A few years ago this would've come as a joke because air has always been free (not always) so why pay now? But with pollution being transparent (not always, of course) and you don't even notice it you're breathing it until, for example, you clean your nose and notice all the black dirt that comes out of it due to the pollution. This video below was filmed in Georgia (located in Eastern-Europe, not the American state ) where they made a fake tax that people had to pay and those hit with it though that it was real. Would I pay for air if it'd get even worse? Probably not but maybe in an emergency, I would.