Zyklon B was originally developed to kill pests. By the early 1940s, it was being used to kill people. This highly poisonous gas, designed for fumigating cargo and buildings, became a core instrument of genocide during the Holocaust. More than one million people, mostly Jews, were murdered with Zyklon B in sealed gas chambers across Nazi extermination camps, particularly at Auschwitz-Birkenau.
Its use marked a turning point in the Nazi regime's drive to industrialize mass murder. This article explains what Zyklon B is, how it works, how it was introduced into the machinery of genocide, and what its legacy means for science, ethics, and historical memory.
Understanding Zyklon B Gas Nazi Quest for Efficient Mass Killing Implementation in Extermination Camps The Role of Zyklon B in Holocaust Mass Murder The Lethal Chemistry: How Zyklon B Gas Kills Production and Supply Chain Psychological Effects on Perpetrators Aftermath & Legacy Lessons and Modern RelevanceTable of Contents
Understanding Zyklon B Gas
To understand how Zyklon B became one of the most infamous chemical agents in human history, it is important to begin with its technical purpose and composition. Long before it entered the gas chamber facilities of Nazi concentration camps, it was used in agriculture, shipping, and sanitation. It's later weaponization by the SS did not require a new invention, only a decision to turn an existing substance against people.
What is Zyklon B?
Zyklon B was the brand name for a cyanide-based insecticide, developed in the early 1920s by Deutsche Gesellschaft für Schädlingsbekämpfung mbH (Degesch). Its active ingredient was hydrogen cyanide (HCN), also known as prussic acid. The gas was absorbed into pellets or discs made of diatomaceous earth and mixed with a stabilizer, then sealed in airtight metal canisters. Upon exposure to air, especially in warmer environments, the Zyklon B pellets released hydrogen cyanide gas rapidly.
Early commercial versions included a warning irritant to alert handlers. However, during the Holocaust, Nazi officials ordered the removal of the irritant to prevent victims from detecting the poisonous gas during gassings. When vaporized in sealed spaces, such as gas chambers, Zyklon B interfered with cellular respiration, leading to rapid death.
Origins as a Pesticide
Zyklon B was developed by German chemists at Degesch, with backing from IG Farben affiliates such as BASF and Degussa. Its original purpose was to control lice and pests in warehouses, ships, clothing, and barracks. The name Zyklon B gained widespread acceptance as an efficient fumigant for agricultural and public health use.
In the 1920s, the U.S. Public Health Service used hydrogen cyanide to disinfect belongings at the Mexican border. Zyklon B used as a pesticide was marketed as a reliable grain-saving and anti-typhus agent. Its transformation into a weapon of mass murder came much later, under Nazi rule.
Chemical Composition and Properties
Hydrogen cyanide is a volatile, colorless to pale-blue liquid, sometimes with a faint almond odor detectable only by a portion of the population. HCN binds to the enzyme cytochrome c oxidase in human cells, blocking oxygen use and halting the production of adenosine triphosphate (ATP). This leads to cellular suffocation despite the presence of oxygen in the blood. It acts quickly and lethally, making it effective against both insects and humans in high enough concentrations.
Nazi Quest for Efficient Mass Killing
The Nazi regime did not begin with gas chambers. Its path to mass murder started with discrimination, escalated through organized violence, and eventually turned toward chemical extermination as a logistical solution. As the scope of the Final Solution expanded, Nazi officials sought methods that would be faster, less visible, and easier to scale. Their choices were shaped by earlier programs, battlefield tactics, and a desire to streamline killing into routine.
From Persecution to Genocide
The Nazi regime's "Final Solution" required methods to kill on a massive scale while maintaining secrecy. Shooting operations by the Einsatzgruppen in 1941 were slow, logistically complex, and psychologically difficult for the perpetrators. Nazi officials began exploring chemical means to industrialize the murder process.
Euthanasia Program and Early Experiments (1939-41)
Gas chamber at Majdanek concentration camp near Lublin
Before Zyklon B was deployed, Nazi doctors had already used carbon monoxide in six euthanasia centers across Germany and Austria. These centers, Hadamar, Hartheim, Grafeneck, Sonnenstein, Bernburg, and Brandenburg, used sealed rooms disguised as showers. As part of the euthanasia program, roughly 70,000 disabled and mentally ill individuals were murdered. Personnel and techniques developed in this program were later transferred to extermination camps.
Gas Vans and Early Experiments (late 1941)
In 1941, Einsatzgruppen began using mobile gas vans to kill Jews in occupied territories. The gas vans diverted engine exhaust into sealed compartments, suffocating those inside with carbon monoxide gas. Though deployed in places like Chełmno, these methods were still too slow and limited for the Nazis' extermination goals.
