Tear Gas: What you need to know- By Prof.Kirthi Tennakone

Tear Gas: What you need to know- By Prof.Kirthi Tennakone

Tear Gas: What you need to know- By Prof.Kirthi Tennakone

A file photo of the police firing tear gas during a recent protest

National Institute of Fundamental Studies


We hear incidents of tear gas deployment somewhere almost every day and too frequently in Sri Lanka these days. The Police direct tear gas shells to crowds they determine as unruly. The tactic serves the purpose of avoiding the bullet, or other lethal methods of combat, to deter an emotionally agitated mob about to engage in a criminal offence. However, indiscriminate use of tear gas poses health risks hard to ignore.

The United Nations Human Rights Commission has classified tear gas as a less – lethal weapon, and said that even less-lethal weapons must be employed only when they are subject to strict requirement of necessity and proportionality, in situations in which other less harmful measures have proven to be clearly ineffective to address the threat.

Amnesty International states: Tear gas may only be used in situations of more generalized violence for the purpose of dispersing a crowd, and only when all the other means have failed to contain the violence. It may only be used when people have opportunity to disperse and not when they are in a confined space or where roads or other routes of escape are blocked. People must be warned that these means will be used, and they must be allowed to disperse. Cartridges with chemical irritants may never be fired directly at any person. If used, repeated or prolonged exposure should be avoided and decontamination procedures should be followed immediately.

What is tear gas?

At the time of World War I, parties in conflict conducted intense research to develop new chemical weapons to evade restrictions imposed by The Hague Convention of 1899, forbidding deployment of projectiles containing poisonous gases – arguing non-lethal repellents do not fall into the category of poisons.

The Nobel laureate British Chemist William Ramsay suggested that relatively innocuous substances, similar to the ingredient named acrolein present in smoke, bringing tears to eyes (known as lachrymators), would ideally serve the purpose. In 1914, France used a synthetic lachrymator for the first time to expel German troops stationed in trenches. Subsequently, the Geneva Protocol of 1925 restricted use of chemical and biological agents in war, and finally, the United Nations, Chemical Weapons Treaty of 1993 banned tear gas in warfare. However, use of tear gas as a riot control agent in domestic situations was not restricted.

The tear gas compound widely used today is chlorobenzal malononitrile, conventionally referred to as CS gas – an abbreviation derived from the first letter of the surnames of two American chemists, Ben Carson and Roger Stoughton, who synthesized the compound first. Calling it a gas is a misnomer, because CS is actually a white solid material. On the firing of a tear gas shell, fine particles of CS disperse in the atmosphere as smog. The shell consists of a canister filled with a solution of CS in a volatile liquid. The heat of the burning gun powder, vaporizes the solvent, releasing smog from the propelling shell. In an alternative method, a pyrotechnic mixture is burnt to disperse CS as smoke

The minute aerosol particles of CS irritate the mucous membrane of eyes, mouth and respiratory track inducing a burning sensation. The effect is transient and relieved after a while, unless the victim is oversensitive or the exposure has been heavy.

Health Hazards of Tear Gas

Tear gas is ‘officially’ considered to be safe and only induces short-term effects, such as tearing from eyes, cough and throat irritation, sneezing, chest tightness and shortness of breath. These symptoms develop within few seconds of exposure and disappear in tens of minutes, provided the affected individual moves to uncontaminated atmosphere. Nevertheless, statistically significant adverse events have been reported – respiratory failure and death, severe allergies and eye injuries leading to blindness. Prolonged exposure and high doses increase the probability of such happenings. Dangers are greatest when tear gas is released into enclosed spaces or when the smog enters buildings.

The American Lung Association warns tear gas can cause chemical burns, allergic reactions and respiratory distress. People with pre-existing respiratory conditions such as asthma and chronic obstructive pulmonary disease, have higher risk of developing severe symptoms.

Thelong-term effects of tear gas exposure have not been evaluated sufficiently. Here, details are scanty and based on deplorably cruel experiments where monkeys are subjected to tear gas inhalation. In one such experiment, monkeys confined to an enclosed space have been exposed to a heavy dose of tear gas. Animals developed lung lesions and pneumonia and many died within few weeks. Recent investigations reveal that even at normal levels of exposure, clinically noticeable respiratory complications, sometimes continue for several weeks.

Concerns have been raised that tear gas may be mutagenic and clastogenic – meaning it can disturb and alter DNA, inducing cancer. The issue remains controversial as laboratory tests have yielded positive as well as negative results. The molecule of the lachrymator chlorobenzal malononitrile contains a covalently linked chlorine atom and classified as an organic- chlorine compound. Substances of this category and their degradation products are generally poisonous and sometimes carcinogenic.

The tear gas industry is a flourishing business; because of the heavy demand, unregulated products could enter the market. The extreme toxicity of unknown chemicals present as impurities is not ruled out. International law requires that non-lethal weapons and materials be tested independently of the manufacture’s specifications. In reality, testing of tear gas products would not be easy.

Tear gas and COVID

Exposure to tear gas could increase the rate of transmission of COVID-19 from those infected and also enhance the susceptibility to the illness when exposed to the virus. Coughing and sneezing after exhalation of tear gas releases more of the pathogen from those carrying it. The virus establishes easily when the mucus membrane gets irritated by the tear gas smog. Yet, crowds protesting against compulsory COVID control measures have been tear gassed. In 2020, the American Thoracic Society called for a moratorium on use tear gas and other chemical weapons.

Banning tear gas?

Human rights activists and legislators worldwide have voiced their opposition to indiscriminate use of tear gas. Some have demanded a complete ban, while other argue for restricted use. The general consensus is that tear gas should not be directed at peaceful demonstrators, because every man or woman has right to protest.

The world seems to be yet unready to impose a total ban of tear gas. It is an effective, less-lethal way of curbing emergence of riot behavior in a crowed. If tear gas is unavailable, law enforcement personnel would circumstantially resort to standard lethal methods of intervention. Tear gas cannot distinguish between wrong doers and peaceful persons or between leaders and participants; but gun, which can, would be far more dangerous. Tear gassing sometimes provokes violence, but rarely allow pinpointed individual vindictive action. What is needed at this juncture is; legislation to regulate tear gas use and educating law enforcement personnel.

Author can be reached via Email: ktenna@yahoo.co.uk

Comments are closed.