The San Francisco Sheriff’s Department conducted a tear gas training exercise at the San Bruno jail at 12:45PM on a windy day exposing the nearby elementary school to both CS (2-chlorobenzalmalononitrile) and OC (oleoresin capsicum) tear gas.
“Interim principal, John Nazar, said he walked the perimeter of the school to try and figure out what it was.
He said he didn't learn until later that it was tear gas and pepper spray.
“‘It was very strange,’ he said, adding that he didn't know whether to keep the children outside or inside. ‘It was challenging.’”
CS is a synthetic molecule that is solid at room temperature. It and similar compounds activate a pain and heat receptor in the body. CS boils at 310 °C so it requires a flammable propellant and an ignition system. CS breaks down into various other compounds at high temperatures with an unclear toxicology. It breaks down with pH 9 alkaline water which is commercially sold or produced by mixing some baking soda into water.
OC is an oily extract from hot pepper plants. Weapons makers emulsify it in water and propylene glycol or dissolve it in organic solvents to make aerosol pepper spray. Sriracha, a popular type of hot sauce, lands between 1,000 and 2,500 on the Scoville scale, a measure of spiciness. OC pepper sprays, by contrast, clock in north of 2,000,000 on the same scale. Unlike CS, it does not actually breakdown with water though it can soothe the burning sensation. (Some protestors use milk or milk of magnesia to mitigate OC tear gas but the efficacy is debatable).