"We Wish You A Pleasant Flight"

Other than tense muscles, dehydration and sleeplessness, air travel can affect our bodies in many other ways – here’s what you need to know.

Portrait of Tammy Strobel

When we take a plane trip our body takes a journey that affects our cardiovascular system, our sensory perceptions and possibly even our immune system. In the space of just a few minutes, your body is shot into an environment whose conditions resemble those found at altitudes of 2.5 km above sea level. Meanwhile, the air humidity falls to around 10 per cent or lower. If that’s not enough, the airflow around your body can sometimes drop to an icy 5 C when it leaves the air-conditioning vents. So conditions are indeed extreme when you’re on board an aircraft, but what effects do they have on our well-being? Read on to find out more.

“Healthy” Aeroplanes

“It is possible to design a plane whose on-board conditions match those on the ground,” says the president of the German Society of Aerospace Medicine, Professor Jochen Hinkelbein from the University Hospital of Cologne. But this would require an aircraft’s aluminium skin to be much thicker, and thus weigh several tonnes more, in order to withstand the higher air pressure inside. Airlines would also need hundreds of extra kilograms of water per flight to keep the air humidified.

“The on- board conditions are a compromise between wellbeing on the one hand, and profitability and eco-friendly practices on the other. Long-haul flights do not pose a problem for healthy people – which is why relatively little research has been conducted in this field,” Professor Hinkelbein adds. “Only now that flying has become a mass phenomenon, with a growing number of older, less healthy people travelling, is a greater interest being shown.”

Facing The Pressure

Our body is similar to a pressure hull. On the ground, the external air pushes against it at about the same intensity as it pushes back from inside. In the air, this balance suddenly falls out of sync – the pressure in the digestive system is higher than the lowered air pressure. The gases in the stomach expand, causing bloating and flatulence, which try to find a way to escape. Pain in the ear or behind the forehead, felt particularly by those suffering from colds, is another consequence of differing pressure between your surroundings and your head during take-off and landing.

Thirst Trap

Without people, the cabin air humidity would only be two per cent, but the combined breathing and sweat of the crew and passengers increase this to 15 per cent. During a flight, our body becomes parched – we can lose up to 1.5 litres of fluid for every three hours of flying. Up to 37 per cent of the skin’s moisture evaporates, which can be seen in the callouses on our fingers we get while flying, while contact lens wearers often suffer from eye irritations.

Radiation Safety

The higher above the earth’s surface you are, the less the atmosphere protects you from cosmic radiation, though protection is higher over the equator compared to the Poles.

An eight-hour flight increases the 2,100 microsieverts of radiation naturally absorbed by humans from their surroundings by around five per cent – 20 hours on a plane is roughly equivalent to having a head X-ray. While this is not considered dangerous, crew exposure to radiation is monitored.

Cardiac Concerns

Fainting is the most common medical emergency that occurs on board. Susceptible people are also at risk of high blood pressure, cardiac arrhythmia and blood clots. This is due to a lack of oxygen in the blood and a lack of exercise during the flight. Without muscular strength, leg veins are unable to properly transport blood back to the heart.

TIP:  If you have a medical condition, always consult your physician on your fitness to travel. Depending on the airline, some conditions may require you to get medical clearance before you fly. Singapore Airlines, for example, will provide special attention or medical equipment on board their flights – you simply have to submit a Singapore Airlines Medical Information Form (MEDIF) at least five days before your flight.

Immunity Down

Initial studies on the impact of oxygen deficiencies on the immune system have found that some proteins change the way they work in these cases. Thus, the notorious ‘aeroplane cold’ could not just be due to the air-conditioning system, but also to the body’s altered immune response to germs.

Eye See

The photoreceptors in our eyes need lots of oxygen – and they start showing signs of deficiency from altitudes of just 1,500 metres. This reduces our ability to see sharply in dimmed light by 10 to 15 per cent.

Cry Baby

Studies have found that 15 per cent of men and six per cent of women cry more when watching in-flight entertainment compared to on the ground. According to researchers, this is due to the heightened emotional situation – such as being away from home or excitement about the trip – but possibly also due to the slight lack of oxygen in the body.

My Reading Room

You lose more than two litres of fluid during a 10-hour flight, so stay hydrated!


Here’s where you can get more information:

Civil Aviation Authority of Singapore www.caas.gov.sg/ public-passengers/before-yourflight/cabin-safety.

Singapore Airlines www.singaporeair.com/en_UK/sg/ travel-info/special-assistance/