Alabama plans to carry out first nitrogen gas execution. How will it work and what are the risks?

MONTGOMERY, Ala. (news agencies) — Alabama is preparing to use a new method of execution: nitrogen gas.

Kenneth Eugene Smith, who survived the state’s previous attempt to put him to death by lethal injection in 2022, is scheduled to be put to death Thursday by nitrogen hypoxia. If carried out, it would the first new method of execution since lethal injection was introduced in 1982.

The state maintains that nitrogen gas will cause unconsciousness quickly but critics have likened the never-used method of execution to human experimentation.

Nitrogen hypoxia execution would cause death by forcing the inmate to breathe pure nitrogen, depriving him or her of the oxygen needed to maintain bodily functions.

No state has used nitrogen hypoxia to carry out a death sentence. In 2018, Alabama became the third state — along with Oklahoma and Mississippi — to authorize the use of nitrogen gas to execute prisoners.

Some states are looking for new ways to execute inmates because the drugs used in lethal injections, the most common execution method in the United States, are increasingly difficult to find.

Nitrogen, a colorless, odorless gas, makes up 78% of the air inhaled by humans and is harmless when breathed with proper levels of oxygen.

The theory behind nitrogen hypoxia is that changing the composition of the air to 100% nitrogen will cause Smith to lose consciousness and then die from lack of oxygen.

Much of what is recorded in medical journals about death from nitrogen exposure comes from industrial accidents — where nitrogen leaks or mix-ups have killed workers — and suicide attempts.

After Smith is strapped to the gurney in the execution chamber, the state said in a court filing that it will place a “NIOSH-approved Type-C full facepiece supplied air respirator” — a type of mask typically used in industrial settings to deliver life-preserving oxygen — over Smith’s face.

The warden will then read the death warrant and ask Smith if he has any last words before activating “the nitrogen hypoxia system” from another room. The nitrogen gas will be administered for at least 15 minutes or “five minutes following a flatline indication on the EKG, whichever is longer,” according to the state protocol.

The state heavily redacted sections of the protocol related to the storage and testing of the gas system.

The Alabama attorney general’s office told a federal judge that the nitrogen gas will “cause unconsciousness within seconds, and cause death within minutes.”

Smith’s attorneys say the state is seeking to make him the “test subject” for a novel execution method.

They have argued that the mask the state plans to use is not air tight and oxygen seeping in could subject him to a prolonged execution, possibly leaving him in a vegetative state instead of killing him. A doctor testified on behalf of Smith that the low-oxygen environment could cause nausea, leaving Smith to choke to death on his own vomit.

Experts appointed by the United Nations Human Rights Council earlier this month cautioned that, in their view, the execution method would violate the prohibition on torture and other cruel, inhuman or degrading punishment.

The American Veterinary Medical Association wrote in 2020 euthanasia guidelines that nitrogen hypoxia can be an acceptable method of euthanasia under certain conditions for pigs but not for other mammals because it creates an “anoxic environment that is distressing for some species.”

Not exactly. Some states previously used hydrogen cyanide gas, a lethal gas, for executions. The last prisoner to be executed in a U.S. gas chamber was Walter LaGrand, the second of two German brothers sentenced to death for killing a bank manager in 1982 in southern Arizona. It took LaGrand 18 minutes to die in 1999.

Smith was one of two men convicted of the 1988 murder-for-hire of a preacher’s wife. Prosecutors said Smith and the other man were each paid $1,000 to kill Elizabeth Sennett on behalf of her husband, who was deeply in debt and wanted to collect insurance money.

Alabama attempted to execute Smith in 2022 by lethal injection. He was strapped to the gurney in the execution chamber being prepared for lethal injection, but the state called off the lethal injection when execution team members had difficulty connecting the second of two required intravenous lines to Smith’s veins. Smith was strapped to the gurney for nearly four hours, according to his lawyers, as he waited to see if the execution would go forward.