Experiencing tear gas doesn't come without long term effects on health. There are also many varieties available, but CS is pretty rough and the most common form used in the US.
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.)
I'm not saying there isn't something worth protesting right now, but the timing is far from ideal.