At least 13 reported incidents of chlorine use occurred in Iraq in 2006-2007. Now there are almost daily reports of chlorine being used in the Middle East, whether in helicopter-delivered “barrel bombs” by the Assad regime against civilians or in improvised devices by ISIS or other Islamists of various types. History and science show us that chlorine is not terribly lethal as a chemical weapon, but does have quite useful attributes for attackers, such as the Assad regime and ISIS, fighting in desperate circumstances.
A few years ago, any serious chemical warfare professional would have said that “Peak Chlorine” was a century ago, in December 1915. The major military manuals and textbooks are dismissive of chlorine as a chemical weapon and mention it as being of historic interest and mostly relevant only to industrial accidents today. The Chemical Weapons Convention (CWC) does not even consider it. However, after a 100-year hiatus, chlorine lives to fight another day in the Middle East.
Chlorine in the Great War
It is instructive to examine the operational record of chlorine on the battlefield and its physical and technical characteristics. Chlorine was first used as a weapon in 1915 at Ypres on the Western Front, but contemplation of its military uses began long before Production of chlorine in liquid or gas form dates from the late 1700s. Chlorine weapons were theoretically discussed since 1862, when New York schoolteacher John Doughty suggested it for use in the American Civil War. Chlorine was not the first chemical weapon used in warfare and Ypres was not the first use of chemical weapons; it was merely the first one that anyone took notice of. There were several other earlier attempts during WWI with other chemical agents, such as tear gases and xylyl bromide, which were completely ineffective and mostly went unnoticed by defenders.
While it did kill and injure people, chlorine was not effective as a lethal battlefield weapon. Claims that thousands of soldiers were killed by chlorine at Ypres are an exaggeration, as France and Britain only report about 16,000 direct fatalities from chemical warfare between them for the entire war. Instead, the key effect of chlorine use at Ypres was the panic and fear it induced in the trenches. Eventually, effective respirators were developed and fielded, from which point the fear was reduced, only to be replaced with performance degradation. Both of these conditions acted as force multipliers.
A few years ago, chemical warfare professionals would have said “Peak Chlorine” was a century ago, in December 1915. However, after a 100-year hiatus, chlorine lives to fight another day in the Middle East.
Wilfred Owen’s WWI poem Dulce Et Decorum Est captures the visceral fear gas causes:
Gas! Gas! Quick, boys! – An ecstasy of fumbling, Fitting the clumsy helmets just in time; But someone still was yelling out and stumbling, And floundring like a man in fire or lime . . . Dim, through the misty panes and thick green light, As under a green sea, I saw him drowning. In all my dreams, before my helpless sight, He plunges at me, guttering, choking, drowning.
Chlorine was not in use for very long. The reasons were numerous. In the early days of chemical warfare, attacking troops could not exploit any tactical gains made by an effective chlorine attack, as unprotected troops could not be expected to advance into the cloud that they had just unleashed upon their enemy. Also, the toxicity of chlorine was relatively low, which meant that a lot of chlorine needed to be used in order to have anything close to a lethal effect. Chlorine lacked an effective means of delivery at any kind of range, as it was not really amenable to dispersal in artillery or mortar shells (some were fielded, but their efficiency was dismal). The usual way to dispense chlorine on the battlefield was by means of a gas cylinder.
The relatively low lethality combined with the gas cylinder delivery mechanism meant that chemical attacks consisted of thousands of pressurized gas cylinders being hauled, generally by hand, to the front lines. The original Ypres chlorine attack used 5,730 gas cylinders. In several instances, the cumbersome movements of gas cylinders were an obvious indicator to the other side that a chemical attack was imminent. The advent of better-suited chemicals (such as phosgene, responsible for at least 80% of the war’s chemical agent fatalities and, later, mustard) meant that chlorine was quickly relegated.
Easily-Manufactured Plausible Deniability
Chlorine is not entirely without benefit as a weapon. It easily manufactured and is available in large quantities as an industrial chemical that will not ring alarm bells with non-proliferation agencies. Chlorine’s irritant effect might make it usable as an improvised “tear gas” substance, used in riot or crowd control or to drive people from confined spaces. It can also provide deniability for attackers, as the toxic effects of chlorine are relatively non-specific (many other chemicals can cause the same basic signs and symptoms) and post-exposure examination of victims is not likely to conclusively indicate that chlorine was the exact culprit. This makes it harder to point fingers at “whodunit” afterwards, as has been the case with several reported chlorine gas incidents in Syria and Iraq.
