As the Telegraph explained

 

  We’ve all heard the warning: “In case there is a loss in cabin pressure, yellow oxygen masks will deploy from the ceiling compartment located above you .The same script is repeated on airlines around the world, often ignored passengers listening to music, reading a magazine, or texting on the phones they're about to  China Auto Rubber Seals Manufacturers have to switch to airplane mode. The first thing to note, however, is that crashes from pressure issues on an airplane are exceedingly rare, even if an airplane cabin is punctured, Patrick Smith, a pilot and author of Cockpit Confidential, recently explained to The Telegraph. While it may not sound ideal to breathe in chemicals, it’s most certainly a better alternative to losing consciousness or even dying. Because although oxygen masks and an emergency landing are frightening to passengers, pilots are trained to handle just such situations.. That makes it incredibly important to do exactly as the instructions say: Pull down on the mask, place it over your nose and mouth, and only then assist others around you.

 As the Telegraph explained, most planes carry a concoction of barium peroxide, sodium chlorate, and potassium chlorate .If cabin pressure falls below a certain threshold, the masks will deploy from the ceiling, exposing everybody to the so-called ‘rubber jungle’” Smith said. But just how much time will those oxygen masks buy you? According to io9, each plane carries enough oxygen to last each passenger up to 20 minutes. But understanding how these masks work may one day save your life. Moreover, it’s not exactly oxygen you’re breathing in, but rather a chemical compound that becomes oxygen once it’s burned.. Please make sure to secure your own mask before assisting others. If you refuse to put on the mask you’ll likely suffer from hypoxia, or a lack of oxygen, in under 30 seconds. According to Airbus, passengers have about 18 seconds of “useful consciousness” if a plane loses pressure at 37,000 feet. The plane will be at a safe altitude shortly, and there are several minutes of backup oxygen for everybody. “Should you be confronted by this spectacle, strap your mask on and try to relax.