Seriously though, I must go with Brian G. on this one folks. "Regional" Reason??? I don't need a blanket answer for looking both ways when I cross a street. Busy street, I pay more attention. Just like we should pay attention to where we live and work as far as attic ventalation and venting into them. Causing visible suspect mold in an attic crawl space?!? Don't vent there anymore. Dry climate?!? don't worry about it. It is all realative folks. Thanks for your time.