What Happens To Your Body On a Plane?

20th June 2018

Science

What Happens to Your Body on a Plane?

The ear-popping, skin-drying, head-throbbing and bad-tasting experience of travelling on a plane can be put down to a number of causes. Our bodies go through a lot of changes when we’re flying high, and today we’re looking at what science has to say about that long-haul hangover.

Altitude Sickness

Altitude sickness happens when you arrive at high altitudes, where the oxygen levels are much lower, without the chance to gradually acclimatise. Mountain climbers, who are very susceptible to altitude sickness, are advised to make gradual progress so that their bodies get a chance to adjust. Even then, they usually need an oxygen tank if they’re going very high.

The speed of a plane, on the other hand, doesn’t give your body enough time to acclimatise to the sudden change in pressure and this can cause symptoms of altitude sickness, including:

  • Headaches
  • Fatigue
  • Weakness
  • Dizziness

What Causes Altitude Sickness?

Altitude sickness happens because at higher altitudes, there is less oxygen available for us to breathe in. At sea level, for example, the atmospheric concentration of oxygen is approximately 21% and it is much heavier. This is because at areas close to the ground, oxygen molecules are packed more densely together, allowing us to breathe in more of them.

While the atmospheric concentration of oxygen doesn’t change at higher altitudes, the density of oxygen molecules does. This is because the higher you go, the more spread apart they become. This means that the number of oxygen molecules per breath drops dramatically.

When this happens, it causes the oxygen levels in our bodies to decrease. This causes:

  • Our heart and lungs to work harder
  • Our pulse and rate of breathing to increase
  • A higher production of red blood cells which allow our body to carry more oxygen
  • A change in blood acidity levels, electrolyte levels, and salt and fluid levels

Can a Plane Cause Severe Altitude Sickness?

While your body does experience a form of altitude sickness while travelling on a plane, cabin pressurisation protects against any severe problems by keeping the air pressure inside at a comfortable and safe level for everyone onboard.

It is regulation that the air pressure of a cabin should feel no more than 10,000 feet, although most cabins have the equivalent pressure of 8,000 feet. Even at 35,000 feet, then, the air pressure in the cabin makes you feel as though you’re only at 8,000 feet. This is crucial because if you reached 35,000 feet at normal plane-speed without the help of cabin pressurisation, the air in your lungs would expand so quickly that they would explode. If this didn’t happen, you would most likely suffocate.

Because of cabin pressurisation, the likelihood of feeling severe altitude sickness is quite low. You may still get those headaches, sleepiness and dizziness, but the altitude sickness you will experience is relatively mild.

A woman wearing an anorak standing on high up in the clouds

Altitude sickness is common in mountain climbers who ascend too fast. Our bodies experience a mild form of altitude sickness when we go on a plane because of how quickly we reach higher altitudes. Symptoms include things like headaches and dizziness, but these are only mild because of how cabins are pressurised.

Why Do Planes Make Ears Pop?

One of the characteristic responses our bodies have to high altitudes – whether you’re onboard a plane or driving to Yorkshire in your car – are popping ears. This is also caused by the change in atmospheric pressure.

At higher altitudes, the atmospheric pressure significantly decreases. This is because it is less dense than the air closer to the ground. As we mentioned earlier, the air at sea level is much denser because it has the total weight of the air above pushing down on it. This is why, at sea level, there are more oxygen molecules above any given surface than there are above a similar surface at a higher elevation point. By this logic, atmospheric pressure decreases proportionally to an increase in altitude.

How Does Air Pressure Affect the Ear?

When we’re at sea level – or our accustomed level – air pressure is equal across both ears and travels easily through the eustachian tube. Also known as the pharyngotympanic tube, this is a canal that connects the inner ear (central area behind the eardrum) to the nasopharynx (upper throat and back of the nose). It allows air to travel through this passageway and ensures that the pressure in the inner ear is equal to the surrounding atmospheric pressure.

The eustachian tube opens when the muscles in your jaw or mouth are activated, such as when you yawn or chew or swallow. The rest of the time it is usually closed.

