Law enforcement agencies use a number of devices and projectiles to help disperse crowds. Previously labeled as “nonlethal,” these devices are now being dubbed as “less lethal” because sometimes they can be deadly.

On June 5, Mayor Jenny Durkan and police Chief Carmen Best announced a 30-day ban on tear gas in response to demonstrations in Seattle over the killing of George Floyd. Seattle officers had repeatedly used pepper spray, tear gas, flash-bang grenades and foam-tipped projectiles to disperse crowds.

Later on June 15, an ordinance passed by the City Council said any Seattle agency may not own, purchase, rent, store or use “kinetic impact projectiles, chemical irritants, acoustic weapons, directed energy weapons, water cannons, disorientation devices, ultrasonic cannons or any other device” used similarly.

Less-lethal devices

TEAR GAS is commonly not a gas but a micro-pulverized powder of 2-Chlorobenzylidenemalononitrile (CS) or 2-Chloroacetophenone (CN). When dispersed, solid pellets become aerosolized and the substance attaches to mucous membranes and moist skin. This results in intense tearing of the eyes and burning irritation on skin and in the nose, mouth and throat. It can also cause disorientation. It is often deployed through thrown or launched canisters and grenades. Tear gas was first used in World War I.

Possible harm: At low concentrations in an open environment, CS and CN gasses can be nonlethal. But large doses released in confined spaces or in close proximity can severely damage respiratory and digestive tissues, increase heart rate and blood pressure and cause cardiac problems. Canisters could cause blunt-trauma injuries if they are not properly fired over crowds.


PEPPER SPRAY uses the active ingredient oleoresin capsicum (OC), made from the compound capsaicin, which gives chili peppers their heat. When it comes in contact with mucous membranes in the eyes, nose or throat, it triggers an instantaneous inflammatory response with intense pain that can incapacitate a person for up to several minutes.
Air guns are pistols and rifles powered by carbon dioxide or nitrogen gas from a cartridge or an external tank to launch gelatin balls filled with pepper-spray balls.


Possible harm: A direct shot at a person’s head or face can break the skin, break a nose or cause permanent blindness if hit in an eye. It can cause the same respiratory and cardiovascular problems as tear gas.


FLASH-BANG GRENADES, or stun grenades, are small canisters filled with pyrotechnic chemicals that release a bright flash and loud bang when thrown or fired. Developed in the 1960s by the British Special Air Service as training devices, they were later used in the 1970s to help rescue hostages.

Model 7290 releases light and sound through slits in the top and bottom. Some models can also release tear gas.
● Light intensity: 4-5 million candela*
● Sound level: 165-175 decibels**

M84 releases light and sound through side holes.
● Light intensity: 6–8 million candela*
● Sound level: 170–180 decibels**

Sting ball releases light, sound and more than 100 rubber balls in 360 degrees, up to 50 feet from the point of detonation.
● Light intensity: 6 million candela*
● Sound level: 170-180 decibels**

*One candela is the intensity of light created by a single candle.
**Decibel level within 5-foot radius of device detention. A balloon popping is about 125 decibels.


Possible harm: Flash-bang grenades detonate with enough force to turn gravel, small stones and other debris into shrapnel. Most flash-bangs when detonated are over 165 decibels. Exposure to 120 decibels (sound of a jet taking off) longer than 30 seconds is considered dangerous. If detonated too close to a person, the chemical flash can cause burns and the rubber balls can break skin.


Less-lethal projectiles

These kinetic impact projectiles come in a variety of sizes and materials. They are designed to transfer kinetic energy (inflict pain) rather than piercing through the skin.

are made of rubber, foam, plastic or wood. They were first used by the British Army in Northern Ireland during the early 1970s. In 1989, Israeli security forces started using two types of rubber bullets — a rubber-coated steel sphere (rubber ball) and a rubber-coated metal cylinder (baton). In 1992, after the Los Angeles riots, the LAPD adopted the use of rubber bullets. During
the 1999 WTO riots, Seattle law enforcement also used rubber bullets to disperse protesters.

Possible harm: Injuries vary from bruises to broken ribs to blindness. In 2017 the British Medical Journal found that out of all the people who were injured by rubber bullets, 15% were left with permanent disabilities, 3% died, and of those who survived, 71% had severe injuries.


OTHER KINETIC IMPACT PROJECTILES come in multiple sizes and internal materials and fit different devices. At long distances they are less accurate than ordinary bullets.

40mm projectiles have plastic bodies with crushable-foam noses that can be loaded with a variety of powders. Other projectiles have gel noses or release multiple smaller projectiles or rubber balls.
When fired from a launcher the average velocity is 295 feet per second (fps) with a range of up to 120 feet. This type of projectile was developed by the U.S. military in 1995.


37mm projectiles are also fired from a launcher. Projectile velocities vary by internal material, with bean-bag rounds at 220 fps, multiple foam batons at 320 fps and rubber ball-filled cartridges at 300 fps.

12-gauge projectiles do not require a special launcher and can be fired from a standard shotgun, unlike the 40mm and 37mm projectiles. This size of projectile can contain bean bags, single or multiple batons and rubber balls.

Possible harm: Because less-lethal projectiles transfer kinetic energy directly to the impact site, the force can break and fracture bones, explode eyeballs and damage internal organs. If fired at close range, they can even break the skin. A direct hit to the chest could result in heart arrhythmia, or broken ribs that can puncture the lungs or heart. Direct hits to the face can break the nose or cause permanent blindness.


Historical control of tear gas in warfare and riot control

While numerous international agreements bar the use of tear gas in war, there are no restrictions on its use for domestic crowd control.


1899: The Hague Convention on land warfare was ratified by 51 countries (but did not include the U.S.) which agreed to “abstain from the use of projectiles, the sole object of which is the diffusion of asphyxiating or deleterious gasses.”

1907: Second International Peace Conference included the U.S. and banned the use of all “poisons or poisonous weapons.” This was ignored during World War I.

1925: In response to the death and suffering caused by the large-scale use of chemical warfare during World War I, the League of Nations signed the Geneva Protocol banning the use of asphyxiating, poisonous or other gasses or any biological weapons.

1975: U.S. President Gerald Ford signed and ratified the Geneva Protocol, renouncing the use of lethal and incapacitating chemical and biological weapons in war, but excluded riot-control agents and chemical herbicides as part of the ban.

1993: The U.S. signed the Chemical Weapons Convention and agreed “to chemically disarm by destroying any stockpiles of chemical weapons they may hold and any facilities which produced them, as well as any chemical weapons they have abandoned on the territory of other countries in the past.”
The Chemical Weapons Convention does not prohibit use of chemical agents for:

  • Industrial, agricultural, research, medical, pharmaceutical or other peaceful purposes
  • Protective purposes, namely those purposes directly related to protection against toxic chemicals and to protection against chemical weapons
  • Military purposes not connected with the use of chemical weapons and not dependent on the use of the toxic properties of chemicals as a method of warfare
  • Law enforcement including domestic riot control purposes