[samdive]

there was a belief that most BO victims would also have laryngospasm, closing the mouth automatically, however a recent paper from DAN from the breath hold diving conference last year now throws this into question.

We are not talking about closing the internal airway on ascent, the airway should be open, as in the head tipped back slightly so air can travel up the trachea - but about protecting the airway from water entry - so it should be closed to the outside -by holding the mask on and mouth closed.