That's what police are supposed to do." Tear 'gas' is actually a powder Tear gas — aka agent CS (2-Chlorobenzalmalononitrile) — was invented a century ago, and has long been used as a weapon ...

Tear gas or tear smoke are or riot control agents ... The type of chemical agent used by Hong Kong police, CS gas, is actually a fine powder or crystal, and will settle in clothes, causing ongoing ...