Many sources online seem to be claiming that, when in lack of Zyklon B, Nazis used their truck exhaust pipes directly as a source of gas. Is that true?

  • According to Wikipedia, During Operation Reinhard (the genocide of Jews in the occupied Poland), exhaust gas from Russian tank engines was used. However, this statement is sourced to the book "Pope Pius XII and the Holocaust" by John Roth and Carol Rittner which seems to be only tangential related to this and can not be read online.
    – Philipp
    Jul 24, 2014 at 16:54
  • 1
    I removed the speculative part of the question as it's off-topic here. You can ask about the affects of different kinds of smoke and gasses on the human body on the Biology.SE or perhaps the Chemistry.SE sites.
    – SIMEL
    Jul 24, 2014 at 22:07

1 Answer 1


The Nazis did use carbon monoxide (CO) as a lethal gas to kill prisoners, but it wasn't used as an alternative to Zyklon B, but the other way around, Zyklon B was chosen as an alternative to CO. They used CO both in mobile gas chambers (Gas Vans) and in stationary gas chambers (located in death and concentration camps).

They used CO from the exhausts of a truck engine to kill prisoners, mostly Jews. The method has a Wikipedia article, sourced to many sources, indicating that the first to use this method of execution were the NKVD, the soviet secret police.

The gas van was invented in the Soviet Union in 1936, by Isay Berg, the head of the administrative and economic department of the NKVD of Moscow Oblast which suffocated batches of prisoners with engine fumes in a camouflaged bread van while on the drive out to the mass graves at Butovo, where the prisoners were subsequently buried.

The United States Holocaust Memorial Museum, on their web page about the Nazis gassing operation state:

After the June 1941 German invasion of the Soviet Union and Einsatzgruppe (mobile killing unit) mass shootings of civilians, the Nazis experimented with gas vans for mass killing. Gas vans were hermetically sealed trucks with engine exhaust diverted to the interior compartment. Use of gas vans began after Einsatzgruppe members complained of battle fatigue and mental anguish caused by shooting large numbers of women and children. Gassing also proved to be less costly. Einsatzgruppen (mobile killing units) gassed hundreds of thousands of people, mostly Jews, Roma (Gypsies), and mentally ill people. In 1941, the SS concluded that the deportation of Jews to killing centers (to be gassed) was the most efficient way of achieving the "Final Solution". That same year, the Nazis opened the Chelmno camp in Poland. Jews from the Lodz area of Poland and Roma were killed there in mobile gas vans.

The Gas Vans were not a substitution for the Zyklon B gas chambers, but the other way around, as the page in USHMM continues to point out that the first stationary gas chambers also used carbon monoxide exhaust from engines:

In 1942, systematic mass killing in stationary gas chambers (with carbon monoxide gas generated by diesel engines) began at Belzec, Sobibor, and Treblinka, all in Poland.

And that the Nazis switched to ZyKlon B because it was more efficient:

The Nazis constantly searched for more efficient means of extermination. At the Auschwitz camp in Poland, they conducted experiments with Zyklon B (previously used for fumigation) by gassing some 600 Soviet prisoners of war and 250 ill prisoners in September 1941. Zyklon B pellets, converted to lethal gas when exposed to air. They proved the quickest gassing method and were chosen as the means of mass murder at Auschwitz. At the height of the deportations, up to 6,000 Jews were gassed each day at Auschwitz.

  • interesting, I wonder why they didn't just fill completely (hermetic) chambers with water, death by drowning may be less suffering, Do you also know if survivors from gas chambers if there were any (who were exposed to the gas) had suffered from mental disabilities later? the consequences of inhaling CO or other toxic gas at those concentrations may be irreversible (anyway I'm also sad they used it on humans in a totally absurd way, just interested in the toxicity like you answered well)
    – caub
    Jul 25, 2014 at 12:19
  • If you want to know more about CO poisoning, just go to its wiki page.
    – SIMEL
    Jul 26, 2014 at 7:55
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    @n11 the amount of suffering never entered into the equation. And it's a lot easier to build a room to able to contain the gas than it is to build one (and the support infrastructure) to contain a large volume of water.
    – jwenting
    Jul 6, 2015 at 11:11
  • They also did mass executions using firearms. See en.m.wikipedia.org/wiki/Einsatzgruppen.
    – jjack
    Jul 17, 2015 at 22:01
  • I have read that near the end of the war some of the 'holocaust trains' were configured so that the exhaust fed directly into the stock cars.
    – PCARR
    Oct 19, 2015 at 15:49

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