The cryogenic industrial scale separation of nitrogen (and oxygen) from air can be traced back to 1895 when
In May 1895, Carl von Linde performed an experiment in his laboratory in Munich that led to his invention of the first continuous process for the liquefaction of air based on the Joule-Thomson refrigeration effect and the principle of countercurrent heat exchange. This marked the breakthrough for cryogenic air separation.
Cryogenic separation is normally used to produce nitrogen (78.1%), oxygen (20.9%) and argon (0.9%). Other methods are used for separating and concentrating the other trace gases in the atmosphere. Nitrogen is stable, non-explosive and inert. The growth of the chemical and oil refining industries saw a huge increase in the use of nitrogen for its physical and chemical properties. Since it is transported and stored in liquid form (cryogenic tanks) it could provide a source of “cold”, could come at very high pressures and was chemically inert. Moreover it was a raw material that was needed for the manufacture of fertilisers and pharmaceuticals. Its industrial use and medical use is widespread. Nitrogen is used – among many other things – as an assist gas for laser cutting, in creating welding atmospheres, as a pressurising gas in liquid pipelines, as a shielding or blanketing material for explosive or oxygen-sensitive materials, as a purging agent when cleaning tanks or pipes and as a freezing agent. Today there are few hospitals or factories (in any industry) which do not have a nitrogen storage facility of some kind.
In power plants nitrogen is often used for pressurising, purging, cooling or protection. I first came across a death caused by nitrogen in the 1970s when a maintenance worker entered a pulverised coal storage silo which had been blanketed with nitrogen for explosion protection during a shut-down. It was not a pressurised silo and therefore not seen as being a high risk area. By accident, he had entered the silo without a companion being present and without his breathing equipment. He was only found hours later inside the silo and it became clear that his asphyxiation had happened so fast that he had had no time to struggle, let alone call for any assistance. Of course the death was not so much caused by nitrogen as by the lack of oxygen and the resulting hypoxia. Nitrogen asphyxiation is not unknown as an industrial cause of death. Through the 1980s and 1990s, I came across another 4 accidental deaths at power plants where workers had inadvertently entered a nitrogen atmosphere. Just in the US, there were 80 industrial deaths and 50 injuries due to nitrogen asphyxiation between 1992 and 2002.
Effects of oxygen deficiency US CSB
Nitrogen cylinders are readily available and nitrogen asphyxiation has already become – unofficially of course – one of the methods being used for end-of-life assisted deaths and suicides. It is said that the subject feels light-headed and euphoric first due to oxygen deficiency and then slips into unconsciousness and a supposed painless death. In an atmosphere with 4-6% oxygen, unconsciousness and a coma result in less than 40 seconds. An oxygen mask connected to a nitrogen – rather than an oxygen – cylinder is all that is apparently required. We cannot know for sure but it is thought that the subject:
is not stunned by the burning urge to breathe or the choking sensation of not having any air. As far as he realizes, he is breathing normally. Carbon dioxide is not building up in his bloodstream, so he never realizes that he is in danger. The subject is never in any pain he simply just passes out when his blood oxygen level falls to(o) low.
And now the State of Oklahoma is proposing that nitrogen asphyxiation be used as method of “humane” execution. (I think “humane” in this context is just a euphemism for “quick, unconscious and painless”).
Washington Post: ….. But in Oklahoma, a bill is advancing that would introduce an entirely new and untested method of execution: death by nitrogen inhalation.
“It’s probably the best thing we’ve come up with since the start of executing people by government,” the bill’s sponsor, Rep. Mike Christian (R) told the Oklahoman.
Nitrogen gas itself is odorless and nontoxic, and makes up 78 percent of the atmosphere. It only becomes lethal when someone breathes it in at high concentrations, and only then because that person is therefore not getting enough oxygen.
The proposed law is vague on the exact procedure, but Christian has said that it would be cheap and simple. Some kind of bag or breathing mask would be placed around the inmate’s head. Nitrogen gas would be pumped in, displacing any oxygen. The inmate would start to feel lightheaded, possibly euphoric, which are symptoms of oxygen deprivation. Painless death would soon follow.
Or that’s what’s supposed to happen, though nobody really knows for certain. (Generally speaking, medical professionals refuse to conduct research into killing methods.) ……
…. At Rep. Christian’s behest, professors at East Central University recently produced a report on death by nitrogen.
Report recommendations:
Nitrogen Induced Hypoxia as a Form of Capital Punishment,
Michael Copeland JD., Thom Parr MS. and Christine Papas JD., PhD.
The study found that:
1. An execution protocol that induced hypoxia via nitrogen inhalation would be a humane method to carry out a death sentence.
2. Death sentence protocols carried out using nitrogen inhalation would not require the assistance of licensed medical professionals.
3. Death sentences carried out by nitrogen inhalation would be simple to administer.
4. Nitrogen is readily available for purchase and sourcing would not pose a difficulty.
5. Death sentences carried out by nitrogen inhalation would not depend upon the cooperation of the offender being executed.
6. Use of nitrogen as a method of execution can assure a quick and painless death of the offender.
Accordingly, it is the recommendation of this study that hypoxia induced by the inhalation of nitrogen be offered as an alternative method of administering capital punishment in the State of Oklahoma.
In this modern, civilised, 21st century, firing squads, beheadings, stoning, being pushed off a roof-top, being poisoned (gas, lethal injection), hanging, electrocution and asphyxiation are all in use or proposed as methods of execution. Not so very different from the barbarous times of the Middle Ages.
