On Thursday, the state of Alabama in the US executed a man using Nitrogen Gas.
This is the first time Nitrogen has been used for a human execution.
The use of nitrogen gas in executions has been approved by three states, including Alabama in 2018, along with Oklahoma and Mississippi.
Kenneth Eugene Smith was originally scheduled to be put to death with deadly drugs in November 2022 but prison officials had difficulty inserting the second intravenous line and had the exercise called off.
Smith, convicted in the 1988 murder of Elizabeth Sennett was executed at Holman Prison in Alabama.
While nitrogen gas has never previously been used to execute humans in the United States, it is sometimes used to kill animals.
According to authorities, the method was picked because it has become difficult to find lethal injection drugs.
The UK and the European Union banned exports of the chemicals in 2011, and five years later American drugs giant Pfizer, the last open-market source of lethal injection drugs, announced it would no longer sell them to be used in executions.
How does it work?
It is done through a process called Nitrogen Hypoxia. It depletes the body of oxygen, causing major organs to shut down.
A respirator mask is placed over the inmate's face and then pure nitrogen is pumped into the person's lungs instead of oxygen.
While nitrogen itself is not poisonous, in pure concentrated form, breathing in the gas chokes off the oxygen supply to the brain.
Execution methods vary, but some states still allow execution by hanging, firing squad or the electric chair.
In recent decades, most states have settled on lethal injection as the main execution method.
Texas was the first state to execute a convicted criminal with lethal injection, in 1982.
Amnesty International recorded 883 executions worldwide in 2022.
