Zyklon Introduction Columns

by Jamie McCarthy
and Mark Van Alstine


At Auschwitz-Birkenau, in the gas chambers of crematoria II and III, Zyklon-B was poured in through holes in the roof. After early experiments with this poison, the camp staff had learned that it was important to allow the pellets of Zyklon to be removed after the victims' death, and also to spread them to increase the speed of outgassing.

The solution to these problems was a wire mesh column, which ran from the floor up through the roof. An SS man, wearing a gas mask and standing on the roof, would pour the pellets into the top of the column and place a wooden cover over it. The pellets fell into an inner wire mesh basket, which held them as they released their poison into the gas chamber.

After the mass murder was complete, the cover was opened, the basket was pulled up, and the Zyklon expelled the remainder of its poison harmlessly into the open air. Meanwhile, the ventilation of the gas chamber and the cremation of the corpses could begin.

These columns are listed in the inventory of crematorium II, March 31, 1943, as "wire-mesh insertion devices" (Drahtnetzeinschiebvorrichtung) with "wooden covers" (Holzblenden).


Below is a schematic cross-section of the introduction column, viewed from the side. Each of the measurements has been collected from various eyewitness testimonial sources; they have been synthesized into this drawing. The measurements shown are the best approximations of those sources, but should not be considered to be exact to the centimeter.

Cross-section, introduction column

Sources: Gutman, Yisrael, and Michael Berenbaum, Anatomy of the Auschwitz Death Camp, 1994; Pressac, Jean-Claude, Auschwitz: Technique and Operation of the Gas Chambers, Beate Klarsfeld Foundation, New York, 1989.


Michal Kula, a former prisoner who worked in the metalworking shop of the Auschwitz-Birkenau camp, gave a deposition describing the introduction columns in June 1945. Below is a sketch illustrating what he described in that deposition. The captions are from Jean-Claude Pressac's book Auschwitz: Technique and Operation of the Gas Chambers, which was originally published in French; the translations are below.

This sketch shows the smaller "wire basket," above the column into which it was inserted. This "movable part" is what actually held the pellets of Zyklon as they gave off the poison gas, and is what was pulled up once the gassing operation was complete.

Sketch of introduction column by Michal Kula


Coiffe en tôle
Metal cap
Intervalle separant le tube en tôle du 3ème tamis: 25 mm
Space between the metal tube and the third lattice: 25 mm
Troisième tamis intérieur à maille de 1 mm de côté
Third, innermost, lattice of 1 mm mesh
Tube en fine tôle zinguée de 15 cm de côté
Thin galvanized metal tube, 15 cm square
Pièce de métal reliant les 1er et 2ème tamis
Metal strip joining the first and second lattices
Premier tamis extérieur en fil de 3 mm de diamètre et de maille de 45 mm de côté
First, external, lattice of 3 mm diameter wire, 45 mm mesh
Deuxième tamis intérieur à maille de 25 mm de côté
Second, interior, lattice of 25 mm mesh
3 m environ
Approximately 3 m
Cornières de 50 x 50 x 10 mm
Angle irons, 50 x 50 x 10 mm

Source: Pressac, Jean-Claude, Auschwitz: Technique and Operation of the Gas Chambers, Beate Klarsfeld Foundation, New York, 1989, p. 487.

Erber's Testimony

In 1981, historian Gerald Fleming spoke to former SS-Sergeant Major Josef Houstek, who had changed his name to Josef Erber after serving at Auschwitz. Erber described the columns as appearing slightly different:

In each of these gassing areas [of the crematoria [II and III] in Birkenau] were two ducts: in each duct, four iron pipes ran from the floor to the roof. These were encased with steel mesh wire and inside there was a tin canister with a low rim. Attached to this tin was a wire by which it could be pulled up to the roof. When the lids were lifted, one could pull up the tin canister and shake the gas crystals into it. Then the canister was lowered, and the lid closed. 6

6. Prisoner Josef Erber to author, 14 September 1981.

The "four iron pipes" are presumably the four corners around which the outside mesh was wrapped. The tin canister lowered by a wire may be an earlier, or later, version of the inside "wire basket" described by Kula.

Source: Fleming, Gerald, Hitler and the Final Solution, 1984, p. 188.

Tauber's Description

Henryk Tauber gave a deposition in May 1945 which included a description of the columns:

The side of these pillars, which went up through the roof, were of heavy wire mesh. Inside this grid, there was another of finer mesh and inside that a third of very fine mesh. Inside this last mesh cage there was a removable can which was pulled out with a wire to recover the pellets from which the gas had evaporated.


The undressing room and the gas chamber were covered first with a concrete slab then with a layer of soil sown with grass. There were four small chimneys, the openings through which the gas was thrown in that rose above the gas chamber.

Source: Pressac, Jean-Claude, op.cit., p. 484.

Aerial View

Allied reconnaissance planes gained the military ability to overfly the Auschwitz area in mid-1944. The nearby IG Farben plant produced synthetic rubber and oil, and was of military interest for that reason, but several photographs were also taken of the Birkenau camp. On August 25, 1944, a plane captured this view of Birkenau, including the gas chambers of crematoria II and III.

On this photograph, crematorium II is in the rectangle at middle-right, and crematorium III is at the lower right. North is to the bottom.

