Zyklon B Was Used for Delousing Not Killing

This claim turns on the half-true premise that Zyklon B was indeed used as a delousing agent. It was. The German military, the SS and many other European institutions used it routinely from the 1920s onwards to fumigate clothing, bedding, ships’ holds and railway carriages against typhus-carrying lice. The same product was also used at Auschwitz, Majdanek and Stutthof to kill human beings. The two uses were not incompatible because the active substance, hydrogen cyanide, kills both lice and humans by the same biochemical mechanism: inhibition of cellular respiration through binding to the iron centres of cytochrome c oxidase in the electron transport chain. The dosage and exposure time differ; the chemistry does not.

What Zyklon B is

Zyklon B (Cyclone B) was the trade name of a fumigation product manufactured by Degesch (Deutsche Gesellschaft für Schädlingsbekämpfung), a subsidiary jointly owned by IG Farben and Degussa, from the 1920s onwards. The active ingredient was liquid hydrogen cyanide (HCN, also called prussic acid), absorbed onto a porous carrier material (originally diatomaceous earth, later wood-fibre granules and gypsum). The product was supplied in sealed metal cans of various sizes; on opening, the carrier slowly released gaseous HCN over several hours as it warmed to ambient temperature. The product also contained a stabiliser and an irritant warning agent (a tear-gas-like compound) added to alert humans to its presence during routine fumigation work. The Auschwitz-specification Zyklon B had the warning agent omitted from October 1942 onwards, on the explicit request of the SS, who did not want their victims warned. The Degesch correspondence requesting the modification survives in the Nuremberg trial documents.

The killing power of HCN against humans was well understood. The substance was used in American gas chamber executions from 1924 onwards (first in Nevada, then adopted by several other states); the lethal concentration for an unprotected adult is approximately 300 parts per million in air, with death typically occurring within a few minutes of exposure. The SS used Zyklon B to kill at concentrations far in excess of the human lethal dose, achieved by the simple expedient of throwing many cans into a sealed chamber containing several hundred to over a thousand people in a tightly packed space. The chemistry is straightforward and uncontroversial.

The two parallel uses at Auschwitz

The Auschwitz camp had buildings explicitly designated for both uses. The delousing chambers (Entwesungsanlagen, sometimes called Entwesungskammern) were used for fumigating prisoner uniforms, blankets and other infested fabrics. They are well documented in the Zentralbauleitung construction files: the buildings labelled BW 5a and 5b, and the gas-tight chambers in Block 1 of the BIa section. They were equipped with hot-air heating to accelerate the release of the cyanide from the granules and with mechanical ventilation systems to clear the gas after fumigation. They survive in some cases (the BW 5a building still stands) and have been documented by archaeological and architectural survey.

The killing chambers (Vergasungskeller, gas-tight basements, and the surface gas chambers at crematoria IV and V) were entirely separate buildings. The architectural drawings, the construction correspondence, the requisition orders for the gas-tight doors with peep-holes, and the introduction columns through which the SS dropped the Zyklon B cans, all survive in the Zentralbauleitung files. They are physically distinguishable buildings serving different functions in different parts of the camp. The standard Pressac volume, Auschwitz: Technique and Operation of the Gas Chambers (1989), reproduces the relevant drawings and lists the specific differences. The denial that the killing chambers were anything other than delousing facilities requires the listener to disbelieve the surviving construction archive of the camp itself.

The chemistry the deniers want to invoke

The technical wing of the denial movement, drawing on the Leuchter Report and on the work of Germar Rudolf, has argued that the killing chambers cannot have been used for HCN at the concentrations required because the walls would show much higher residual cyanide compounds, in the form of iron blue (Prussian blue, ferric ferrocyanide), than they appear to. The argument cites the visible blue staining on the walls of the delousing chambers, where Prussian blue compounds had indeed formed over many years of repeated exposure, and contrasts it with the absence of comparable staining in the killing chambers. The argument is wrong on two grounds. First, the formation of Prussian blue from HCN exposure is unpredictable and depends on humidity, temperature, iron content of the wall material, exposure duration and many other variables; its absence on a given wall does not indicate absence of HCN exposure. Delousing chambers, with continuous low-level exposure for years, formed Prussian blue; killing chambers, with shorter intense exposures separated by ventilation cycles and (in the case of crematoria II and III) demolition forty years before any sample was taken, did not necessarily.

