In 1998, the Los Angeles Times reported the following story about a student who committed suicide by orally ingesting potassium cyanide:
https://www.latimes.com/archives/la-xpm ... story.html or https://archive.is/aac7C9 Hurt After Student’s Apparent Suicide by Cyanide
Toxic fumes produced when a college student from Orange County died of an apparent suicide Monday forced the evacuation of an Iowa dormitory and the hospitalization of nine people, authorities said.
Carl T. Grimm, 20, a sophomore from Placentia, ingested potassium cyanide about 7:30 a.m. in his dormitory room at Grinnell College, a private liberal arts school about 50 miles east of Des Moines, Iowa, Grinnell Fire Chief Jerry Barns said.
Four paramedics who responded to the call at Younkers Hall came in contact with fumes from the poison, as did two college staff members and three other students.
Grimm was taken to Grinnell Regional Medical Center, where he was pronounced dead.
The others who became ill on the Iowa campus were treated and released from the hospital.
“When potassium cyanide is mixed with water or mixed with acid, it creates hydrogen cyanide gas, which is quite toxic. Eighty percent of the body is made of water,” said Mickey Munley, the college’s director of public relations.
Potassium cyanide is a respiratory poison that prevents oxygen from reaching the cells. When ingested, it causes death almost immediately.
Firefighters sent to the dormitory evacuated the three-story structure until the Des Moines Hazardous Materials Unit arrived to ventilate the building.
A gas mask alone is not necessarily even sufficient, as the poison can absorb into your skin especially if you are sweating. I don't think these "Sonderkommando" would have survived pulling out even one batch of gassed prisoners from the poorly ventilated "homicidal gas chamber" without gear covering all of their exposed skin.
The Chemistry of Auschwitz
Cyanide Chemistry at Auschwitz
Pressac’s Solution – Gas Chamber Ventilation
Auschwitz: Eyewitness Reports and Perpetrator Confessions of the Holocaust—30 Gas-Chamber Witnesses Scrutinized
Infographic debunking the Auschwitz gassings