MC Explains: What is nitrogen hypoxia and how does it work?

Nitrogen hypoxia is the first new method of execution to be introduced since 1982 when lethal injections began being used.

An Alabama death row inmate has been put to death by nitrogen gas, in the first known execution of its kind in the US. His case marks the first known execution by nitrogen hypoxia, which his lawyers had argued amounted to a form of “cruel and unusual punishment”. Death by nitrogen gas is an untested procedure, and its opponents say it can cause unnecessary suffering.

Kenneth Smith, 58, was a contract killer who had been on the death row since 1996. He was convicted for the murder of Elizabeth Sennett in 1989, according to BBC.

What is nitrogen hypoxia?

Nitrogen hypoxia is a style of execution wherein an inmate is made to inhale nitrogen instead of oxygen, leading to gradual asphyxiation. To achieve this, a respirator mask is placed over the head of the inmate on death row.

While the air we breathe is made up of 80 percent nitrogen, it exists in combination with oxygen, rendering the colourless, odourless gas harmless. However, if a person is deprived of oxygen and made to breathe in just nitrogen, the gas proves lethal.

MC Explains

A report by USA Today quoted Joel Zivot, an associate professor in anaesthesiology, as saying: “What is known is that nitrogen gas, under certain circumstances, can cause death.”

When a high concentration of nitrogen is inhaled, it replaces the oxygen in the body and disables the respiratory system, causing death.

Why nitrogen hypoxia?

Nitrogen hypoxia is the first new method of execution to be introduced since 1982 when lethal injections began being used.

The drug needed to administer lethal injections to inmates on death row became harder to access over time, pushing authorities to scout for alternatives. Further, there were reports of a surge in complications associated with the procedure as well. Even Smith, for that matter, was slated to be executed using lethal injection back in 2022. However, the officials were reportedly unable to set up an intravenous line in time.

As of now, only three states in the United States have approved the use of nitrogen gas to execute death row inmates, namely, Alabama, Oklahoma, and Mississippi.

Is nitrogen hypoxia ethical?

Professor Zivot has pointed out the risks associated with this method of execution including the risks surrounding the chances of a gas leak if the mask is not secured well on the inmate. He even submitted a formal complaint to the UN Human Rights Council stating the method is “cruel”.

He said: “The law requires that this execution not be cruel. From what has been described to me, what I know about nitrogen gas and how it may work, this to me feels well within the definition of cruelty.”

The United Nations has since raised concerns about the use of nitrogen hypoxia to execute inmates. “We are concerned that nitrogen hypoxia would result in a painful and humiliating death,” a group of UN experts said.

According to an Al Jazeera report, Smith only struggled for two minutes after the nitrogen gas started being released into the mask. He was reportedly conscious for quite some time before taking his last breath 22 minutes into the process.