Now I come to think of it, I have seen the term "Exhaust fan" in American catalogs. Just one of many things which have only a subtle difference in wording, like the way the muffler on a car is called a silencer over here. There actually seem to be certain subjects which have the greatest difference in vocabulary - cars, food, and railroad words, for example.
The effect that somebody's dangerous work could have on innocent people who follow is probably the thing that would swing me most in favor of licensing.
Bill:
Sorry, I don't have a digital camera or a scanner for pictures, or I would have posted some already - one picture and a thousand words, etc.
Thanks for the "drum of bitter." Cheers!