BIBS mask for oxygen provision in a hyperbaric chamber
Sealing to the front of the lower jaw

An orinasal mask, oro-nasal mask or oral-nasal mask[1] 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.


Stand-alone orinasal units

Simple orinasal face mask for oxygen therapy at normal atmospheric pressure
CPR pocket mask
Bag valve mask. Part 1 is the flexible mask to seal over the patients face, part 2 has a filter and valve to prevent backflow into the bag itself (prevents patient deprivation and bag contamination) and part 3 is the soft bag element which is squeezed to expel air to the patient

Internal components of full face units

Where an orinasal mask is used as an internal component of a fullface mask, helmet or hood, its function is generally to reduce dead space, allowing effective use of demand supplied gas or a breath driven rebreather loop. They are not necessary if the breathing gas supply is abundantly in excess of physiological requirements in a free-flow or powered rebreather loop. They also function to minimise contact of high humidity exhaled gas with the internal surfaces of the viewports, and thereby reduce condensation on the viewports in cold conditions, which adversely affects the user's view of the surroundings.[3][4][5]


The construction of an orinasal mask depends on the application. In the most basic cases a disposable mask may be made of porous paper or non-woven fabric held in place by two elasticated webbing straps around the back of the head. For more critical applications and where re-use is intended, soft flexible polymers or elastomers are generally used for the seal. The straps may be synthetic rubber or elasticated woven webbing, and the frame may be moulded plastic, to which accessories such as filters and valves can be fitted. Orinasal masks which are fitted inside full-face masks or helmets are generally made of synthetic elastomers, commonly silicone rubber, and are often a replaceable item.

See also


  1. ^ a b "Ultralite 2 BIBS Mask (DE-MDS-540-R0)" (PDF). Divex. Retrieved 25 September 2018.
  2. ^ "A Lightweight, and Extremely Robust, Built In Breathing System for Hyperbaric Chambers" (PDF). Aberdeen, Scotland: C-Tecnics Ltd. Archived from the original (PDF) on 25 September 2018. Retrieved 25 September 2018.
  3. ^ a b "Breathing Apparatus: Keeping our people safe from toxic smoke and fumes". Retrieved 12 March 2020.
  4. ^ "Neptune Space full face mask owner's manual rel.9.3" (PDF). Ocean Reef. Retrieved 12 March 2020.
  5. ^ a b Larn, Richard; Whistler, Rex (1993). Commercial Diving Manual (3rd ed.). Newton Abbott, UK: David and Charles. p. 127. ISBN 0-7153-0100-4.