Turning to Zyklon B Gas
In September 1941, following the invasion of the Soviet Union, SS officials, including Adolf Eichmann, considered Zyklon B, which was already stocked in Nazi concentration camps for delousing. On September 3, 1941, Karl Fritzsch tested it on over 600 Soviet prisoners of war and 250 Polish inmates in the basement of Block 11 at Auschwitz.
The victims died within minutes. The test convinced camp commandant of Auschwitz Rudolf Höss and other leaders that Zyklon B was more efficient than bullets or carbon monoxide. It became the primary method of genocide in several concentration camps like Auschwitz.
Implementation in Extermination Camps
Sites of Nazi Concentration Camps
Once Zyklon B was adopted as a method of mass killing, the Nazis moved quickly to formalize its use across designated extermination sites. These were not improvised locations; they were designed or modified specifically to murder large numbers of people in gas chambers. Among these, Auschwitz-Birkenau became the central killing ground. Other camps followed with their adaptations, but the infrastructure, routines, and chemical logistics all followed a chilling pattern of efficiency.
Auschwitz-Birkenau Gas Chambers
Auschwitz's first gas chamber was in the basement of Crematorium I, with a capacity of around 700 victims. In early 1942, two cottages at Auschwitz II-Birkenau, Bunker 1 and Bunker 2, were converted into gas chambers. By 1943, purpose-built crematoria II through V were operational, each with underground gas chambers and advanced ventilation systems. These facilities could kill up to 2,000 people in gas per gassing.
During the peak in mid-1944, approximately 6,000 Jews were murdered daily at Auschwitz-Birkenau. The total victims numbered approximately 1.1 million people, most of them Jews, killed using stationary gas chambers filled with Zyklon B.
Auschwitz Birkenau camp
Majdanek Concentration Camp
Located near Lublin, Majdanek was initially a labor camp before being equipped with Zyklon B gas chambers. Between 1942 and 1943, thousands of Jews were killed there using the lethal gas. When the Soviets liberated Majdanek in 1944, they discovered intact gas chambers and labeled poison gas canisters, among the first physical proofs shown to the world.
Other Holocaust Sites
Treblinka, Sobibor, and Belzec were Operation Reinhard extermination camps, primarily using used carbon monoxide from engines rather than Zyklon B. Chełmno also used gas vans with engine exhaust. Some smaller death camps, such as Mauthausen, Stutthof, and Dachau, had small Zyklon B chambers for mass murder at Auschwitz and other locations.
The Role of Zyklon B in Holocaust Mass Murder
By 1942, Zyklon B was used as the primary means of mass murder in concentration camps like Auschwitz and Majdanek. Its use was not improvised or occasional; it was systematic, planned, and central to the machinery of genocide. The procedures surrounding each gassing were designed to maintain control, reduce resistance, and carry out death on a schedule.
Understanding how the gas used was deployed, how victims were treated, and what followed each killing helps reveal the full horror of how industrialized murder was carried out.
Gassing Procedure and Victims' Experience
From the moment transports arrived, deception guided every step. Prisoners were told they were going for medical inspections or showers. Families were kept together. Luggage was labeled to suggest it would be returned. Those deemed unfit for labor, like children, the elderly, and the ill, were led calmly toward the gas chambers.
The buildings resembled communal washrooms, complete with benches, hooks for clothing, and false showerheads. Victims were ordered to undress, and their hair was often cut under the pretext of disinfection.
Once sealed inside, an SS officer wearing gas masks dropped Zyklon B pellets through ceiling or wall openings. The warm, overcrowded space triggered rapid vaporization. The hydrogen cyanide attacked the body's ability to use oxygen. Within minutes, those closest to the vents collapsed. People pushed toward the doors or climbed above others for air. Large numbers of Jews and other victims screamed until silence came in fifteen to twenty minutes. The chamber was then aired out. Another group was already waiting.
Impact on Victims
Symptoms included suffocation, frothing at the mouth, bleeding, and convulsions. Victims often climbed atop one another in a desperate attempt to escape. Bodies were discovered in tangled piles. Skin frequently appeared pink, red, or bluish due to cyanide poisoning from the poisonous gas used.
Aftermath and Body Disposal
Once the gas dissipated, Jewish prisoners assigned to Sonderkommando units entered the chamber wearing masks. They removed bodies, shaved hair, extracted gold teeth, and carried the corpses to crematoria or burning pits. Ashes were dumped, and the chambers were cleaned for the next group. Million people in gas chambers died through this systematic process of extermination.
