People who travel long distances by air travel at altitudes of 9,000 to 12,000 meters. Through technology that creates a kind of artificial atmosphere, the pressure in airplanes is equivalent to that at an altitude of about 2,000 meters to 2,500 meters, which is about as high as St. Moritz in Switzerland. Studies have shown that around half of all passengers suffer from oxygen deficiency – but not everyone notices.
How important is oxygen?
Research by Belfast anesthesiologists published in the journal Anaesthesia (vol. 60, p. 458, 2005) provides troubling results for air travelers. Fifty-four percent of passengers had blood oxygen levels that were too low, 93 percent – the normal oxygen concentration is 97 percent. At first glance, that seems like only a small difference.
15 liters per hour – oxygen is essential for life
The chemical formula of oxygen is O
2
, because as an unbound gaseous substance, it normally consists of a diatomic molecule. It is more abundant on Earth than any other chemical element, but it cannot be seen, smelled, or tasted. Eighty-nine percent of water and 50 percent of the earth’s crust are made up of oxygen, which plants produce with the help of leafy greens and light. The air we breathe is composed of about 80 percent nitrogen and 20 percent oxygen in the form of gaseous molecules. Due to the Earth’s gravitational pull, most air molecules are located near the surface of the Earth. Towards the top, air becomes thinner and thinner, and so does oxygen. This means that the fewer the molecules, the lower the air pressure. On average, we consume about 15 liters of oxygen per hour; so on average, humans breathe in and out 19,000 liters of air every day. Breathing activity must be uninterrupted because oxygen cannot be stored in the body like other substances.
Artificially increased pressure in aircraft
Since few people are as fit as mountaineer Reinhold Messner, who can do without oxygen at altitudes well above 8,000 meters, the pressure must be artificially increased in airplanes. The law therefore requires civil airlines to equip their aircraft with pressurized cabins. Even if you breathed 100 percent oxygen, you could not survive at altitudes above 13,500 meters.
5 Tips that can help combat oxygen deprivation
- How quickly an airline passenger becomes oxygen deficient depends on his or her general state of health. For example, smokers have comparatively less oxygen in their blood than nonsmokers. Minimizing cigarette consumption a week before a long flight could help keep better oxygen levels during the flight.
- Those facing a flight should avoid starting fast mountain climbs or long diving expeditions in the days leading up to it. After such activities, which severely limit the oxygen supply, you should take a few days so that the body can accumulate enough oxygen in the blood again.
- Especially athletes have fewer problems with oxygen deficiency on the plane, because they automatically have a better oxygen saturation in the blood. So exercising outside the week before a flight can help enrich oxygen in the body, but won’t do much if you never exercise otherwise.
- Another tip is to sleep. While we sleep, we use much less energy and also oxygen, because our body is put into a state of rest. So the easiest way to use less oxygen while flying is to sleep as much as possible.
- If the cockpit just allows it, get up and walk a few steps! By breathing deeply and slowly at the same time, you can further improve oxygenation. And, moving your legs regularly also prevents thrombosis on long-haul flights.
What happens when there is a lack of oxygen?
In the Belfast study, doctors concluded that 54 percent of passengers (84 people between the ages of 1 and 78 were tested) had too little oxygen in their blood. This O
2
-deficiency could explain why many travelers felt unwell or ill after long flights, especially if they had drunk too little, moved very little and had low humidity.
Compensation of oxygen deficiency
A healthy organism compensates for lower oxygen levels by making the heart beat faster and the vessels constrict. Heart patients and people with anemia should therefore be sure to consult a doctor before traveling by air. Oxygen deficiency, also called hypoxia, is a medical condition that develops at high altitudes. Even in the lowest layer of the atmosphere, the troposphere, the air becomes so thin at 3,900 meters that oxygen deficiency symptoms can occur.
Symptoms of oxygen deficiency
Medical experts Eckhart Schröter and Torsten Hahne describe numerous symptoms experienced not only by commercial pilots, but also by paragliders:
- Rapid and deep breathing (hyperventilation).
- Tingling sensation in the feet, hands and face
- Dizziness
- Changes in color vision
- Narrowing of the visual field
- Euphoria and drowsiness
Is air travel a concern for pregnant women?
A fetus needs plenty of oxygen for trouble-free development. To find out whether this is given at high altitudes, Professor Renate Huch of the University Hospital of Zurich closely examined ten pregnant women on 20 flights across Europe. Here, the all-clear was given: both during takeoff, landing or at full flight altitude, the embryo‘s heart beat just as fast as it did at ground level – a sure sign that it was optimally supplied with oxygen.
Oxygen masks – a bad sign?
This is probably what every passenger is afraid of: the oxygen masks falling off – a sure sign that something is wrong. What happened. Airplane cabins are basically airtight. At high altitudes, where there is very low air pressure outside, the pressure is artificially kept at a normal level. Normal air pressure at sea level is about 1,013 hectopascals. The air pressure decreases with altitude and, according to a rule of thumb, is approximately halved after every 5,000 meters. If the aircraft is flying at cruising altitude, the plane is inflated like a balloon, so to speak, which means that the pressure inside the cabin is higher than the pressure of the surroundings.
Pressure drop triggers oxygen masks
If the pressure now drops, the oxygen masks, which are installed above each seat, are automatically triggered. Even a leaky valve or a small hole in the aircraft can allow air to escape very slowly and imperceptibly. For this reason, there are several sensors that constantly check the condition inside the cabin. The oxygen masks are therefore triggered very early. At this point, there is still no danger to the passengers. The pilots must now bring the aircraft as quickly as possible from the cruising altitude in a descent to an altitude that allows problem-free breathing even without oxygen masks. At the latest, it is no longer necessary to wear oxygen masks at altitudes below 4,000 meters.
