CS gas has been used in spray form by many police forces as a temporary incapacitant and to subdue attackers, persons, or civil protestors. Officers who are trained in the use and application of CS spray are routinely exposed to it as part of their training. It has also been used in criminal attacks in various countries.
Use of CS in war is prohibited under the terms of the Chemical Weapons Convention, signed by most countries in 1993 with all but five other states signing between 1994 and 1997. The reasoning behind the prohibition is pragmatic: use of CS by one combatant could easily trigger retaliation with much more toxic chemical weapons such as nerve agents. Only five countries have not signed the Chemical Weapons Convention and are therefore unhindered by restrictions on the use of CS gas: Angola, Egypt, North Korea, Somalia, and South Sudan.
Bahrain
CS gas was used extensively by Bahrain's police from the start of the Bahraini uprising. The Bahrain Independent Commission of Inquiry concluded that Bahrain's police used a disproportionate amount of CS gas when dispersing protests, and that in some situations, police fired CS gas into private homes in an "unnecessary and indiscriminate" manner. In one particular incident witnessed by Commission investigators, police fired "at least four tear gas canisters (each containing six projectiles) ... from a short range into the kitchen and living room of a home."
According to opposition activists and families of the dead, ten individuals died as a result of CS gas between 25 March 2011 and 17 December 2011. One allegedly died from the impact of the CS gas canister, and the remainder are said to have died from the effects of inhaling the gas. The Bahrain Independent Commission of Inquiry received information that a further three deaths may have been attributable to the use of CS gas. Of these three, one allegedly died from the impact of the canister, and two from the effects of inhaling the gas.
Canada
The Canadian Forces exposes basic training candidates to CS gas as part of gas mask training and drills. This training continues in subsequent career stages. Many law enforcement agencies also use CS gas as a riot control device. Since 2008, the SPVM police force in Montreal has increased its use of CS Gas for crowd control, although Police policy is to only use it as a last resort. Several incidents where protesters have been seriously injured by having CS gas fired at them from point-blank range have raised concerns about the methodology and training of Officers in the Montreal Riot Squad, particularly in relation to "Use of Force".
Chile
Tear gas is routinely used in Chile by Carabineros, to disrupt civilian protests. During the 2019 uprising the use of expired gas has been reported, prompting Carabineros to say that "they are like yogurt expired 5 days ago, it doesn’t damage people".
Peru
Peru Police forces spray CS gas in riot control situations.
Cyprus
CS was first tested in the field by the British army in Cyprus in 1958. At this time it was known by the code name T792.
Egypt
CS has been widely used by Egyptian Police/Military Forces from January 2011 onwards.
Hong Kong
The Police Tactical Unit of the Hong Kong Police Force used 87 rounds of CS projectiles (both riot gun launched and hand thrown) in Hong Kong on 28 September 2014 against thousands of protesters obstructing major thoroughfares in Hong Kong 2014 Hong Kong protests, also known as the Umbrella Movement.
The CS gas canisters and content used were purchased by the Hong Kong SAR Government from CHEMRING, a British weapons manufacturer. The crowd used umbrellas to fend off the gas, which was often ineffective. Apart from the HK police, CS gas spray is also used by Witness Protection and Firearms Section of Independent Commission Against Corruption (Hong Kong).
From 12 June to 4 August 2019, police used 1000 tear gas canisters. Then, on the single day of 5 August, police fired more than 800 tear gas canisters in their operations throughout almost every district of the city. In one instance, a tear gas canister was deployed indoors, in Kwai Fong station during a march, on 11 August 2019. The police initially denied the incident. In defense, protestors are seen picking up tear gas cans with thick gloves to throw them back or to extinguish them in sealed water containers.