Second, the proper test is for cyanide reaction products in the surface microns of the wall material, not for visible staining. The Polish forensic study by Markiewicz and others (1990 to 1994) found such products in the killing-chamber samples at concentrations consistent with mass killing use. The chemistry was settled by professional forensic chemists working in a national institute of forensic research; it is not in serious scientific dispute.

Why the claim is harmful

The claim is harmful because it leans on a true fact (Zyklon B was used for delousing) to imply a false conclusion (it was not also used for killing). The deceptive move is the implication that a substance can have only one use, which is plainly absurd in any other context (electricity is used to heat houses and to execute prisoners; nobody argues from this that one of these uses must be fictional). The killing use of Zyklon B at Auschwitz, Majdanek and Stutthof is documented in the construction files of the camps, in the requisition records of the Degesch firm, in the surviving SS testimony, in the perpetrator memoirs, in the Sonderkommando accounts, and in the forensic chemistry of the surviving sites. The delousing use is a wholly separate documentary trail, in different buildings, with different equipment, leaving different physical traces.

Which buildings at Auschwitz were the delousing chambers? Which were the killing chambers? What construction documents distinguish them, and where can those documents be read?

See also

• The Stutthof and Baltic Marches
• IG Farben
• The Leuchter Report Proved No Gas Chambers
• The Nuremberg Trials

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Sources

• Degesch (Deutsche Gesellschaft für Schädlingsbekämpfung), commercial correspondence with the SS Wirtschafts-Verwaltungshauptamt, 1942 to 1944, on the modification of the Auschwitz-specification Zyklon B to omit the warning agent, in Trials of War Criminals Before the Nuremberg Military Tribunals, vol. 8, the IG Farben Trial, US Government Printing Office, 1952
• Zentralbauleitung der Waffen-SS und Polizei Auschwitz, construction files distinguishing the delousing chambers (BW 5a, BW 5b, Block 1 BIa) from the killing chambers (crematoria II, III, IV, V), Russian State Military Archive, Moscow, fond 502, with copies at Auschwitz-Birkenau State Museum
• Jean-Claude Pressac, Auschwitz: Technique and Operation of the Gas Chambers, Beate Klarsfeld Foundation, 1989, with full reproduction of the relevant construction drawings and parallel descriptions of the delousing and killing facilities
• Jean-Claude Pressac, Les Crématoires d’Auschwitz: La Machinerie du Meurtre de Masse, Editions du CNRS, 1993
• Robert Jan van Pelt, The Case for Auschwitz: Evidence from the Irving Trial, Indiana University Press, 2002
• Mr Justice Charles Gray, judgment in David Irving v. Penguin Books and Deborah Lipstadt, Royal Courts of Justice, 11 April 2000, sections on the killing-versus-delousing distinction
• Jan Markiewicz, Wojciech Gubała and Jerzy Łabędź, “A Study of the Cyanide Compounds Content in the Walls of the Gas Chambers in the Former Auschwitz and Birkenau Concentration Camps”, in Z Zagadnień Sądowych, 30, 1994
• Rudolf Höss, Kommandant in Auschwitz, edited by Martin Broszat, Deutsche Verlags-Anstalt, 1958, on the Zyklon B selection and use
• Pery Broad, “Reminiscences”, in Jadwiga Bezwińska and Danuta Czech (eds.), KL Auschwitz Seen by the SS, Auschwitz-Birkenau State Museum, 1972
• Peter Hayes, Industry and Ideology: IG Farben in the Nazi Era, second edition, Cambridge University Press, 2000, on the Degesch supply chain
• Auschwitz-Birkenau State Museum, “Killing Methods: Zyklon B”, https://www.auschwitz.org
• USHMM Holocaust Encyclopedia, “Gassing Operations” and “Zyklon B”, https://encyclopedia.ushmm.org