I am no expert but this feels like a fun and useful bookmark:

https://phr.org/our-work/resources/preparing-for-protecting-against-and-treating-tear-gas-and-other-chemical-irritant-exposure-a-protesters-guide/

Something I learned / remembered from reading that:

Though tear gas was classified as a chemical weapon in 1993
and banned from use in international warfare, law enforcement
officers are still allowed to use it on civilians in the United States.

That’s fun.