I don't have this mask, but it has always looked to me like you have to take it off to breathe out, though I'm certain that Mit' knows what he's talking about. In any event, it won't do you any harm to take it off to breathe out, as long as you don't inhale any room air, and you might try using the tube and not the mask, which some people prefer. If you had flaps/gaskets on both of the holes in your previous mask, it was okay to use it as you were using it. Most of them have one gasket and a bunch of open holes on the other, and that's the problem with letting room air in. ClusterO2 Kit should be more comfortable, give you a tighter seal, and hold more O2 in the bag.