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An orinasal mask, oro-nasal mask or oral-nasal mask is a breathing mask that covers the mouth and the nose only. It may be a complete independent item, as an oxygen mask, or on some anaesthetic apparatuses, or it may be fitted as a component inside a fullface mask on underwater breathing apparatus, a gas mask or an industrial respirator to reduce the amount of dead space. It may be designed for its lower edge to seal on the front of the lower jaw or to go under the chin.
An orinasal mask may carry a filter for ambient air, or be supplied from a user-carried breathing gas supply or a remote gas supply using a supply hose. Another application is the resuscitation pocket mask, which is used as an infection barrier between the rescuer and a non-breathing casualty for expired air resuscitation.