Warfare During World War I, various forms of<unk>  were used in combat and<unk>  was the most common form of chemical weapon used. None of the belligerents believed that the use of irritant<unk> es violated the Hague Convention of 1899 which prohibited the use of "poison or poisoned weapons" in warfare. Use of chemical weapons escalated during the war to lethal<unk> es, after 1914 (during which only<unk>  was used). The US Chemical Warfare Service developed<unk>  grenades for use in riot control in 1919. Use of<unk>  in warfare, as with all other chemical weapons, was prohibited by the Geneva Protocol of 1925: it prohibited the use of "asphyxiating<unk> , or any other kind of<unk> , liquids, substances or similar materials", a treaty that most states have signed. Police and civilian self-defense use is not banned in the same manner.<unk>  was used in combat by Italy in the Second Italo-Ethiopian War, by Japan in the Second Sino-Japanese War, by Spain in the Rif War and by the United States in the Vietnam War,and Israel-Palestine conflict.<unk>  exposure is an element of military training programs, typically as a means of improving trainees' tolerance to<unk>  and encouraging confidence in the ability of their issued protective equipment to prevent chemical weapons exposure. Riot control Certain lachrymatory agents, most notably<unk> , are often used by police to force compliance. In some countries (e.g., Finland, Australia, and United States), another common substance is mace. The self-defense weapon form of mace is based on pepper spray which comes in small spray cans. Versions including CS are manufactured for police use. Xylyl bromide, CN and CS are the oldest of these agents. CS is the most widely used. CN has the most recorded toxicity. Typical manufacturer warnings on<unk>  cartridges state "Danger: Do not fire directly at person(s). Severe injury or death may result."<unk>  guns do not have a manual setting to adjust the range of fire. The only way to adjust the projectile's range is to aim towards the ground at the correct angle. Incorrect aim will send the capsules away from the targets, causing risk for non-targets instead. Counter-measures A variety of protective equipment may be used, including<unk>  masks and respirators. In riot control situations, protesters sometimes use equipment (aside from simple rags or clothing over the mouth) such as swimming goggles and adapted water bottles. Activists in United States, the Czech Republic, Venezuela and Turkey have reported using antacid solutions such as Maalox diluted with water to repel effects of<unk>  attacks, with Venezuelan chemist Mónica Kräuter recommending the usage of diluted antacids as well as baking soda. There have also been reports of these antacids being helpful for<unk> , and for capsaicin-induced skin pain. During the 2019 Hong Kong protests, frontline protesters became adept at extinguishing<unk> : they formed special teams that spring into action as soon as it is fired. These individuals generally wear protective clothing, including heat-proof gloves, or cover their arms and legs with cling film to prevent the painful skin irritation. Canisters are sometimes picked up and lobbed back at police or extinguished straight away with water, or neutralized using objects such as traffic cones. They share information about models of 3M respirator filters which have been found to be most effective against<unk> , and where those models could be purchased. Other volunteers carry saline solutions to rinse the eyes of those affected. Similarly, Chilean protesters of Primera Línea have specialized individuals collecting and extinguishing the<unk>  grenades. Others act as<unk>  medics, while yet another group, the so-called shield-bearers, protect the protesters from the direct physical impact of the grenades.
Tear gas
Mustard gas
Bottled gas
Air bronchogram
Mydicar
Pustular bacterid
Wheeze
Transudate