The mask covers both your nose and mouth. One-way valves prevent exhaled air from reentering the oxygen reservoir.
A non-rebreather mask is used in emergency situations to prevent hypoxemia, also known as low blood oxygen. Conditions that disrupt your lungs’ ability to uptake oxygen or your heart’s ability to pump blood can cause low blood oxygen levels.
If your blood oxygen levels drop too low, you can develop a condition called hypoxia, where your essential tissues become oxygen-deprived.
A non-rebreather mask may be used after traumatic injury, smoke inhalation, or carbon monoxide poisoning to keep blood oxygen levels within a normal range.