Alabama's Nitrogen Execution Method Raises Concerns

Experts and activists warn that the untested nitrogen execution method Alabama is planning to employ could carry more risks to both a prisoner and witnesses than a lethal injection.

In November 2022, the execution of Kenneth Smith in an Alabama prison was postponed after the prison officials failed to insert an intravenous line into his arms, hands, and veins near his heart.

It wasn't the first time the prison lethal injection — the usual execution method in the United States — couldn't be administered. As a result, Alabama is now looking for new ways to carry out the death penalty.


Smith is poised to become the first person in the U.S. to be executed using nitrogen hypoxia, a method where pure nitrogen gas is inhaled to cause asphyxiation.

While nitrogen is used in assisted suicides in Europe and Australia, Alabama's decision to carry out nitrogen hypoxia using a mask raised concerns over causing unnecessary suffering for Smith and endangering the lives of witnesses.

Experts say it's 'painful' and 'humiliating'

Nitrogen, a colorless and odorless gas, makes up 78% of the air we breathe. However, it is safe to breathe only when mixed with the appropriate amount of oxygen, according to the Chemical Hazard Safety Investigational Board.

During the execution, Smith will be strapped to a gurney, and a mask will be placed on his face. Then, nitrogen will be pumped through a gas mask for at least 15 minutes until all oxygen is depleted from Smith's body and he dies.

Officials say nitrogen hypoxia will cause Smith, convicted in 1989 for committing the murder-for-hire of a preacher's wife, to lose consciousness before he dies from the lack of oxygen.

Human rights activists, however, are not convinced that nitrogen hypoxia is a humane method to carry out an execution.

United Nations experts expressed concern that nitrogen hypoxia would result in a "painful and humiliating death." They warned that experimental executions by gas asphyxiation will likely contribute to torture.


Dr. Joel Zivot, M.D., FRCPC, an associate professor at Emory University School of Medicine, says by using nitrogen hypoxia, the state is taking a risk that the procedure will not go as planned.

I'm not here as an apologist for Kenneth Smith's actions and I understand that a murder took place. But as a prisoner, he still has rights, even within his punishment. I have significant concerns that it could be a torture because the nitrogen gas may leak around the mask, and he could vomit into the mask.


Dr. Philip Nitschke, an inventor of a pod filled with nitrogen to use in assisted suicide, says that both lethal injection and nitrogen hypoxia, if carried out incorrectly, poses the risk of leaving a person technically alive but with serious brain damage. However, it is more likely to happen with nitrogen hypoxia.

“With the planned nitrogen hypoxia method, any dislodgement of the fitted face mask, so that a seal between mask and face is not maintained, could lead to air/oxygen being drawn into the lungs during deep gasping inspiration,” Nitschke tells Healthnews.

Because the cerebral damage would be done while the person is unconscious, it might be difficult to describe the execution as painful, Nitschke explains. Moreover, it is difficult to say what would be worse — failed lethal drugs or failed hypoxia.

The American Veterinary Medical Association says nitrogen hypoxia is an unacceptable euthanasia method for most mammals due to its distressing effects.

If the method is employed anyway, it is recommended that large animals be given a sedative. Meanwhile, Alabama's protocol for nitrogen hypoxia executions does not include sedation.

Zivot says sedation is a medical act, and giving people medications so they can better prepare for execution is outside of the ethical practice of medicine.

He adds, “There's nothing in the practice of medicine that permits prescribing of a medication so a person can be more fit to be executed.”

The children of Elizabeth Sennett, a victim of Smith, are not concerned about the execution method, especially after it was already postponed.

"Well, he didn't ask Mama how to suffer. They just did it. They stabbed her multiple times," her son, Charles Sennett Jr., told WAAY 31 television.


On Wednesday, the Supreme Court and a federal appeals court each declined to intervene to stop Alabama from carrying out nitrogen hypoxia on Smith. In Smith’s appeal, his lawyers argued that the untested execution method would violate his Eighth Amendment right not to have cruel and unusual punishments inflicted on him.

Potential risks for witnesses

Rev. Jeff Hood, Smith's spiritual advisor who will be in the room where the execution will take place, said he was required to sign a waiver warning about the potential health risks of nitrogen.

For Zivot, the request to sign a waiver is an acknowledgement of the fact that the officials are not prepared for carrying out nitrogen hypoxia.

He says, “There's no option in the death sentence or in punishment to punish other people in the vicinity.”

Alison Mollman, the interim legal director of the American Civil Liberties Union in Alabama, called nitrogen a lethal threat to the prison staff and the public. Testifying before the Alabama State Legislature's Joint Prison Oversight Committee in December, she said that the plans for the execution must be stopped.

She pointed to well-documented cases of deadly accidents involving nitrogen. In 2021, a leak allowed nitrogen gas to fill a freezer room at a poultry plant in Gainesville, Georgia. Six workers died, and another 13 people, including four first responders in safety gear, required hospitalization and intensive care.

"The question isn't if nitrogen gas will kill ADOC staff; the question is when," Mollman said.

A study conducted at the request of the state of Oklahoma concluded that induced hypoxia via nitrogen inhalation would be a humane method to carry out a death sentence as it can assure a quick and painless death.

The authors say that because of the simplicity of the method, mistakes are unlikely to occur, and the risks to witnesses are minimal, as any potential leak of nitrogen would not be harmful in a normally ventilated environment.

Meanwhile, Zivot says he has concerns about the ethical knowledge of many physicians willing to cooperate on execution methods.


He tells Healthnews, "It's unambiguous that the medical doctor's job is not to help the state punish people."


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