Violent protests have ravaged Ferguson, Missouri since Aug. 9, after a police officer shot and killed an unarmed 18-year-old who is believed to have robbed a convenience store. The Ferguson Police Department has been criticized for its crowd control tactics that have included plumes of tear gas, sprays of rubber bullets and loud blasts from sound cannons.
Last week, the Ferguson Police Department released the incident report from the shooting. Police Chief Thomas Jackson identified the officer who shot Brown as Darren Wilson, who has been a member of the police force for six years, the New York Times reported. The release of the incident report has rekindled anger among Ferguson residents, and some see the action as an attempt to justify the shooting of Brown, prompting worries that protests could take another violent turn.
If that happens, police will likely continue using tactics to keep protestors under control, but how do these crowd control technologies work and how dangerous are they? [10 Historically Significant Political Protests]
Tear gas is a nonlethal chemical weapon. It comes in different forms, and pepper spray is even considered a type of tear gas. But the most widely known type, and the kind police are using in Ferguson, is CS gas. This variety of tear gas targets the eyes and causes searing pain, tearing and in some cases even temporary blindness, said Hamish de Bretton-Gordon, a chemical weapons specialist and chief operating officer of SecureBio, a chemical, biological, radiological and nuclear security firm in the United Kingdom.
Tear gas also acts as an asphyxiant, meaning it makes it difficult to take in oxygen. When humans breathe in the gas, it mixes with liquid in the lungs. This can cause coughing and difficulty breathing, and those who have been exposed become disoriented and dizzy, and often vomit if they swallow the chemical. [5 Lethal Chemical War Agents]
"It's so unpleasant that it renders you incapable of doing anything productive, which is exactly the goal of crowd control," de Bretton-Gordon told Live Science.
The Chemical Weapons Convention in 1993 made it illegal for signatory countries to use tear gas in warfare. However, it's perfectly legal to use the weapon for civil crowd control against a country's own citizens.
"It's a strange sort of law there,"de Bretton-Gordon said.
Police have used tear gas in the United States during major civil protests, including the Occupy Wall Street movement and now in Ferguson.
The effects of tear gas usually don't last more than 30 minutes. If people exposed to tear gas can get to an open area with fresh air, then they typically recover quickly, de Bretton-Gordon said. But using tear gas to control crowds poses a danger, because it acts as a chemical toxin and some people react much more severely than others. The damaging effects also depend on how much tear gas people are exposed to. In some cases, the gas can kill people, especially those who have serious pre-existing medical conditions, de Bretton-Gordon said.
Even the explosion of tear gas is dangerous if it's not deployed properly. The blast alone can seriously injure people, de Bretton-Gordon said.