Chemical weapons

As a means of mass destruction, chemical weapons claim many fatalities and injured but are relatively cheap to produce. While chemical weapons were first developed and used during World War I, their use continued in World War II, the Vietnam War and the first Gulf War (1980 to 1988).

They were 'discovered' by German chemist Fritz Haber, who had been the director of the Department of Physical Chemistry in Berlin-Dahlem since 1911. He held this post until he was removed from office by the Nazis in 1933 because he was a Jew. For his services to agricultural chemistry (he invented the first artificial fertilizer), Haber was awarded the Nobel Prize in Chemistry in 1918. In 1920, he explained his military research as follows: "The advantage of gas ammunition is particularly high in trench warfare, as the poisonous gas reaches behind each earth wall, nook and cranny, where the flying shrapnel cannot access". (own translation).

Other scientists were a lot more critical of the topic. They pointed to the personal and social responsibility of chemists, physicists and biologists, in particular when the military use of their knowledge was concerned. The debates on the relationship between ethics and science still continue today.

Chemical weapons consist of a chemical agent and a delivery system that propels this agent to its target. Chemical agents can choke, disable or poison. Some toxins damage the blood, the skin, the lungs or the nerves. The first chemical weapons simply consisted of toxic gases that were known from the production of chemicals, such as chlorine or phosgene. Later, new agents were produced synthetically, purely for the purpose of using them for military warfare. Means of delivery are mines, hand grenades, grenades, bombs, spray tanks or missile warheads. In World War I, these agents were spread as gas, this is why their common name is poisonous gas. But as gas disperses quickly, the military later used the agent in aerosols. An aerosol consists of a multitude of microscopically small droplets that spread like mist.

Military use of chemical weapons

To get a picture of the hazardousness of chemical weapons, it makes sense to take a good look at their military uses. In principle, chemical weapons are so dangerous because of their so-called toxicity. Toxicity indicates how lethal such a weapon is for human beings. But there is no exact measurement as people react differently to toxins due, for instance, to their individual body weight. This is why a greater amount of a toxin is needed to kill an adult than to kill a child.

As a general indicator of the specific toxicity of a substance, the statistic measure of LD50 "median lethal dose" was introduced. It is the dose that kills a human being with a likelihood of 50 per cent. With the help of LD50, the lethality of different agents can thus be compared. When chemical weapons are used, they can be swept away by the wind very quickly. This is why the military also wanted to know how long a person would have to be exposed to a toxin to die of this exposure. The measure for this is the “median lethal vapour or aerosol concentration”, LCt50. It indicates how high the concentration of a substance must be in a cubic metre of air to kill a human being with a 50 per cent probability over the test duration of one minute. Here, the toxin can be absorbed through the skin (percutaneously) or orally. Even if a soldier has absorbed a smaller dose, he will become ill and will be unable to fight. This is why this measure is also important for the military. It is called “median incapacitating concentration”( lCt50).

warfare agent




(mg min/m3)8


(mg min/m3)8













hydrocyanic acid3








mustard gas5




















Notes: (1) tear gas, (2) psychopharmacological agent, (3) blood agent, (4) choking (pulmonary) agent (5) blistering agent (6) nerve agent (7) mg per kg body weight (8) mg per minute per m3 air (9) here: absolutely deadly dose (LD100)

Based on this information, those planning a war can determine the amount of chemical warfare agents used in an attack. At the same time, they need to take environmental factors into consideration, as the gas used can be swept away by the wind. These conditions also determine when an area can be accessed again without the danger of being exposed to these substances. Another factor is the fact that these toxins, once exposed to the UV radiation of the sun, break down at different speeds.

warefare agent

+ 10oC

+ 15oC
light breeze

- 10oC
no wind
snow cover



1 - 2 hrs

6 hrs to a few days

hydrocyanic acid

a few minutes

a few minutes

1 - 4 hrs


a few minutes

a few minutes

15 minutes to 4 hrs

mustard gas

12 - 48 hrs

2 - 7 days

2 - 8 weeks


15 minutes to 1 hour

15 minutes to 1 hour

1 - 2 days


3 - 36 hrs

2.5 - 5 days

1 - 6 weeks


1 - 12 hrs

3 - 21 days

1 - 16 weeks

In practice, the highest concentration of the chemical agents could be found on trees, rooftops and grassland. Despite the high toxicity of the substances, an attack was only 'successful' when many tonnes of the agent were deployed at the same time. Should the wind turn, any use of such agents would also present serious risks for their soldiers.

As the stockpiling of 'live' chemical weapons alone bears significant risks, the United States developed binary precursors for artillery shells and bombs. These consist of two less toxic substances that are physically separated within the weapon and that only react with each other upon the deployment of the weapon, creating a deadly mix. Examples of a binary chemical weapon are the 155mm artillery shell M687 (sarin) and the BLU-80/B Bigeye glide bomb (VX).

A very controversial kind of weapon

Chemical weapons have been controversial even amongst the military right from their inception—a rather uncommon phenomenon. Those who advocated the use of chemical weapons were of the opinion that chemical weapons would be able to kill large amounts of enemy soldiers across considerable distances. Those who were sceptical of these weapons argued that they be difficult to deploy at a tactical level, had little effect and could endanger their troops. Front-line soldiers of all armies are particularly wary of chemical weapons since their first deployment in World War I. Many gas casualties battled death for multiple days until they finally choked. Survivors often had to live with permanent damages from which they suffered their entire lives: they were blind, had chemical burns on their skins, damaged lung tissue or suffered from cancer.

As a matter of course, the military did invent not only chemical weapons but also technical means to protect against them. Today, protective equipment for soldiers is well advanced so that a gas attack hardly results in any strategic or tactical advantage.

These military–strategic limitations also led to the fact that chemical weapons—as the very first weapons of mass destruction—were subject to a treaty that outlaws their production, stockpiling and use. The Chemical Weapons Convention (CWC) entered into force in 1997. Still, even today, one cannot totally exclude an attack with chemical weapons, be it a terrorist attack or a last desperate attempt by an uninhibited dictator in view of his looming defeat in a civil war.

Sources and further information:

  • Angerer, Jo (1985): Chemische Waffen in Deutschland – Mißbrauch einer Wissenschaft, Darmstadt.
  • Brauch, Hans Günter und Alfred Schrempf (1982): Giftgas in der Bundesrepublik – Chemische und biologische Waffen, Frankfurt.
  • Dosch, Werner und Peter Herrlich (Hrsg.)(1985): Ächtung der Giftwaffen – Naturwissenschaftler warnen vor Chemischen und Biologischen Waffen, Frankfurt.
  • Harris, Robert und Jeremy Paxman (2002). A Higher Form of Killing: The Secret History of Chemical and Biological Warfare.
  • N.N. (2012): Chemical weapon, Wikipedia.

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