What Does Tear Gas Even Do To You?

The governor of Maryland announced a state of emergency Monday as police officers in Baltimore clashed with protesters after the funeral of Freddie Gray, 25, who died in police custody. Officers dressed in helmets and riot gear used tear gas on the crowd in an attempt to disperse them, according to The New York Times.

We've seen tear gas used by police in several recent incidents, including the protests in Ferguson after the death of Michael Brown, and at Ohio State when rowdy students celebrating the football team's win got out of hand. But the use of tear gas in war is banned under the terms of an international agreement called the Chemical Weapons Convention, which has been in effect since 1993. Yet, local police departments in the U.S. and other countries are allowed to use tear gas for "domestic riot control," The Washington Post explained during its Ferguson coverage. Sven-Eric Jordt, a chemical weapons expert at Duke (formerly Yale) told National Geographic that this apparently contradictory rule was "illogical."

Tear gas under the Geneva Convention is characterized as a chemical warfare agent, and so it is precluded for use in warfare, but it is used very frequently against civilians.
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According to The National Journal, the most commonly used tear gas contains a chemical called 2-chlorobenzalmalononitrile. It causes severe pain, watering eyes, and makes it hard to breathe. Jordt said in an interview with Vox last year that the effects of tear gas are similar to the chemical reaction that causes us to tear up when chopping onions, but about 1,000 times more potent.

Jordt, who told Vox he was tear-gassed himself during protests in Germany in the 1980s, described the feeling. It sounds horrible.

It's extremely painful. Your face starts burning very quickly and your eyes start tearing. The eyelids shut and you can't do much. ... You get severe pain in your nose and throat and you also get a lot of mucus and snot production, and that obstructs your breathing.
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There aren't any studies that look at the long-term effects of tear gas on humans, according to The National Journal, but the immediate effects are temporary, lasting a few hours. The usual treatment for victims of tear gas exposure it to first rinse the eyes with water or, weird as it might sound, to pour milk in the eyes.

So even though we've become accustomed to seeing tear gas used in clashes between police and protestors or rioters, Jordt told Vox he's concerned that people think it's safe to use. If we're banning its use in war, it's troubling that we feel comfortable using it on our citizens.

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