Alabama uses Nitrogen Gas to Execute a Prisoner

ATMORE, Ala. (AP) — Alabama executed a convicted murderer with nitrogen gas Thursday, putting him to death with a first-of-its-kind method that once again placed the U.S. at the forefront of the debate over capital punishment. The state said the method would be humane, but critics called it cruel and experimental.
Officials said Kenneth Eugene Smith, 58, was pronounced dead at 8:25 p.m. at an Alabama prison after breathing pure nitrogen gas through a face mask to cause oxygen deprivation. It marked the first time that a new execution method has been used in the United States since lethal injection, now the most commonly used method, was introduced in 1982.

https://www.yahoo.com/news/alabama-set-execute-inmate-nitrogen-053007615.html

Probably a kinder fate than his victim received.

Yep....
It basically makes a person go to sleep and not wake up. Similar to lethal injection but without the needles or burning sensation by the medication.

Lots of people who work at chemical plants have died because they didn't bother to check the O² sensors and walked right into the nitrogen chamber....even stories of another guy going in to drag the first one out and suffering the same fate.

You can't tell anything is wrong....you don't choke or anything else like that....you simply get sleepy and fall asleep.