Defend yourself against tear gas

I've participated in a few demonstrations over the years (not recently, I must confess), but never one where the authorities used tear gas on the crowd. Peaceful protest being one of our most fundamental and cherished rights as Americans, proper education in civics calls for some knowledge of practical measures one can take to defend against tear gas attack and other abuses of power. And your friends at boingboing are here to help. Remember: Only for good, never for evil!