Tear gas

First you feel a slight irritation in your eyes. Then it creeps to the back of your throat. Quickly, the irritation morphs into a sting and then an all-out burn. You reflexively gasp for air, even though it’ll just make the burning worse. The panic and distress intensifies. If you’re lucky, you’ll manage to stagger away from the gas, and wash out your eyes with water or saline.

For decades, police forces have used tear gas as a riot-control agent, deploying it to disperse crowds or to stop fighting. It’s euphemistically referred to as “less lethal” force by law enforcement, but this is misleading. Tear gas has certainly killed people, whether by asphyxiation from a deadly concentration of the chemical, or by the blunt trauma of a canister itself.

Though tear gas is banned from battlefields, the chemical is deployed domestically worldwide to quell protests and civil unrest. You might be breathing some before long.

Let’s take cover, then dive in.

2,300: The number of tear gas canisters that the Hong Kong police fired onto a university campus in a single day during a siege in November 2019.

$9.50: The starting hourly wage for factory workers producing tear gas for Nonlethal Technologies, a Pennsylvania-based company and a major exporter of the chemical.

590°F ( 310°C): The boiling point of 2-chlorobenzalmalononitrile, the primary component of tear gas.

45%: Amount a typical tear gas canister contains of the chemical 2-chlorobenzalmalononitrile, or CS.

$12 billion: The estimated global revenue from the non-lethal weapons industry by 2023, almost double that of 2016.

The first thing to know about tear gas is that it’s not typically a gas in normal situations. What we call tear gas is generally a reference to a chemical substance called 2-chlorobenzalmalononitrile—CS for short.

To deploy CS, which is typically a solid, police can fire a tear gas cartridge from a grenade-launcher gun. Each cartridge has several separate submunitions, each containing CS smoke agent. In the submunitions are also fillers, consisting of different ingredients that each play different roles. Potassium chlorate is an oxidizer, for example, while sugars like sucrose or lactose serve as fuels, and substances like magnesium carbonate and sodium bicarbonate slow the rate of combustion. On firing, the filler burns, and this creates smoke that then disperses widely.

Tear gas should also never be fired directly at people, but instances abound of protesters being directly hit by canisters—sometimes to lethal effect. In dense urban areas like Hong Kong, narrow streets and tall buildings can create a funnel effect, potentially making any tear gas deployment even more potent. The gas can also seep into buildings through central air-conditioning units, circulating for long periods of time.

The immediate effects of tear gas, while unpleasant, wear off fairly quickly. Much less is known about long-term health effects of exposure, although some health experts are concerned that the coughing caused by inhalation of the gas just spreads coronavirus that much more quickly within crowds. Great.

Strict police and manufacturer guidelines are supposed to govern the use of tear gas. For example, it should only be used in open or well-ventilated areas with clear exit routes. The Hong Kong police’s violation of these guidelines has been well-documented on multiple occasions.

The use of tear gas to quell protests has been hotly debated in recent years, and that debate has become just part of the increasingly strident arguments to reform policing in the US. There, protests against the death of an unarmed black man named George Floyd, who asphyxiated in police custody after spending counterfeit money in Minneapolis, Minnesota, attempted to put a spotlight on violent policing methods used against people of color.

The short-term result: More violent policing methods against people of color and those who protested to support them. Videos of the deployment of tear gas against what appeared to be peaceful protesters spread like a cloud of smoke agent. Following enormous backlash against tear gas and other violent methods, some US municipalities have even disbanded their police force—or the force resigned en masse after specific officers were suspended for shoving a 75-year-old protester.

“It may have been the gas, as much as anything, that brought West Belfast together in virulent opposition… One correspondent who reported on the siege described the gas as a kind of binding agent, a substance that could ‘weld a crowd together in common sympathy and common hatred for the men who gassed them.’”

— Say Nothing: A True Story of Murder and Memory in Northern Ireland, by Patrick Radden Keefe

1914: The French deploy tear gas grenades during World War I, the first major use of the weapon.

1919: In the US, general Amos Fries, head of the Army’s Chemical Warfare Service, launch a PR campaign to promote “war gases for peacetime use.”

1925: The Geneva Protocol prohibits the use of chemical and biological weapons, including tear gas, on the battlefield.

1928: Two US scientists discover CS, the chemical compound that we now widely call tear gas.

1960s: Tear gas is used widely on anti-war and civil rights activists in the US. The French also deploy it against student and worker uprisings in 1968.

1969: The Royal Ulster Constabulary uses tear gas for the first time in Derry, Northern Ireland, at what is known as the Battle of the Bogside.

1993: The Chemical Weapons Convention, signed by almost every country in the world, again confirms the ban using tear gas in wars—but not for domestic law enforcement.

2013: Turkish police reportedly fire 130,000 tear gas canisters over three weeks during the Gezi protests.

2019: The Hong Kong police deploy a record 16,000 tear gas canisters against anti-government protesters between June and November.

2020: Tear gas is used to clear peaceful protesters outside the White House so US president Donald Trump can walk to a nearby church.

A gelato shop in Hong Kong has developed tear gas flavored ice cream. In developing the recipe, the owners experimented with wasabi and mustard, but ultimately settled on roasted and ground black peppercorns to create a slightly irritating aftertaste. The flavor has been a hit.

Hong Kong protesters have become real experts at dealing with tear gas. They line tram tracks with water bottles, so that protesters have easy access to liquid to douse canisters with. They use tennis rackets and hockey sticks to lob canisters back at the police. They extinguish burning canisters with metal dinner plates, and trap them in thermoses with water and mud. It’s all a carefully choreographed team effort, honed through months of protests, as this video by photojournalist Alex Hofford shows.

At the same time that China has been cracking down on dissent in Hong Kong, some members of the Chinese diplomatic corps recently have been taking a more aggressive approach to international relations. It’s been dubbed “Wolf Warrior” diplomacy in reference to a 2015 movie that is a sort of Chinese version of Rambo.

Perhaps the best way to understand that reference is to read this plot summary for 2017’s Wolf Warrior II in the Hollywood Reporter:

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Read more about how this diplomacy is undergirding China’s changing influence in this week’s member-exclusive field guide.