The Lethal Chemistry: How Zyklon B Gas Kills
Zyklon B did not rely on brute force. Its power came from a chemical reaction that disrupted the most basic function of life: the ability of cells to use oxygen. The process was silent, invisible, and devastating. To understand how this gas killed so quickly, it is necessary to look at what hydrogen cyanide does inside the body and why even small doses were enough to cause mass death.
Hydrogen Cyanide's Effect
Inhaled hydrogen cyanide enters the bloodstream and binds to iron within cytochrome c oxidase in the mitochondria. This blocks the electron transport chain, halting ATP production. Cells, especially in the brain and heart, suffocate despite oxygen being present in the blood.
Rapid Death in High Concentrations
As little as 70 milligrams of hydrogen cyanide can kill an adult in minutes. Concentrations of around 300 parts per million can be lethal within 10 to 15 minutes. In Nazi gas chambers, doses exceeded this level, resulting in mass death within a short period.
Visible Symptoms
Victims often exhibited pink or red skin due to oxygen-rich blood that cells could not use. Other symptoms included blue or green mottling, bleeding from the mouth or nose, and loss of control over bodily functions. Ironically, higher concentrations and longer exposures were needed to kill lice than humans.
Production and Supply Chain
The use of Zyklon B on such a large scale required more than a deadly formula. It depended on a reliable network of manufacturers, distributors, and logistics partners who could supply the gas to extermination camps efficiently and without scrutiny. This supply chain involved several private companies, many of which operated under government contracts or worked closely with the SS.
Manufacturers
Degesch, part-owned by IG Farben, held the patent and trademark for the brand name Zyklon. It was produced by Dessauer Werke and Kaliwerke Kolin. Distribution in eastern Germany and occupied areas was managed by Tesch & Stabenow (Testa), run by Bruno Tesch in Hamburg. Heerdt-Lingler (Heli) managed western and southern German sales.
The gas was stored and transported in hermetically sealed canisters, with each canister containing pellets that would release hydrogen cyanide when exposed to air. These containers were used only by trained personnel under normal circumstances, but during the Holocaust, they became instruments of genocide.
Wartime Sales and SS Procurement
In April 1941, the SS became authorized users of Zyklon B, bypassing civilian regulation. Between 1942 and 1944, sales of Zyklon B reached 729 tonnes, with about 56 tonnes (approximately 8%) shipped to Nazi concentration camps. Auschwitz received 23.8 tonnes, only 6 of which were officially designated for fumigation. The rest contributed to mass murder, demonstrating the gas's lethal efficiency.
Companies like Tesch & Stabenow supplied Zyklon B to the SS for what they claimed were delousing purposes, but evidence suggests they knew about its use for mass killing.
Key Individuals
Bruno Tesch, Karl Weinbacher, Gerhard Peters, Carl Wurster, Fritz Haber
Several individuals played direct roles in providing Zyklon B for mass murder:
- Bruno Tesch, co-owner of Tesch & Stabenow, knowingly supplied Zyklon B to the SS and was later hanged on May 16, 1946
- Karl Weinbacher, his deputy, was also found guilty and executed in 1946 during the Hamburg Zyklon B Trial
- Gerhard Peters, managing director of Degesch, was convicted for his involvement but was later released on appeal
- Carl Wurster and other IG Farben executives denied responsibility yet benefited from the profits generated by the sales
- Fritz Haber, though not directly involved in Holocaust applications, had earlier worked at the Kaiser Wilhelm Institute for Physical Chemistry and Electrochemistry on chemical weapons development
Psychological Effects on Perpetrators
Some SS officers experienced trauma and moral conflict, though others remained ideologically committed. Many coped by dehumanizing victims and normalizing routine violence. Alcohol consumption was widespread, and some recorded nightmares or postwar psychological issues. The toll on Jewish Sonderkommando members was even more devastating, with long-lasting emotional scars from witnessing million people were killed in the gas chambers.
Aftermath & Legacy
When the camps were liberated in 1944 and 1945, Allied forces encountered evidence that confirmed the scale and method of the killings. Gas chambers stood intact. Canisters of Zyklon B were found in storage rooms and next to crematoria. Survivor testimonies and physical remnants provided undeniable proof of what had taken place.
What followed was a reckoning in courtrooms, in industry, and in memory that shaped how the world would remember the Holocaust and respond to chemical weapons.
