If police will attack you with acid or something like that (I heard these anti-riot trucks can do it), you possibly can protect yourself by spreading yourself with greasy cream. You also can add some soda to the cream to claim better protection against some kind of acid. P.S. Oh wish a knew that a week ago...
That is also the absolute worst thing to do if they lob tear gas at you. The tear gas irritant will absorb into the greasy cream and hold tight next to your skin. In any case, there are no reports that the police are using those water guns with acid. That would be both very expensive, and the damage that could cause would be the type that the Iranian government couldn't hide. That would enrage the Iranian populace like nothing else.
