Riot control agents (sometimes called RCAs) are
non-lethal lachrymatory agents used for riot control. Most commonly used riot control agents are
pepper spray and various kinds of tear gas. These chemicals enable to disperse a protesting or
rioting crowd, or to clear a building. They can rapidly produce sensory irritation or disabling physical effects which usually disappear within 15 minutes (for tear gas) and up to 2 hours (for pepper spray) following termination of exposure. They can also be used for
chemical warfare defense training, but their use in warfare itself is a violation of Article I.5 of the
Chemical Weapons Convention. Article II.9 of the CWC specifically authorizes their use for domestic law enforcement.
Pepper spray operator in riot gear holding a Tac700 Pepperball Launcher The active ingredient in pepper-spray is
capsaicin, which is a chemical derived from the fruit of plants in the
Capsicum genus, including
chilies. Desmethyldihydrocapsaicin, a synthetic analogue of capsaicin also known as pelargonic acid vanillylamide or PAVA, is used in another version of pepper spray known as PAVA spray and used in the
United Kingdom. Another synthetic counterpart of pepper spray,
pelargonic acid morpholide, was developed and is widely used in
Russia. Its effectiveness compared to natural pepper spray is uncertain and it reportedly has caused some injuries. When undesirables threaten an area, such as a riot after a soccer game, riot police are called in to subdue them. In these situations, the police may use pepper spray, or water cannons to neutralize the threat. Pepper spray typically comes in canisters, which are often small enough to be carried or
concealed in a pocket or purse. Pepper spray can also be bought concealed in items such as
rings. There are also
pepper spray projectiles available, which can be fired from a
paintball gun. Having been used for years against demonstrators, it is increasingly being used by police in routine interventions.
Tear gas carrying
gas masks and a
grenade launcher for deploying tear gas canistersTear gas is a non-specific term for any
chemical that is used to temporarily incapacitate through irritation of eyes and/or respiratory system. It is used as a hand-held spray or can be fired in canisters that heat up spewing out an
aerosol cloud at a steady rate. While the use of tear gas in warfare is prohibited by various international treaties that most countries have signed, use by police and for private self-defense is not banned by these treaties. Popular tear gases include the eye irritants
ortho-chlorobenzylidene-malononitrile (CS gas),
chloroacetophenone (CN gas), and
dibenz (b,f)-1,4-oxazepine (CR gas). Among a long list of substances, these three have become of greater importance than the others because of their effectiveness and low risks when used. Today, CS has largely replaced CN as the most widely used tear gas internationally.
Decontamination At room temperature, tear gases are white solids. They are stable when heated and have low
vapor pressure. Consequently, they are usually dispersed as
aerosols. All of them have low
solubility in water but can be dissolved in several
organic solvents.
Hydrolysis of CN is very slow in a water solution, especially if
alkali is added. CS is rapidly hydrolyzed in water solution (half-life at
pH 7 is about 15 min. at room temperature) and extremely rapid when alkali is added (half-life at
pH 9 is about 1 min.). CR is hydrolyzed only to a negligible extent in water solution.
CN and
CR are, thus, difficult to decompose under practical conditions, whereas
CS can easily be inactivated by means of a water solution. Skin is suitably decontaminated of CS and CN gas by thorough washing with soap and water. CS is then decomposed, whereas CN is only removed via soap and water. The effects of CR gas are greatly increased by water, causing any attempt to decontaminate CR via soap and water to increase the severity and duration of the effects. When decontamination of CR is attempted with soap and water the effects of CR can last up to 48 hours Decontamination of material after contamination with CR gas is not possible for up to 45 days. CS can be decontaminated l with a 5–10 percent soda solution or 2 percent alkaline solution. If this type of decontamination cannot be accomplished (e.g., contaminated rooms and furniture), then the only other means is by intensive air exchange—preferably with hot air. Exposed streets and sidewalks will have toxic and irritating CS powder that will be stirred into the air by traffic and pedestrians long after the cloud has dissipated, and should be washed away with water. In contrast to human beings, domesticated animals generally have lower sensitivity to tear gases. Dogs and horses can therefore be used by police for riot control even when tear gas is used.
Dispensing large quantities Backpack dispensers for riot control agents, when the intent is to use a larger quantity than possible with grenades, are one type of device used by organizations that might, for example, need to cover a prison yard. Dispensers are also made for attachment to helicopters; see
CBU-19. ==Tactics==