So, seems to be a lot of mis-conceptions here.
The powder is cornstarch with food coloring. Unless you have a food coloring allergy, respiratory issues or are allergic to corn there isn't much to worry about. I have shot 3-4 of these for my local paper and two for the company that runs them and feel just fine afterwards. A painters mask reduces the amount you inhale by quite a large margin. If you want to filter it all out you will need a good respirator.
It's cornstarch, it dissolves quickly. It'd be a different thing if it was silicone based powder as that would sit in the lungs forever.
I wouldn't go leaping to conclusions that just because it's corn, it's safe...