and where else would it come from?The assumption is the black stuff on the mask came from breathing in???
what INSIDE YOUR LUNGS generates that kind of gunk? the only way anything like that would be coming OUT of your lungs would be if you had already inhaled it. The mucus inside your respiratory system traps a great deal of the junk you inhale. you aren't going to be exhaling very much if anything at all.Breathing out???