As Ferguson, MO experiences an escalation of militarized force, much of the focus has been on the assault and sniper rifles, tanks and other military-grade weaponry used by police. One dangerous aspect has escaped as much attention: tear gas.
In an effort to disperse protestors, Ferguson police have lobbed canister after canister of tear gas into the crowd. Wesley Lowery, a Washington Post journalist, had this early account of those fleeing chemical assault:
Others fled, crying out for water as stinging tear gas bit at their eyes.
“I had to go back for my sister,” explained 18-year-old Travis Hollins, who ripped off his shirt as tears streamed from his eyes. His 21-year-old sister had fallen near a tear gas canister, he explained, so he had run back into the fray to help her.
Tear gas is a chemical weapon that has been banned during warfare since the Chemical Weapons Convention of 1993, according to The Washington Post. But international accords do not apply to domestic affairs and tear gas can be used as a tool of riot control. It is certainly not new and has been used in recent years to subdue crowds, notably as part of the Occupy demonstrations of 2011, including an infamous incident in which pepper spray -- a related substance -- was used against handcuffed protestors at the University of California, Davis.
Internationally, tear gas is commonly used. Last night on Twitter, for example, residents of Gaza were offering advice to Ferguson's protestors on how to withstand and protect against injury from the stuff.
"I'm very concerned about the increased use, and the much laxer attitude we've developed towards the potential health effects," Sven-Eric Jordt, a scientist at Duke University who researches tear gas, told Vox.
There are a few different types of tear gas, especially if you include in the taxonomy related compounds, like mace and pepper spray, though the two most commonly used for crowd dispersal are referred to as CS and OC, for oleoresin capsicum.
OC, just like pepper spray, is made of chili pepper oil at a concentration so profoundly strong it scores up to 5.3 million Scoville units, as Deborah Blum explains on her PLOS Blog, Speakeasy Science. What's more, OC isn't just the capsicum oil.
According to research Blum found, conducted by scientists at Duke and the University of North Carolina, OC spray also often includes a liquid solvent and a propellant. Options for propellants on the toxic menu include nitrogen, carbon dioxide and halogenated hydrocarbons (like the absolutely icky Freon). "Inhalation of high doses of some of these chemicals can produce adverse cardiac, respiratory, and neurologic effects, including arrhythmias and sudden death," wrote the researchers.
The tear gas known as CS has a chemical base called 2-chlorobenzalmalononitrile. It differs from OC in its 30- to 60-second delay in setting in, according to Gizmodo. Unlike the capsicum, CS reacts when wetted by the delicate areas of a person's face -- eyes, mouth, respiratory tract, sweating skin -- and can amplify the effects of the chemical.
Jordt told Vox:
The way these gases work, and this is what we do research on, is that they activate pain receptors -- the pain sensing nerves in our body. The cornea is densely covered with these receptors. When tear gas activates these pain receptors, that leads to body reflexes like profuse tear secretion and a muscle cramp in the eyelid that causes them to close. These are all protective responses that the body has to pain, and with the gas they become extremely exaggerated.
There are situations where this can be very dangerous or lethal. If somebody has asthma, for example, or a hypersensitivity or an airwave disease that can be very dangerous.
It should be noted here that the St. Louis metro area has an adult asthma rate of just over 10 percent and a childhood asthma rate of 14 percent -- the highest in the state and above the national average.
Many protestors recommend using milk or Coke to counteract the burning sensation of tear gas, possibly because these contain neutralizing acids, according to Slate. A paper published in the BMJ revealed that in extreme cases, those suffering the ill effects of tear gas may require chemical decontamination at a hospital or even ventilation support for those with respiratory complications.
In 2012, the organization Physicians for Human Rights called for a policy group to address the use of tear gas, which is classified as non-lethal, because of some health concerns.
“It is increasingly evident that tear gas has effects far more severe than commonly understood,” said the organization's deputy director Richard Sollom at the time. “The tears it produces are not limited to those caused by temporary stinging of the eyes, but flow also from people who receive long-lasting injuries and trauma from its indiscriminate use, and from friends and relatives of tear gas victims left blind, wounded, or dead. The world must consider whether it is appropriate to use such toxic chemical agents at all against unarmed civilian populations.”