On Monday, hundreds of protesters in Philadelphia took over Interstate 676 as part of the nationwide uprisings against police violence. In response, police officers opened fire on the crowd with rubber bullets and tear gas. The protesters attempted to escape up a steep embankment, but were trapped, forced to endure volley after volley of 2-chlorobenzalmalononitrile, commonly referred to as “CS gas,” the active ingredient in tear gas.

Philadelphia police are not alone in using tear gas indiscriminately. Countless police forces have deployed the weapon to put down the ongoing wave of protests. But while commonly used — and frequently described as “non-lethal” — tear gas’s potential effects are severe: concussions, internal bleeding, burns, even death.

Jacobin contributor Arvind Dilawar spoke with Anna Feignbaum, author of Tear Gas: From the Battlefields of World War I to the Streets of Today, about the use of this “non-lethal” weapon in the United States, the international regulations on its manufacturing and deployment, and how protesters can defend themselves from its effects.