executed convicted murderer Kenneth Eugene Smith via this method. It was used once again in the execution of Alan Eugene Miller, on September 26, 2024[5]

Alternatively, the use of the term hypoxia has been used but this term is flawed given hypoxia does not necessarily imply death. On the other hand, asphyxiation is technically incorrect given respiration continues and the carbon dioxide metabolically produced from the oxygen inhaled prior to inert gas asphyxiation can be exhaled without restriction, which can prevent acidosis and the strong urge to breathe caused by hypercapnia.[6]

  1. ^ European Industrial Gases Association (2009), Hazards of Inert Gases and Oxygen Depletion, Archived 2017-05-17 at the Wayback Machine, IGC Doc 44/09/E
  2. ^ Cite error: The named reference Wilkenfield was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference CSB.gov Safety Bulletin was invoked but never defined (see the help page).
  4. ^ "Hazards of Inert Gases and Oxygen Depletion". Singapore: Asia Industrial Gases Association.
  5. ^ "Alabama puts to death Kenneth Smith in first known execution using nitrogen gas". CNN. 25 January 2024. Archived from the original on 26 January 2024. Retrieved 26 January 2024.
  6. ^ Copland, Michael; Parr, Thom; Paras, Christine. Nitrogen Induced Hypoxia as a Form of Capital Punishment (PDF) (Report). Archived (PDF) from the original on 2023-10-22. Retrieved 2023-11-02.