Nitrogen Suffocation

What to Know

• No execution has been carried out anywhere in the world using nitrogen gas
• There is no scientific evidence on using nitrogen to execute people but it is generally not used to euthanize animals because it causes panic and distress
• Risks include feelings of suffocation and choking to death on one’s own vomit, as well as brain damage, a stroke, or a persistent vegetative state instead of death
• Alabama has the worst record of any state in the country for botched executions
• A mishap with odorless, colorless nitrogen could kill prison staff within minutes

Without Scientific Evidence, States Adopt Never-Before-Used Method

In 2015, Oklahoma became the first state to adopt a measure allowing prison staff to use nitrogen gas to execute people after the botched lethal injection execution of Clayton Lockett in 2014 led to a halt in executions.

No execution has been carried out anywhere in the world using asphyxiation with an inert gas like nitrogen.

Most of what is known about nitrogen hypoxia comes from reports about nitrogen leaks that killed workers in industrial accidents, but those exact conditions cannot be reproduced in a prison execution chamber.

Despite the absence of scientific evidence on executing people using nitrogen suffocation, Mississippi passed a similar law in 2017, and on March 22, 2018, Alabama Gov. Kay Ivey signed legislation making Alabama the third state in the country to allow executions by nitrogen gas.

Risk of Botched Nitrogen Execution

Exposure to less than 100% pure nitrogen gas can cause severe and permanent injuries short of death, according to experts.

Alabama’s protocol calls for delivering nitrogen gas to the condemned person through a mask, which experts say creates a substantial risk that oxygen will infiltrate the mask, which could leave the person in a persistent vegetative state, cause him to have a stroke, or to experience the painful sensation of suffocation.

Vomiting is also a known side effect of oxygen deprivation. Using a mask that covers the nose and mouth creates a risk that the person will asphyxiate on his own vomit, especially where, as here, prison staff will not intervene to check or clear the person’s airway if he vomits after nitrogen has begun to flow.

United Nations experts have expressed alarm over the use of nitrogen gas, which they described as “an untested method of execution which may subject [the condemned person] to cruel, inhuman or degrading treatment or even torture.”

Warning that experimental executions by nitrogen gas asphyxiation will likely violate international bans on torture and other cruel, inhuman, or degrading punishment, the experts said in a statement, “We are concerned that nitrogen hypoxia would result in a painful and humiliating death.”

The U.N. Human Rights Office also expressed serious concerns that execution by nitrogen gas could violate U.S. treaty obligations prohibiting torture, noting that Alabama’s protocol does not provide for a sedative prior to administration of the lethal gas.

Prison Employees May Face Risk of Asphyxiation or Injury

Nitrogen has killed people in industrial and medical accidents. A recent report into a nitrogen leak that killed six workers at a Georgia poultry plant underscored the extreme risks that nitrogen poses to workers’ lives, even in industries and facilities where the hazardous chemical has long been widely and regularly used.

Because nitrogen gas is odorless and colorless, correctional officers, prison staff, and observers at any execution face the risk of asphyxiation in the event of a leak. The Chemical Safety Board warns that “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.”

If nitrogen leaks—because the execution mask is not properly sealed or if a valve detaches—prison staff in the execution chamber may be at risk of injury or death. The Alabama Department of Corrections acknowledged in court that nitrogen gas presents “the dangers of inert-gas asphyxiation to employees.”

Nitrogen Inappropriate for Euthanizing Animals

The American Veterinary Medical Association has declared that nitrogen gas is inappropriate for euthanizing most animals. Its guidelines provide, “Current evidence indicates this method is unacceptable because animals may experience distressing side effects before loss of consciousness.”

“Veterinarians have generally stopped using nitrogen to euthanize animals, who showed severe signs of distress,” The New York Times reports.

Despite Four Consecutive Botched Executions, Alabama to Experiment with Nitrogen Gas

On August 25, 2023, less than 10 months after the State of Alabama failed in its torturous attempt to execute Kenny Smith by lethal injection, the attorney general asked the Alabama Supreme Court to allow a second attempt to put Mr. Smith to death, this time using the unproven, untested method of nitrogen gas. The motion did not provide any details about how a nitrogen gas execution would be carried out.

On November 1, 2023, the Alabama Supreme Court nonetheless granted the attorney general’s motion in a divided order signed by six justices. Chief Justice Tom Parker and Justice Greg Cook dissented, while Justice Kelli Wise recused. A week after the order, Alabama Gov. Kay Ivey set the execution for January 25, 2024.

With its long history of “failed and flawed executions and execution attempts,” EJI senior attorney Angie Setzer told the Associated Press, “Alabama is in no position to experiment with a completely unproven and unused method for executing someone.”

“Nobody really knows what’s going to happen,” Dr. Jeffrey Keller, president of the American College of Correctional Physicians, told The New York Times. “So will he choke? Will he vomit? Will the mask fit or will the nitrogen leak out? Will that nitrogen harm anybody else who is standing nearby? Nobody knows any of this. It’s an experiment.”

“No state in the country has executed a person using nitrogen hypoxia,” Ms. Setzer said. Allowing Alabama to experiment with a never before used method, she added, “is a terrible idea.”