Updated: Aug 23
Chemical weapons require a relatively low investment, can cause severe psychological and physical effects and are agents of disruption.
Modern chemical weapons were introduced during World War I in an effort to reduce the deadlock of trench warfare. But they are subject to topography and weather patterns. As munitions have become more precise, their tactical advantage is being eroded. Today, they horrify more than they contribute to victories on the ground.
Their indiscriminate nature and unpredictability, coupled with the sometimes-gruesome effects they have make them effective weapons of fear. Below are five of the worst chemical weapons:
VX belongs to organophosphorus compounds and is classified as a nerve agent because it affects the transmission of nerve impulses in the nervous system. It is odorless and tasteless in its pure form, and appears as a brownish oily liquid.
Developed in the UK in the early 1950s, VX is particularly potent because it’s a persistent agent: Once it’s released into the atmosphere it’s slow to evaporate. Under regular weather conditions, VX can persist for days on surfaces, while it can last for months in very cold conditions.
VX vapor is heavier than air, which means that when released, it will sink to low-lying areas and create a greater exposure hazard there. Such characteristics make VX potentially useful as an area-denial weapon.
VX is also a fast-acting agent. Symptoms can appear only seconds after exposure. They include salivation, constriction of the pupils and tightness in the chest.
As with other nerve agents, VX works by affecting the enzyme (acetylcholinesterase) that acts as the body’s ‘off switch’ for glands and muscles.
With the enzyme blocked, molecules constantly stimulate the muscles. As the muscles spasm, they tire. Death is caused by asphyxiation or heart failure. While it is possible to recover from exposure, tiny amounts of the agent can be lethal.
Sarin (also known as GB) is a volatile but toxic nerve agent.
A single drop the size of the head of a pin is enough to kill an adult human rapidly.
It is a colorless and odorless liquid at room temperature, but evaporates rapidly when heated.
After release, Sarin will spread into the environment rapidly and present an immediate but short-lived threat.
Similar to VX, symptoms include headaches, salivation and secretion of tears, followed by gradual paralysis of the muscles” and possible death.
The quality of the agent also matters. Sarin (and VX) is susceptible to degradation, especially if it isn’t pure.
Also known as sulphur mustard, this agent gets its name from its trademark rotten mustard or garlic and onion odor.
It belongs to the group of blister agents (or vesicants) that work by targeting the eyes, respiratory tract and skin, first as an irritant and then as poison for the body’s cells.
It’s particularly grisly and slow acting. When skin is exposed to it, it reddens and burns for a few hours before large blisters appear and cause severe scarring and pain. Eyes will swell, tear and possibly go blind a few hours after exposure, and when inhaled or ingested, victims will experience sneezing, hoarseness, coughing up blood, abdominal pain and vomiting.
Along with its gruesome physical effects, mustard gas is chemically stable and very persistent. Its fumes are more than six times heavier than air and stay near the ground for several hours. This made it particularly useful for filling and contaminating enemy trenches.
It remains toxic for a day or two under average weather conditions and from weeks to months under very cold conditions.
What’s more, persistency can be increased by “thickening” the agent: dissolving it in nonvolatile solvents. It poses significant problems for protection, decontamination and treatment.
Mustard gas is relatively easy to produce, with readily available early precursors. It also retains its quality for a long time.
For example, German munitions used in the world wars are still periodically dug up in Belgium and the agents are barely degraded. Mustard gas forces enemy troops to wear full protective equipment thereby degrading efficiency. But the protective gear doesn’t always work. Gas masks, for example, are often not enough.
During the Iran-Iraq war, mustard gas seeped through the masks as young Iranians’ beards (grown for religious purposes) broke the seal of the mask. Mustard gas also easily penetrates through clothes, shoes or other materials.
To this day, phosgene is considered one of the most dangerous existing chemical weapons.
It was first used in combination with chlorine gas on December 19, 1915, when Germany dropped 88 tons of the gas on British troops, causing 120 deaths and 1069 casualties.
During World War I, it accounted for 80 percent of all chemical fatalities. Although it is not as toxic as sarin or VX, it’s much easier to make, which makes it more accessible to all.
Phosgene is an industrial chemical used in the fabrication of plastics and pesticides. It’s made by exposing chlorinated hydrocarbon compounds to high temperatures. In other words, it can be made at home by exposing chloroform to UV-light for a few days.
Phosgene is a choking agent that works by attacking lung tissue. Initial likely symptoms of coughing, choking, tightness in the chest, nausea, and occasionally vomiting occur minutes after exposure.
This may seem quick but it actually means that victims continue to inhale it until symptoms become apparent. Delayed effects can occur up to 48 hours after exposure.
At room temperature and pressure, it’s an almost colorless gas that smells of freshly cut grass in low concentrations. It’s nonflammable and evaporates when heated above eight degrees, which makes it volatile. But its vapor density is more than three times that of air, which means that it’ll linger in low-lying areas, including trenches.
Chlorine is a readily available industrial chemical with many peaceful uses, including as bleach in paper and cloth, to make pesticides, rubber, and solvents and to kill bacteria in drinking water and swimming pools.
It’s the perfect example of a problematic dual-use chemical. Chlorine did not figure in Assad’s initial stockpile declaration in October and was not removed with the rest of Syria’s chemical weapons last month.
Chlorine gas is yellow-green colored and has a strong smell similar to bleach. Like phosgene, it is a choking agent, which obstructs breathing and damages tissues in the body. It can easily be pressurized and cooled to liquid state so that it can be shipped and stored.
Chlorine spreads quickly and stays close to the ground because it is heavier than air. Though it is less lethal than other chemical agents, chlorine is dangerous because it’s easy to manufacture and disguise.