Many people find chasing through the clouds thousands of meters above the ground in a metal tube not too reassuring. Nevertheless, airplanes are one of the safest means of transport of all. But what is the situation apart from the accident statistics?

INFECTIOUS DISEASES

Airplanes are notorious for being breeding grounds for bacteria. Unjustly so: Although airplanes contribute to the spread of epidemics, this is mainly due to the movement of people from one country to another.

It is not proven that when someone is inside the airplane, the danger of his or her getting infected is higher than standing in the queue at security control, for instance.

The risk of infection when flying is no higher than in an average office building. According to the WHO, the air in an airplane is completely replaced 20 to 30 times within an hour. For this purpose, some fresh outside air is sucked into the aircraft. 

The rest of the air is recycled. In most modern aircraft, the air passes through a HEPA filter. These filters are so fine that they trap even viruses and bacteria. 

Read more: Coronavirus: From bats to pangolins, how do viruses reach us?

No influenza viruses found in the aircraft

For a study from 2018, researchers collected nearly 230 air samples and surface swabs on 10 flights. In the subsequent analysis, no flu or cold viruses were found. And this despite the fact that the flights took place in the middle of the flu season.

It is more difficult if you are sitting within two rows of seats next to a sick fellow passenger. If there is a person coughing and sneezing in the immediate vicinity, the risk of being infected is just as high as in a bus or car.

Disinfectant and face mask protect against infection

If you want to protect yourself, you should have disinfectant in your hand luggage. Before you eat or drink something, you should wipe your hands and the folding table with it.

If you have a cold yourself and want to protect others, you can think about a face mask. It catches the droplets from our throat when we cough or sneeze. The mask may also gives the person sitting next to you a feeling of security.

Better than that: highly infectious people should postpone a planned flight. Airlines are also allowed to exclude people with an acutely contagious disease from boarding. 

Read more: Why coronavirus fears are disproportionate compared with other health risks

COSMIC RADIATION

The earth is constantly bombarded with a stream of high-energy atomic particles. They come from the sun and from the depths of the universe. The totality of these particles forms the so-called cosmic radiation.

The Earth's magnetic field and atmosphere act like a natural shield and intercept many of the particles. This means that the closer you are to the surface of the Earth, the lower the radiation.

The shielding is highest at the equator and lowest at the polar regions. This is due to the shape of the magnetic field and the fact that the atmosphere is thinner above the poles.

No health hazard for occasional pilots

The dose of radiation that one receives during a flight therefore varies not only depending on the altitude and duration of the flight, but also on the route.

According to the Federal Office for Radiation Protection, however, high-altitude radiation is not dangerous for occasional pilots, and it is even harmless for pregnant women and small children.

According to this, the effective dose for a flight from Frankfurt to New York and back, for example, is 100 microsievert. Since the average annual radiation exposure averages 2100 microsieverts, this represents an increase of only 5 percent.

However, this also shows how much frequent flyers and flight personnel are exposed to increased radiation. Therefore, health authorities are looking into radiation as a potential health hazard for flight personnel. 

Read more: Satellites to observe reconnection of magnetic fields

AIR PRESSURE

The cruising altitude for long-haul flights is between 11 and 12 kilometres. However, the air pressure inside the aircraft is controlled and corresponds to the air pressure at 2000 meters above sea level.

According to the WHO, this leads to less oxygen being absorbed into the blood. This is not a problem for healthy people.

However, for some people with heart and lung diseases or blood anomalies, the lower oxygen level can become a problem. They either need an extra oxygen supply or they should avoid flying.

Pressure on the ears

The comparatively low air pressure can also lead to problems with the ears. Chewing gum, swallowing and yawning help to equalize the pressure.

If that doesn't help during descend, there is also the so-called Valsalva method: keep nose and mouth well closed while trying to breathe out strongly.

And if you have a sinus infection, it is better to avoid flying.

THROMBOSES

According to the WHO, one in 6000 passengers suffers from travel thrombosis after a long-haul flight. This leads to the formation of blood clots in the veins of the lower legs or the pelvic area.

Signs are swelling, redness and severe pain.

The lack of exercise is responsible for the formation of the thrombosis. This applies to airplanes, trains and long bus trips. There is not enough space in the narrow rows of seats.

Muscle movement is an important factor in keeping the blood flow moving. The blood vessels in the legs can become blocked on long-haul flights.  

Restricted movement is a problem especially for risk groups

Some people have an increased risk of thrombosis. These include pregnant women, women who use hormonal contraception, people who are overweight, cancer patients and people with a genetic predisposition to thrombosis.

According to the WHO, there are no preventive measures for thromboses.

As far as flight conditions permit, a little exercise can do no harm. Many airlines also distribute instructions for muscle exercises to keep the blood flow going.

DEHYDRATION 

The air humidity in airplanes is on average 20 percent. That is about half of what most people find pleasant. The low air humidity leads to dry skin on the face and dry eyes.

Moisturising creams and eye drops help here. Anyone who is used to wearing contact lenses should preferably switch to regular glasses on a long-haul flight.

According to the WHO, it has not yet been proven that the external lack of moisture also leads to internal dehydration. Drinking plenty of water on the plane can still do no harm.

But please do not drink the water from the bathroom sink on board! Although the quality and drinkability of the on-board water will be tested regularly by aircraft operators, the tap water on board should only be used to wash hands. This is especially true for people with immune deficiencies.

In this sense: Have a good flight!