The Chemistry Behind Mass Extermination

Most of us, when asked about the substance used for murdering people on an industrial scale, will mention Zyklon B as the chemical agent behind the death of masses. In fact, there is one more simple chemical responsible for mass extermination – carbon monoxide from exhaust fumes.

Zyklon B was actually a cyanide-based pesticide. Its major component, hydrogen cyanide, interferes with cellular respiration, blocking the cell from producing energy. However, the original use of Zyklon B was disinfecting clothes and other fabrics. Later, the Nazis began using the agent as the killing tool in extermination camps. Approximately, 1.1 million people lost their lives in gas chambers at Auschwitz-Birkenau, Majdanek, and other camps. Most of the victims were Jewish. However, the first gassing using Zyklon B was carried out in the basement of Block 11 in Auschwitz I in late August 1941. The “test subjects” were Soviet prisoners of war. Eventually, the basement was considered an inappropriate place for gassing as it was difficult to air out and the crematorium was located at quite a distance. Thus, the process was moved to the crematorium (Crematorium I in the main camp), where up to 700 people could be killed at once. Crematorium I operated until June 1942. Then, the killing process was moved to Auschwitz II-Birkenau, which had been under construction since October 1941.

Contrary to common belief, gas chambers as such did not exist in AIIB from the very beginning. The first provisional “gas chambers” were: the so-called “red house” (or Bunker 1, as the SS staff would name it), a brick cottage turned into a gas chamber by bricking up the windows, operational by March 1942, and the so-called “white house” (or Bunker 2), another brick cottage converted into a makeshift gas chamber. Bunkers 1 and 2 were in operation until early 1943, when the Nazis decided to expand the killing potential of the camp. Crematorium II, originally designed as a mortuary, was converted into a huge gas chamber by installing gas-tight doors and special vents through which the pellets of Zyklon B were dropped into the chamber. A popular myth states that Zyklon B was a gas poured from fake showers. In fact, the gas was created when pellets started to dissolve. There was also a special ventilation system for removing the gas after the killing process was finished. Crematorium III was built using the same patterns as Crematorium II, and Crematoria IV and V were designed to be gas chambers from their very beginning. All four Birkenau crematoria were operational by June 1943.

The application of Zyklon B for mass killing is a fact supported by much evidence. Chemistry comes in handy, of course: until today, “Prussian blue” can still be seen on the walls of the gas chamber in Majdanek. It is a residue consisting of a dark blue pigment produced by oxidation of ferrous ferrocyanide salts – the result of the chemical reactions taking place while using Zyklon B. Of course, the gas chamber in Majdanek was used to a much lesser extent for murdering people and the scale of crime is incomparable with respect to Auschwitz-Birkenau. However, let’s remember that Crematoria II-V were blown up when the Red Army was approaching.

What about carbon monoxide?

Let us start with gas vans, mobile gas chambers, whose origins date back to Nazi Euthanasia Program (“Aktion T4”), targeted at eliminating disabled and mentally ill people, commenced in September 1939. In search for a rapid and efficient killing mechanism, the Nazis started to implement the idea of murdering with exhaust fumes. Experimental gassing was carried out in October 1939 in Fort VII in Posen (today: Poznań); the victims were Polish and Jewish inmates of asylums for the mentally ill. According to testimonies, since December 1939, mobile gas chambers were used to murder the inmates of asylums in Eastern Prussia, Pomerania, and in occupied Poland. Gas vans were disguised back then, labeled Kaiser’s Kaffee Geschäft (“Kaiser's Coffee Shop”) in order to hide the process from the society. The whole idea behind gas vans was that the victims were not brought to gas chambers – instead, gas vans themselves were gas chambers.

How did gas vans end up at the Chełmno extermination camp? In August 1941, Reichsführer-SS Heinrich Himmler witnessed the mass shooting of Jews in Minsk. After the shooting, he vomited and ordered to find a more “convenient” way of killing to be found. Various experiments led to the development of gas vans. Apart from Chełmno on the Ner, where approximately 180 thousand people were murdered during both periods of operation of the camp, gas vans were also used by the Einsatzgruppen in the East. The vehicles directed deadly exhaust gases via metal pipes into cargo compartments, where victims were tightly stuffed to capacity. They died from carbon monoxide poisoning on their way to mass graves in the form of pits or ravines.

But exhaust fumes were also used at the Treblinka extermination camp. According to the Nizkor Project, 500 BHP engines from captured  Soviet T-34 tanks were the source of exhaust gases in the gas chambers at Treblinka. Due to lack of solid information and different testimonies, there are still disputes over the actual type of engine used, and even the fact if exhaust fumes were used at Treblinka at all.

Will we ever know?