Everest's Death Zone: Thin Air, Fetal Hemoglobin and Messner's 1978 Climb

SPEAKER_1 (0:00)

Picture this, you are standing at the very top of the world, the summit of Mount Everest.

SPEAKER_2 (0:04)

Quite the view.

SPEAKER_1 (0:05)

Oh, absolutely. But you are 29,032 feet in the air.

The wind is just howling, the temperature is unimaginably cold, and you take this desperate gasping breath.

SPEAKER_2 (0:20)

Right.

SPEAKER_1 (0:21)

Now, what if I told you that the air you just breathed in contains the exact same percentage of oxygen as the air in your living room right now?

SPEAKER_2 (0:28)

It sounds completely made up.

SPEAKER_1 (0:30)

It really does. Like, the oxygen isn't missing. It is right there all around you.

And yet taking a breath in that environment will still, well, it'll kill you.

SPEAKER_2 (0:39)

Yeah. I mean, it sounds like a riddle, but it is a very harsh biological reality.

SPEAKER_1 (0:45)

Welcome to the Deep Dive, everyone. Today we are looking at the biological paradox of the death zone. We're going to figure out how an environment with plenty of oxygen can still, you know, suffocate you.

SPEAKER_2 (0:56)

Exactly.

SPEAKER_1 (0:57)

We want to understand what happens to the human body when it crosses that invisible line in the sky and the incredible lengths we've gone to, both biologically and technologically, to survive it.

SPEAKER_2 (1:06)

And that invisible line, it's actually very specific.

The death zone is a scientifically recognized boundary. It officially begins at 8,000 meters or about 26,246 feet above sea level.

SPEAKER_1 (1:21)

Which is just staggeringly high.

SPEAKER_2 (1:24)

It is. I mean, to give you a sense of scale, out of all the mountain ranges on Earth, there are only 14 peaks that reach this height. Wow.

SPEAKER_1 (1:33)

Only 14

SPEAKER_2 (1:35)

Yeah, they are the 8,000ers. And they are all clustered in the Himalaya and Karakoram ranges of Asia.

SPEAKER_1 (1:42)

The altitude alone is terrifying. But the name itself, you know, the death zone, I mean, who actually looked at that altitude and decided to give it such a morbid official title? Right.

SPEAKER_2 (1:51)

It's a very intense name.

That was actually a Swiss doctor named Edouard Wyss-Dunant. This was back in 1953

SPEAKER_1 (2:00)

Okay, so quite a while ago.

SPEAKER_2 (2:01)

Yeah. He was analyzing data from a previous expedition. And he recognized that there was a physical threshold in the atmosphere where, well, human life could simply no longer be sustained.

SPEAKER_1 (2:12)

So it wasn't just a dramatic nickname?

SPEAKER_2 (2:14)

No, not at all. He originally termed it the lethal zone, actually, because he realized it didn't matter how fit you were.

Above that line, the environment was just fundamentally incompatible with human biology.

SPEAKER_1 (2:27)

And that incompatibility, it all comes back to the paradox we started with. The oxygen is there, right, 20.9% of the air, but the atmospheric pressure is gone.

SPEAKER_2 (2:36)

Yes. That is the key, the pressure.

SPEAKER_1 (2:39)

Because down here at sea level, standard atmospheric pressure is about 1,013 millibars. But you cross into the death zone and that pressure plummets to less than 356 millibars.

SPEAKER_2 (2:50)

It's barely a third of what we're used to.

SPEAKER_1 (2:52)

Right, which fundamentally alters how our lungs function. Because your lungs, they don't actively pull oxygen into your blood, do they?

SPEAKER_2 (2:59)

No, they don't. They completely rely on the weight of the atmosphere to basically push it in.

SPEAKER_1 (3:04)

Okay, let me try a visualization for this, just because understanding this mechanism is so crucial for everything else we're going to talk about.

SPEAKER_2 (3:11)

Sure, go for it.

SPEAKER_1 (3:12)

Think of the air around us like a giant sponge, right? And it's soaked in water, where the water is the oxygen.

SPEAKER_2 (3:17)

Okay, I'm with you.

SPEAKER_1 (3:18)

So down here at sea level, the massive weight of the Earth's atmosphere is like a giant hand, squeezing that sponge tightly. That immense pressure forces the water, the oxygen, out of the air and directly into your bloodstream. Right. But you get up to 8,000 meters and the hand just lets go. The sponge is still soaked with the exact same amount of water, but without that squeeze of atmospheric pressure, you can't get a single drop out of it.

SPEAKER_2 (3:41)

That is, yeah, that perfectly capture the mechanics of it. Because biologically, the oxygen needs that pressure, what we call partial pressure.

SPEAKER_1 (3:50)

Partial pressure, okay.

SPEAKER_2 (3:51)

Yeah. It needs that to cross the membrane in your lungs and bind to the hemoglobin in your red blood cells.

And hemoglobin is the protein that varies oxygen throughout your body.

SPEAKER_1 (4:01)

Right, the transport system.

SPEAKER_2 (4:02)

Exactly. So, without the atmospheric squeeze, the oxygen molecules just sort of bounce off.