As a plane ascends and descends, the rapidly changing air pressure causes the pressure in our ears to become unequal. When this happens, the trapped air in our inner ear causes the eardrum to expand. This what makes our hearing to go fuzzy because when there is increased pressure on the eardrum, sound is much harder to transmit.

What Causes the Ear to Pop?

The built-up pressure between the inner ear and surrounding atmosphere can be equalised by opening the eustachian tube to allow air to escape. This releases the pressure and gives you that sometimes-painful but always-relieving “pop.”

The reason we sometimes feel dizziness, discomfort or even pain as pressure builds up in our ears during a flight is because the eustachian tube isn’t open enough, or at all. There are several things that can encourage the eustachian tube to open:

  • Swallowing something
  • Chewing something
  • Yawning, or pretending to yawn
  • Pinching the nose and gently blowing

Basically, anything that uses your mouth or jaw muscles will help to open the eustachian tube so that you can release built-up pressure. This is why it is often recommended that you a suck on a sweet or chew gum while taking off or landing in a plane.

A woman looking out a plane window

Our ears pop on planes because as a plane ascends and descends, the pressure in our ears becomes unequal. This is caused by the rapidly changing air pressure around us. When the eustachian tube is closed or not fully open, this pressure builds up and causes discomfort as well as a loss of hearing. The eustachian tube can be opened by moving the mouth muscles, such as chewing, yawning or swallowing.

Dehydration

At higher altitudes, air is drier and less humid. This is because the thinner atmosphere, which we have established is much less dense, cannot hold as much water vapour as the denser air at sea level.

When you’re on a plane at high altitudes, you exhale moisture-rich air and inhale dry air. It is easy to become dehydrated if you don’t drink water during a flight because the water you lose isn’t being replaced. Dehydration can lead to dry skin, chapped lips, headaches and irritability. So if you’re planning on taking a long trip to Australia any time soon, make sure you take a bottle of water and a good moisturiser!

‘Plane Food is Terrible’ is a Myth 

Yep, you read that right. The reputation that planes have for their bland-tasting food may not actually be their fault. It’s actually all to do with your taste buds and how they are affected by the atmospheric pressure.

How Do We Taste?

The flavour of food is detected by a working relationship between our taste buds and smell. When we chew, we produce a lot of salivae which breaks the food down and transfers the flavour to our taste buds. Here, tastants are detected. These are taste-provoking chemical molecules.

Meanwhile, our nose is detecting the odorants in food by using the membrane along the roof of the nose to send messages to the olfactory bulb. This collects the information from your taste buds and nasal cavity to give you a perception of flavour.

Therefore, your taste buds as well as your smell play crucial roles in the detection of flavour. In fact, 80% of what we taste is actually caused by smell. Unfortunately, taste and smell are the first 2 senses that are numbed during a flight.

Why Does Food Taste Bad on Planes?

The receptors in our nose are what help us to detect and identify smells. We have over 100 million specialised receptors on the roof of our nasal cavity, and these are covered by a thin layer of mucus that dissolves different scents and uses chromatography to separate their components.

The dry air caused by low atmospheric pressure causes the mucus in our noses to evaporate quickly. It also causes the membrane along the roof of our nose to swell. This results in a decreased sense of smell which impacts heavily on our ability to taste.

In a similar way, our taste buds are numbed during a flight because the dry air decreases our moisture levels, causing our production of saliva to drop. Therefore, it isn’t the food on the planes that tastes bad, but rather the effects of low atmospheric pressure that limits our ability to taste things properly.

Wooden spoons with spices

The reason why plane food tastes so bad isn’t because of the food itself, but because of how the change in atmospheric pressure numbs our taste buds and sense of smell.

With all of this in mind, it really shows how incredible the inhabitants of Machu Picchu were to thrive as a civilisation that was nearly 8,000 feet in the air. So the next time you’re getting on a plane, a bit of chewing gum, water, moisturiser and flavour-enhancers will make that trip a whole lot smoother!

Leave us a comment, we’d love to hear from you...