Get some discussion going on here. When do you turn on your air, as soon as you get off the truck and leave mask hanging or wait until you get into a condition you need to mask up and turn on air then and put on mask. Matter of personal preference? Do you have a SOP towards this?
One theme I've seen over and over on this thread is letting the mask hang because wearing the mask while not on air causes it to fog. As per my post, I only wear the mask (not on air) if I know for sure we are going into IDLH conditions upon arrival, thereby saving the time of donning the mask, hood, securing the helmet. However, mask fogging is definetely a big issue. On thing I've found that dramatically reduces fogging is using de-fogging spray, which you can pick up at any sporting goods store (usually used for paintball masks). It isn't full-proof, but it makes a big difference. Both on and off air.
My department uses the SCOTT 2.2 packs with integrated PASS systems. I usually turn on my bottle after being assigned for task in IDLH. If not, you stand around doing the PASS dance, like mentioned before.
Usually turn my air on when I'm on the truck, face piece hanging. Situation and or assignment dictates use.Back when I was new,went to a meth lab raid.got off the truck and the bottle that I had was empty--it was embarassing and time consuming to have to change the bottle.
As soon as I get in the jump seat I check my bottle pressure, turn my pack on, and from there it depends: if we are responding close to the station, I am in my pack and ready to be on air prior to my entry point; if the call is out in the county, I am in my pack with my face-piece on my regulator hanging. Our masks are horrible for fogging up when not flowing air. (you all could probably guess the brand). I am not one to be in the IDLH environment to don my mask, like I said I will don my face-piece just prior to my entry point. That is something I am trying to get my FF I class to get right now is air conservation, but their new and learning. I am, just to add, one of those firefighters who went through three bottles on a defensive attack, there was partial entry (if you can call it that), but I don't plan on trading my pack bottle for a little green bottle down the road.
If I know that we have a confirmed structure fire, or if I see smoke, I will fire up the bottle and let the mask hang. I know some Depts its policy to go on air as you get off the rig, but we typicaly go on air at the door prior to entry.