The Devil Wears Prada actress' casual use of the word “gassing” is, of course, a huge problem, and trivializes genuine war crimes throughout history. “Gassing" brings to mind the Holocaust, and the use of fatal gases during World War I.
Whereas, obviously, the “gas” used by the U.S. law enforcement agencies to disperse riots and so forth is NOT that kind of gas (which has been illegal under international law for a long time.)
Pepper spray is derived from, surprise, chili peppers, and, it goes without saying, isn’t fatal. The recommended treatment for getting chili-derived tear gas in your eyes is to "blow dry air directly onto the eye."
But more importantly: