I see.
Who would've thought a fire extinguisher could be so effective. 
Years ago, when I was a teenager, me and a bunch of buddies got sprayed down with one of those dry fire extinguishers. It was horrible, it's like breathing in a cloud of dust you can't stop, and then the residue leaves you scratching like you've got poison ivy.
Everyone was fine after 10 - 20 minutes, but it was gross.
Fella that did it felt terrible, thought all fire extinguishers were plain water.