A New Method of Execution: Nitrogen Hypoxia

Nitrogen hypoxia is a novel method of execution. However, its ethics remains a question.

Reading Time: 4 minutes

Cover Image
By Lillian Zou

Kenneth Smith laid on his execution bed, awaiting his inevitable death. Smith had been sentenced to death since 1996, and, after numerous failed executions, was successfully put to death on January 25, 2024, by a novel and previously unused method: nitrogen hypoxia. However, debates on whether this execution was truly a success still remain. 

The death penalty, initially brought by the British in the 1600s, has long been a contentious subject throughout the U.S., and hanging was the most common method of execution. Since then, intellectuals have criticized execution and sought more humane methods. In 1924, Nevada introduced the use of cyanide gas, which marked one of the first uses of gas as a means of execution. Currently, the main means of execution for the death penalty in America is lethal injection. 

Lethal injection is the practice of injecting three drugs into a person: typically a barbiturate, paralytic, and potassium solution for the purpose of rapid death. Midazolam, an anesthetic, renders an inmate unconscious by slowing down the central nervous system. Vecuronium bromide competes with acetylcholine, a neurotransmitter responsible for regulating cardiac contractions, for receptor sites located on cardiac tissue, hindering contraction and paralyzing the inmate. Potassium chloride interrupts the electrical activity of the heart and stops it. 

 Normally, these drugs take effect within minutes, but a botched execution could cause prolonged suffering. In one case, the drugs caused vomiting and convulsions. In another, the prisoner gasped and snorted for nearly two hours before dying. Additionally, due to medical ethic principles, a medical physician cannot participate in legally authorized executions. Thus, lethal injections are normally administered by inexperienced prison workers. These workers are often unable to identify the IV lines necessary to administer the drugs, leaving puncture wounds and incisions and delaying the execution. This happened to Smith when executioners failed to find a suitable vein, leading to the use of nitrogen hypoxia as a way to kill him.

Nitrogen hypoxia is effectively another term for suffocation. In the case of Kenneth Smith, executioners fit a mask over his nose and mouth and pumped in pure nitrogen. Deprived of oxygen, Smith reached a state of hypoxia: the condition in which the body has insufficient oxygen. This means homeostasis, or internal stability, cannot be maintained, resulting in the decline of organ function. If the bloodstream can’t deliver enough oxygen to organs and tissues, cells cannot create enough energy to function, use the remaining oxygen, and shut down, similar to how a candle burns out when a lid is placed over the flame. 

Nitrogen gas, a necessity in life, is contrastingly fatal in this scenario. Breathing in pure nitrogen, or any inert gas, will lead to asphyxiation: the deprivation of oxygen causing unconsciousness. Most inert gasses are noble gasses, hence they are unreactive due to their full valence shells. Nitrogen, on the other hand, is not a noble gas but is still nonreactive due to its triple bond requiring a great amount of energy to break. Inert gasses do not react with oxygen already present in the body, but rather displace it. Therefore, the human body doesn’t feel suffocation from this asphyxiation. Hypercapnia, the feeling of suffocating, isn’t derived from a lack of oxygen but rather an excess of carbon dioxide. 

Death by nitrogen hypoxia isn’t a new concept—controlled atmosphere killing, considered a more humane way of killing, is used for slaughtering animals. Livestock are often placed in a container of an asphyxiant gas lacking oxygen, which causes the animals to lose consciousness. Nitrogen gas has also been fatal in the industrial setting. In 2017, a Houston mechanic died after accidentally connecting his respirator to a nitrogen hose instead of the compressed air hose. Additionally, Australian doctor Dr. Philip Nitschke developed a pod allowing terminally ill patients to initiate their deaths with the flip of a switch, slowly replacing the oxygen gas in the pod with nitrogen gas. However, Dr. Nitschke, who witnessed over 50 deaths by nitrogen gas, stated that while his pod results in peaceful death, the use of a mask could lead to substantial distress and pain.

According to state officials, Kenneth Smith’s death should’ve been swift, occuring in seconds. However, reports from Alabama journalists who witnessed the execution are different. Over 30 minutes passed from the time the execution began to the moment Smith was pronounced dead. Additionally, Smith was said to have appeared conscious for several minutes after the flow of nitrogen gas began, writhing for at least two minutes, and proceeded to breathe heavily for several minutes before eventually passing. Alabama Corrections Commissioner John Q. Hamm claimed Smith held his breath, causing his own suffering. According to state attorney general Steve Marshall, the execution went completely as predicted, proving nitrogen hypoxia as a humane method of execution. 

The future of nitrogen hypoxia remains unclear. There is little research on the effects of nitrogen gas on the human body, yet officials vow to continue using this method in executions. Nitrogen hypoxia’s use as an execution method will be determined as investigations continue.