Oxygen can be lethal

Can a person get by on pure oxygen to breathe?

The air we breathe consists of only one fifth oxygen and almost four fifths nitrogen. 100 percent oxygen would be a completely different situation. Nevertheless, this is not a problem in the short term - pure oxygen is also used in emergency medicine. In spaceships, too, there is at least an increased concentration of oxygen.

That is, the person can withstand it temporarily. But it's not healthy in the long run. This is especially true when the oxygen is supplied via compressed air cylinders. The higher the pressure, the more harmful the oxygen becomes. Because normally the oxygen atoms form pairs - two atoms always form a molecule, hence the chemical formula O2. At higher pressure, on the other hand, these pairs increasingly separate and oxygen radicals are formed; these can damage the lungs and brain. One then speaks of oxygen poisoning. So the pressure is a very important factor.

Astronauts in spaceships often live in oxygen-enriched air, but the pressure is reduced. It is therefore not as dangerous as when divers supply themselves with oxygen from a compressed air cylinder - and this may still be a few dozen meters below the surface of the water, where the pressure is much higher anyway.

For these reasons, pure oxygen is normally only used for resuscitation in emergency medicine for a very short time. Otherwise, the human body is already adapted to the natural oxygen content of 21 percent. An atmosphere with significantly more oxygen would also not be desirable, because oxygen is a very reactive gas. And if the atmosphere had significantly more oxygen, the risk of forest fires would be much higher, for example.

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