A non-rebreather face mask fits over your mouth and nose and attaches with an elastic band around your head. The mask is connected to a plastic reservoir bag filled with a high concentration of oxygen. The mask has a one-way valve system that prevents exhaled oxygen from mixing with the oxygen in the reservoir bag.
When you inhale, you breathe in oxygen from the reservoir bag. Exhaled air escapes through vents in the side of the mask and goes back into the atmosphere.
Non-rebreather masks allow you to receive a higher concentration of oxygen than with standard masks. They’re generally only used for short-term increases in oxygenation.
Non-rebreather masks aren’t commonly used because they come with several risks. Disruptions in airflow can lead to suffocation. You can potentially choke if you vomit while wearing the mask if you’re sedated or unconscious. A healthcare provider usually remains in attendance during use of this type mask.