Aerial view, Auschwitz-Birkenau, 1944 August 25

Below, an enlargement of the same photograph shows the building of crematorium II. At bottom, the crematorium chimney casts a long shadow. Extending up (south) from the building is the underground gas chamber, Leichenkeller 1. Four dark patches are visible, corresponding to the four "little chimneys" of the introduction columns.

Aerial view, detail, Auschwitz-Birkenau, 1944 August 25

Source: U.S. National Archives, Record Group 317 - Auschwitz Box Envelope 17 / Security Set - CIA Annotated Negative #17, photograph of August 25, 1944.

Ground View

Below is a ground view of the same crematorium, looking north from its south. On the right is the crematorium building with its chimney visible. Jean-Claude Pressac places the date of this photograph between February 9 and 11, 1943. The building is still being constructed and will not be completed until late March 1943.

The gas chamber Leichenkeller 1, just to the right of the train's smokestack, extends toward the camera and slightly to the right.

Ground view, Krema II at Auschwitz-Birkenau

Below, an enlargement from the same photograph shows the gas chamber. Like the rest of the building, it is under construction. It has not yet been covered with earth, making the "little chimneys" look taller than they would end up being.

Careful photographic analysis has shown that the two dark short vertical shadows, under the middle window in this photo, are the two southernmost "little chimneys." (The dark rectangle to their right appears to be against the wall of the building, behind the gas chamber. It is unknown what the shorter, lighter-gray shadow is to their left. The light vertical lines in front of the gas chamber are fenceposts.) The third "little chimney" is behind the smokestack, and a top corner of the fourth can barely be seen, just to the left of the smokestack, and mostly obscured by the mound of snow-covered earth. From this angle, their placement is staggered due to the east-west alternation.

Ground view, detail, Krema II at Auschwitz-Birkenau

Source: Pressac, Jean-Claude, Auschwitz: Technique and Operation of the Gas Chambers, Beate Klarsfeld Foundation, New York, 1989, p. 340. Cited by Pressac as PMO neg. no. 20995/494, Kamann series. And Keren, Daniel, Jamie McCarthy, and Harry W. Mazal, Holocaust and Genocide Studies, Oxford University Press, Vol. 18, No. 1, Spring 2004, pp. 68ff.: "The Ruins of the Gas Chambers: A Forensic Investigation of Crematoriums at Auschwitz I and Auschwitz-Birkenau."

A Similar Vent

A rare photograph of a similar introduction vent from Majdanek, not Auschwitz, has been preserved. Majdanek was also a camp where mass gassings were performed.

When the Red Army arrived in July 1944 the soldiers found huge warehouses spilling over with goods. They discovered dead bodies and further evidence of a full range of atrocities, which they publicized immediately to the world presses.

(Feig, Konnilyn, Hitler's Death Camps, 1979, p. 330.)

A Soviet army man posed for this photograph, holding the device's cover, standing next to the device itself. It was published in the London press in October 1944. It is unknown how similar this actually looked to the "little chimneys" of Auschwitz-Birkenau.

Majdanek introduction vent

Source: The Illustrated London News, October 14, 1944, p. 442.


Holocaust-deniers reject that these columns even existed. The convergence of this evidence, including the compelling testimonies giving details before corroborating documentary evidence was unearthed, is ignored.

Kula's and Tauber's depositions describing the "wire-mesh insertion devices," decades before the corroborating documentary evidence was discovered in the archives, cannot be explained away. Houstek/Erber's description of the same devices, also before that evidence was discovered, is also a powerful corroboration.

Deniers will likely argue that the minor differences in their descriptions mean we should ignore them. But should we really expect to find identical accounts? The prisoners gave their descriptions months after the fact; the perpetrator, 35 years later. That may account for some of the difference. Just as importantly, we do not know if the Nazis in charge of the gassing operation tried slightly different types of equipment from time to time.

Indeed, if all three descriptions were exactly alike, we might suspect that the later account was copied from the earlier ones. Because they are not, we know that here are three separate eyewitnesses to these items.

Holocaust-deniers reject the validity of the aerial photographs, claiming that the four dark spots on the roof of each gas chamber were retouchings added by the CIA or some other conspiracy. John Ball, who has no expertise in interpreting aerial photographs, suggests either that hypothesis or, alternatively, that the dark spots were flowerpots sitting on each gas chamber.

The objects shown on the roof in the ground photo, say some deniers, are ordinary boxes of construction material.

Deniers also claim that there is no evidence of four holes in the roof of each gas chamber. Because the chambers were dynamited in an attempt to hide evidence of mass murder from the approaching Soviet army, the roofs have collapsed and it is difficult to tell in the rubble what is a hole and what is not. Later this year, an essay on this website will address this question in detail.

Finally, Holocaust-deniers intentionally confuse the solid support columns for the gas chamber roof with the wire-mesh columns. As obvious evidence of their crimes, the latter would have been removed by the Nazis from the gas chambers before they were blown up. Ludicrously, deniers show photos of the solid columns as proof that the wire-mesh columns never existed.

Such feeble attempts to rewrite history do not stand.

Thanks go to Holocaust History Project volunteer Harry Mazal for research assistance.