Name given to firefighters who mask up and breath air from their air packs before they are even out of the truck or close to the actual structure fire. Common to see new firefighters going "on air" before it is necessary.
Did you see him getting off the truck already on air? What a yard breather.
A "firefighter" who is either seen walking about the exterior of the fire scene, with no exposure to the toxins produced from fire, with full Self Contained Breathing Apparatus (SCBA) connected and breathing air, or, is seen exiting the fire apparatus while breathing air and has no intention of entering the burning structure. Could also be used in conjunction with "Engine Breather", see definition for Engine Breather.
That Timmy is a Yard Breather. Look at him standing next to the Chief, breathing air.