https://www.washingtonpost.com/news/morning-mix/wp/2014/08/1...
(Of course we can discuss if most of the uses of tear gas are wrong, but lets for a moment think that we have a moment were we need to chase away a crowd of evil persons riotong and threatening to kill perfectly innocent children.)
But, we have de-escalation tactics, riot shields, smoke canisters, and literally guns.
If an officer wouldn't fire a gun, I think he shouldn't use tear gas.
I'd rather take that again than a good number of other unpleasant experiences.
Mentioned it in the same sentence as the use of actual guns seems to indicate that you either talk about a different kind of tear gas or that you don't know what you are talking about at all.
We were a few hundred recruits who were exposed to it at that week and everyone seemed to be fine next day.
I'm fourty now and I've never experienced any problem that I would guess comes from my experience with tear gas.
(FWIW, I was exposed to it in a closed room but only briefly, not more than a minute or so I'd guess, possibly less.)