Discovery by the Allies
When Allied forces liberated camps in 1944 and 1945, they found intact gas chambers, labeled poison gas canisters, and surviving prisoners. Photographs and physical evidence, especially from Auschwitz and Majdanek, confirmed the widespread use of Zyklon B was used for systematic gassing.
Legal Consequences and Trials
The Nuremberg International Military Tribunal (1945–1946) held top Nazi officials accountable during the Nuremberg trials. The Hamburg Zyklon B Trial condemned Bruno Tesch and Karl Weinbacher for their role in supplying the lethal gas. The IG Farben Trial (1947–1948) yielded mixed verdicts. While some industrialists were imprisoned, others escaped responsibility.
Rudolf Höss, the commandant of Auschwitz, testified about the use of Zyklon B for mass murder before being executed in 1946. His testimony provided crucial evidence about how the gas was deployed in the extermination process.
Bans and Regulations
The brand name Zyklon B was discontinued after the war. Use of hydrogen cyanide in pesticides was banned or heavily restricted, especially in countries affected by the Holocaust. New fumigants were developed, and strict safety protocols were implemented to prevent future misuse. The connection to Nazi persecution made any commercial use of the name Zyklon B impossible.
Survivor Testimonies
First-hand accounts provide irreplaceable evidence of the Holocaust. Survivors described the terror, the deceit, the symptoms, and the aftermath of the gas chambers. Their voices remain vital in educating future generations and preventing denial about how Zyklon B was used for genocide.
Historical Memory
Zyklon B canisters are displayed in Holocaust museums such as the Auschwitz-Birkenau State Museum. The name Zyklon B has become an enduring symbol of genocide and industrialized evil in Nazi Germany. It evokes immediate association with one of history's darkest atrocities, representing how ordinary commercial products can be perverted for mass murder.
Lessons and Modern Relevance
The story of Zyklon B does not end with the fall of Nazi Germany. Its legacy continues to influence how societies regulate science, respond to atrocities, and protect civilian life. The Holocaust forced the world to confront the consequences of unchecked power paired with technical knowledge.
In the decades since, Zyklon B has become a symbol not only of genocide but also of the urgent need for safeguards against the use of chemical agents in any context.
Chemical Weapons in Warfare
Zyklon B highlights the catastrophic potential of chemical agents used against civilians. Its legacy helped push forward international bans, beginning with the Geneva Protocol of 1925 and culminating in the Chemical Weapons Convention of 1993. The memory of mass murder in the gas chambers serves as a warning against chemical warfare.
Importance of Protective Measures
Exposure to gas in confined spaces is nearly always fatal without protection. SS officers wore gas masks during the killings. Today, military and emergency responders are trained in handling toxic agents with proper equipment to avoid mass casualties from poisonous gases.
Modern CBRN Protection Against Chemical Warfare Agents
The lethal efficiency of Zyklon B demonstrates why professional-grade CBRN gas masks and hazmat suits are essential for protection against chemical warfare agents (CWAs). Modern CBRN equipment is specifically designed to filter hydrogen cyanide and similar chemical threats that can prove fatal within minutes.
Given that concentrations as low as 300 parts per million can kill in 10-15 minutes, proper protective equipment provides the critical barrier between exposure and death that chemical agents like Zyklon B demand.
"Never Again" — Vigilance Through Education
Zyklon B's misuse serves as a warning against technological abuse driven by genocidal ideologies. It also illustrates how something mundane—a pesticide—became a genocide engine. Education ensures continued awareness and resistance against similar abuses.
Lessons from History
The Holocaust and Zyklon B's role in it show the dangers of unchecked hatred and dehumanization. Historical awareness strengthens the defense of human rights, encourages empathy, and reinforces the need to preserve accurate history about how Nazi concentration camps operated and how industrial processes were perverted for mass killing.
Conclusion
Zyklon B will always be remembered as the gas of the Holocaust. It represents a tragic example of how scientific progress can be hijacked for mass destruction. Chemists, businessmen, and Nazi leaders together created a chain of complicity that ended in mass murder. More than a million lives were extinguished, leaving an indelible scar on humanity.
The legacy of Zyklon B supports ongoing bans on chemical weapons and insists on ethical control over dangerous technologies. Honoring the victims means preserving historical truth and educating every new generation about the dangers of letting hatred and ideology override human decency.
“Never Again” is a promise: to remember, to protect, and to stay alert against threats, even those that arrive in silence. To understand the past is to prepare for the future, and Mira Safety provides professional-grade protective equipment for those who take chemical threats seriously.
The story of Zyklon B serves as a permanent reminder that the price of freedom and human dignity is eternal vigilance against those who would use technology and industry to commit mass atrocities.