Hate to tell you, but teargas ain't all that safe. When we went through training, those of us who had lenses to correct our vision were told to wear our glasses on those days, because if you wore contacts, it would mess up your eyes something fierce.
As far as not doing any harm? Those kids have little lungs, and aren't able to handle it as well as the adults, and there could be permanent damage.,
So what would you have them do instead?
Stand there like bitches and let them pass.