UPR.C | How High is High?

So we mentioned Denver, Colorado, which is famously called “The Mile High City”, because it is situated on high plains just before the Rocky Mountains begin. 

Because of this, the city is at an altitude of roughly one mile, or 5,280 feet (1609 metres), above sea level. If you go to visit Denver but you live in a place a little closer to sea level, say, Boston or New York, you might find that you have to breathe a bit deeper and you’ll probably get a bit sleepy for the first couple of days.  This is because the air pressure is lower at five thousand feet than it is at sea level, and your body isn’t pulling in as much oxygen. The good news is that the human body is really good at adjusting to different environments, so within a couple of days you’ll have acclimatized to the new environment.

This is why people can live way up near Mount Everest and other high altitude places in the world, but you’ll need some time to let your body get used to it if you go up to visit them if you live in lower altitudes.  If you go to Denver, it’ll take a couple of days, but if you head up to Mount Everest, you’ll have to live at the Base Camp for four to eight weeks for your body to adjust to living at seventeen thousand, six hundred feet.  But the people who live there have adapted to live at these high altitudes over generations and generations of passing along the genes of people who have survived these harsh conditions.

So what does all this have to do with your ears popping and all of that yawning on a commercial airliner?

Up in the Air

Okay, when you fly in a plane from, say, Boston to Denver, the plane you’re travelling in flies at anywhere from about eight thousand, eight hundred to nine thousand, seven hundred meters (around twenty-nine thousand to thirty-two thousand or more feet) above sea level, but you’re not feeling the outside pressure.  The reason for this is pretty simple – you wouldn’t survive. The human body can really only survive on its own up to about twenty-two thousand feet without some help. Planes fly at these altitudes because the thinner air allows them to travel faster and conserve fuel because there is a lot less wind resistance, but since people can’t survive at this altitude, they pressurize the interior of the plane to make it nice and comfortable for you.

Basically, the plane is a flying pressure vessel – that’s why it needs those big thick doors you see as you enter the plane.

When the plane takes off, you’ve probably noticed that it climbs pretty quickly.  As it rises, the air pressure outside is changing rapidly, so then the pressure inside the plane has to change rapidly, too, and they try to keep the pressure to about seventy-five percent of the atmospheric pressure outside the plane.

So what’s happening to your ears?  We’ve spent quite a bit of time talking about your lungs, but your ears are also affected by changes in pressure because your ear drums separate your inner ear from the middle ear chamber.

When the plane takes off and the air pressure drops, the pressure inside your ear is still where it was when you boarded and it sort of bulges out.  This can cause discomfort that you feel. When you yawn, or make a yawning motion, this opens the eustachian tubes that connect the middle ear to the pharynx, which is in your throat, and relieves that pressure.  Similarly, if you chew gum or suck hard candy, this can help get those tubes open by performing the same motions as yawning. The same thing happens in reverse as you descend toward the airport on the opposite end of the trip and the air pressure increases outside of the plane and hence inside as well.

Bet you never realized your body was doing so much while you were just sitting there watching the world go by through the window in seat 23 A, did you?

But what happens when you dive down into the ocean?  Ever taken a deep dive in a pool or lake or the sea and felt your ears start to pop there, too?