A non-rebreather mask is a medical device that helps deliver oxygen in emergency situations. It consists of a face mask connected to a reservoir bag that’s filled with a high concentration of oxygen.

Non-rebreather masks are used to deliver oxygen therapy to people who require high-concentration oxygen but aren’t in need of breathing assistance. They’re considered low-flow oxygen delivery systems.

Answer: On typical airliners oxygen generators will last 10 to 14 minutes. That is more than enough time to descend to 10,000 feet or the lowest altitude above the terrain. Airplanes can descend very ...