It's me, Destin. Welcome back to SmarterEveryDay. When you're in a jet, if the

cabin depressurizes, they drop this little mask out of the top.

What happens if you're in a depressurized cabin and you're up above 15,000 feet [4,500m]

and you drop your mask? Something called hypoxia takes effect and you got to do

something about that.

Let's get smarter every day.

You've heard the flight attendants say this before,

“Secure your own mask before helping others.” But why?

Why did they say that? Is the 30 seconds it takes to put

on a kid’s mask next to me really that important?

15 years ago I learned the answer to this question when I was selected to

participate in NASA’s Reduced Gravity Student Flight Opportunities Program at

NASA’s Johnson Space Center. Before I got to ride in the Vomit Comet I had to

undergo physiological training in a hypobaric chamber at the neutral

buoyancy lab.

Fast forward to now. Today, astronaut Don Pettit is scheduled to renew his hypoxia

training certification and I asked him if it would be okay if I tagged along

let me swim a few laps with him over the International Space Station mock-up in

the neutral buoyancy lab before we headed over next door for Don’s training.

– You look like something the dog dragged in. – I feel like it, too. The purpose

of hypoxia training is to let astronauts and aviators know when their brain’s

about to stop working correctly, which is very, very important. If you’re at a high

altitude in an airplane, the air is thinner but the cabin is pressurized, so

your body gets enough oxygen to operate. To simulate cabin depressurization, NASA

puts its astronauts in a chamber at sea level and then pumps the air out to

thin it out, so that it simulates a higher altitude.

Don’s training starts with class work focused on understanding the specific

signs and symptoms of hypoxia in his own body.

The goal of this training is to understand your own physiological symptoms so that

you can take action quickly.

For example, Don said he experiences tunnel vision and air hunger, but I

remember for my training 15 years ago that get really happy and start to

tingle all over

– I can't take you seriously because this is what you look like.

– What do you mean? I look perfectly normal. – [giggling]

This is the experiment we're going to do: Don and I are both going to enter the

hypobaric chamber at the same time and fly to FL250, at which point we are

going to remove our masks and start to experience the effects of hypoxia.

Don is the control. He’s a trained astronaut who recognizes the symptoms

for hypoxia and immediately corrects for them.

I, on the other hand, am under the direct supervision of a NASA flight surgeon and

after I notice the effects of hypoxia,

I’ve asked if I could delay for about one minute so we can better understand

the physiological effects of not immediately putting your mask on.

OK, here we go, we're getting set up.

While Jerry gets me situated, I’m going to talk about the two types of

decompression: Number one, rapid decompression this is like being inside

of an explosion.

You dump all your pressure instantly, all the moisture condenses out of the air,

you’re suddenly in a cloud. Very scary, very violent

Yeah, we’re not going to do that. What we're going to do is simulate a slow,

steady leak. We’re going to start at sea level and ascend at 5,000 feet [1,500m] per minute

all the way up to 25,000 feet [7,500m], or as aviators call it, flight level 250

OK, I want to make one thing abundantly clear. We performed this demonstration at

25,000 feet [7,500m]. I had about three to five minutes of consciousness left.

However, most airliners travel at 35,000 feet [10,000m].

Look at this chart: There is way less oxygen up there.

At 35,000 feet [10,000m] you literally have seconds of useful consciousness at that altitude.

You can go from a normally rational person to someone so helpless you can

even save yourself if your life depends on it.

I don’t-

I don’t wanna die

I don’t tell you this to scare you. I simply want you to understand the

physiology behind that little preflight announcement.

“Put your mask on first before helping others.”

Look, I don’t want to get too deep or philosophical with this,

but I think there's a neat metaphor here.

Sometimes it’s easy for me to see the problems in other people and focus on

that and I get so carried away with fixing other people that I forget that I

have a problem too.

And I think that’s what’s so cool about this demonstration.

Sometimes you just got to put your mask on first and get yourself sorted

before you can help others.

– So thanks again for saving my life, by the way. – You're welcome, it was an honor and a pleasure.

– It was great. – [Inaudible] all the time.

–Thank you.

There you go, now we learned why you need to put your mask on first

before you help other people. You don’t want to get hypoxia.

I'm Destin

you’re getting smarter every day, have a good one.

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I want to say thank you to the awesome people at NASA’s neutral buoyancy laboratory.

They kept me super safe, super informed and they educated me and made me smarter every

moment I was with them. That was really awesome. Thank you so much, guys

Anyway, I’m Destin you’re getting smarter every day. Have a good one.

–What’s the deal here, Don? – Well I cut the regular lens off of the goggles

–OK – and then I took an old pair of glasses and I cut the plastic to fit my

goggles and then I glued them on. – You basically MacGyvered your own goggles,

so that you had correction underwater.

– That’s right. – That’s pretty good.