What Happens If Your Oxygen Mask Doesn't Inflate on a Flight? (Video)

Whether you’re paying attention or not, that pre-flight safety demonstration is there for a reason.

Everyone is familiar with this must-do part of your flight, and hopefully, most of us have absorbed the information from these demos so many times that the idea of putting on our safety belts and using our oxygen masks in case of emergency are like second nature to us.

A flight attendant demonstrates how to use the emergency oxygen mask
Robert Alexander/Getty Images

Of course, there are several people out there who, no matter how often they fly, still aren’t quite sure how to operate those masks. This is mostly because they’ve (luckily) never had to do it in a real-life situation, but knowing the basics about oxygen masks could be a huge benefit to you, and it could even save your life.

This was especially apparent back in 2018, when a tragic accident on a Southwest Airlines flight caused damage to the fuselage to the plane, leading to the death of one passenger. In this instance, the plane automatically deployed oxygen masks due to the sudden change in air pressure in the cabin.

Unfortunately, photos from the scene show passengers loosely wearing their masks, with many covering only their mouths.

Think back to that pre-flight demo, and you’ll find that it always reminds you to cover your nose and mouth.

But this actually isn’t the only confusing part about using an oxygen mask. As the pre-flight safety demo mentions, passengers often notice that these masks have a bag attached to them, but it might not actually inflate. Luckily, this isn’t any indication that the mask is dysfunctional, although it can give a passenger some unnecessary anxiety if they aren’t informed.

Why We Need Oxygen Masks

First of all, if you’re not well-versed in the purpose of oxygen masks on planes, you may have wondered why there’s a need for them in the first place. After all, there’s air on the ground, air in the plane, and air outside the plane, so wouldn’t you be able to breathe regardless?

Well, technically no. Planes often cruise at an altitude above 36,000 feet, which is high enough so that the air is particularly thin (read: less oxygen), but not so thin that combustion engines can’t work. This altitude is too high for people to get sufficient oxygen, so the air in the cabin is pressurized so that it's similiar to the air pressure you’d find around 6,000 to 8,000 feet (so there’s a big difference in the amount of oxygen you get on a plane versus the amount you get on the ground in the first place). Of course, were the cabin to lose pressure, the lack of oxygen would likely cause passengers to become nauseous, get headaches, become confused, or even pass out, which can lead to death.

So, oxygen masks are deployed to help passengers breathe, at least until the plane is at an altitude where it’s safe to take them off, usually when the pilot has steered the plane into a “safe zone” at a much lower altitude. Oxygen on board usually only lasts about 15 minutes, according to The Huffington Post.

Creating the "Oxygen"

Even though demonstrations call it “oxygen,” it would actually be very difficult and heavy for an aircraft to carry a bunch of oxygen tanks on board in case of an emergency. Instead, according to The Telegraph, the oxygen released into masks is created using certain chemicals, including barium peroxide, sodium chlorate, and potassium chlorate. These chemicals are kept in the panels above each row of seats and are mixed together when the oxygen masks are deployed, a process otherwise known as “burning.” Even though it’s created by chemicals, you are still breathing actual oxygen because oxygen is created as a byproduct of this chemical combination.

To Inflate or Not Inflate

So now you know what the oxygen masks are for, but what about that mysterious bag? According to Mental Floss, the bag actually can inflate, but sometimes it does not because of how you’re breathing. Oxygen masks you find on planes are called “continuous flow” masks, which means oxygen is flowing constantly, whether or not you’re inhaling.

Fun fact: The crew usually have different masks that only release oxygen when they inhale, in order to waste less air, according to Mental Floss.

Because there’s a constant flow of breathable air, the bag will actually inflate and store excess oxygen while you exhale. These masks have a one-way flow, so the air you exhale, ideally, vents out through a valve rather than going back down the tube, according to Mental Floss.

If you breathe very fast or very deeply, the bag won’t get a chance to inflate with excess oxygen before you inhale again, so it will deflate. Don’t worry if your seat neighbor has an inflated bag and you don’t. Both of your masks are working exactly how they should.

How to Properly Use Your Mask

If you’re not entirely familiar with the standard pre-flight safety demonstration, it’s important to know how to properly use your mask in the event that you truly need it.

First, it’s important to remember to make sure your mask is correctly situated on your face before you help anyone around you. This may seem like an individualistic, “survival of the fittest” policy, but frankly, you’re no good to the person you’re trying to help if you can’t get oxygen into your lungs yourself.

Next, after the masks have dropped down and you’ve pulled yours closer to you, place the elastic band around your head in order to secure the mask (the yellow piece) on your face. Remember to cover both your nose and mouth. The elastic can be pulled tighter by tugging on the ends attached to the mask itself. This should create a good seal around your face so no oxygen leaks out.

After your mask is snugly on your face, you can breathe normally, preferably through your nose, and try to remain calm. As the old saying goes, “Although the bag on the oxygen mask may not inflate, oxygen is flowing to the mask.”

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