The non-persistent nature of chlorine gas means that detecting an attack after the fact is very difficult. Unless you are there on the spot with the correct equipment to collect a gas sample, proving chlorine use is problematic. The post-exposure environmental indicators are often quite non-specific. In other words, a positive test for chlorine in some material from the alleged incident scene does not conclusively point to chlorine gas usage, as other sources of chlorination are possible.
Poor Detective Work
In a video by The Telegraph in April 2014, Syrian soil samples were analyzed by Hamish De Bretton Gordon with a hand-held Dräger gas detector. This particular exercise was touted in the media as proof that both chlorine and ammonia had been used in Syria. While chlorine may indeed have been used in the particular incident that Mr. De Bretton Gordon investigated, his exercise with a Dräger gas detector and plastic bags do not constitute proof. Indeed, the conclusion is problematic. It is my opinion that the ammonia allegation is unsupportable.
Chlorine and ammonia are highly reactive when put together. How would such an attack possibly have worked in practice? His particular Dräger detector has published cross-sensitivities for ammonia and chlorine (chlorine gives a very strong response on the ammonia sensor, and ammonia gives a mild response on the chlorine sensor.) So, claiming both based on the same reading is misleading and shows a fundamental misunderstanding of the equipment. The soil sample could easily have been chlorinated by some other means. But would a soil sample doctored with bleach or water from, say, a swimming pool create the same effect? Possibly. Even a plastic bag in the hot sun can give off traces of chlorine depending upon the kind of plastic it was made of.
Chlorine in Syria and Iraq
So, what is going on with the chlorine in Iraq and Syria? Despite the questionable methods used above, there is a strong circumstantial case that chlorine is indeed being used. In the various incidents where chlorine was reportedly used, it is actually difficult to point to many victims who died from chlorine exposure rather than from other means, such as fragmentation injuries or other traumas. Why use such an ineffective weapon? I have four hypotheses, none of which are mutually exclusive:
- The chlorine may be meant to maim, not to kill, by causing widespread lung, skin, and eye injuries that are painful, but not often lethal;
- It could be used like a riot control agent (like CS) to force people outdoors from shelters, bunkers, and buildings, making them more vulnerable to conventional attack;
- It could be used as an attempt to stretch existing conventional weapon stocks due to the degraded industrial base and supply chain. For example, perhaps chlorine gas is being mixed into barrel bombs in order to conserve explosives;
- It could be used as a weapon deliberately to induce fear and terror in a target populace fairly well-habituated to conventional attack after years of war.
As the history of chlorine gas use in WWI above shows us, all of the above may be true and they are consistent with how chlorine has been used in the past. But the last one is the most important one. People are afraid of poisonous gases.
Syrians are familiar with the use of a lethal nerve agent in the controversial Ghouta attacks and Iraqis know it from Saddam’s use of chemical weapons against Kurds at Halabja and during the Iran-Iraq War. Most people have heard of chlorine and know its smell from household use. This smell, following an attack of some kind, induces fear and fear is an important force multiplier for the chlorine attacker. It makes victims breathe faster, further increasing the intake of the gas and increasing the onset of its effects. The fear and panic caused and ensuing behavior by victims increases the likelihood of injuries from conventional attacks.
Chlorine has a long history of violence. We need to be mindful of its shortcomings, however, and not turn it into something that it isnt. If we make it out to be a highly lethal bugbear, we only serve to increase its usefulness as a weapon by stoking fear. Though it is rather ineffective in and of itself, it does have properties which would make it attractive to users such as the Assad regime and terrorist groups such as ISIS. The fear that the use of chlorine gas induces into populations which, though battle-hardened against daily conventional bombings, are conditioned by their own history to fear chemical attacks is why we are seeing a revival of the use of chlorine as a chemical weapon in war.
[Photo: Flickr CC: Library and Archives Canada]