not a good idea at all. Even if the air is fresh, the BC may not be. You could be saving your life in one situation, but killing yourself in another. You can get all sorts of fungus and bacterial growth in your BC. Then you breath it in and infect your lungs. Just not a good idea. Even if the stuff doesnt thrive inside the bladder, many diff types of "bugs" can go dormant and then boom. your lungs have plenty of 02 and moisture. I dont recomend that practice......but in an attempt to save my own life.......who knows, I just might do it............