What percentage of the air you breath is oxygen?

Answer 1

That totally depends on your definition of life. The short answer: None.

The long answer: Millions of years ago the planet Earth had little oxygen to speak of, and anerobic bacteria (those that didn't breathe oxygen) was the dominant form of life. Then came along what's known as "The Great Oxygenation", in which Earth's atmosphere started becoming more oxygen-based. Once oxygen did appear, the oxygen breathers typically outdeveloped and outbreeded other forms of life, which if I recall correctly has something to do with oxygen being far more efficient for certain biological processes than other elements such as methane.

So it's not that life actually needs oxygen to survive, it's just that oxygen is far more efficient for certain biological processes -- when it's actually available. This does not answer the question. The answer is 18% oxygen at sea level. Source: PADI's Enriched Air Divers Manual

Answer 2

I presume the question is specifically asked about human beings other than about all living things. A healthy person requires to have the oxygen saturation (SpO2) of arterial blood at a minimum level of 92 % to breathe comfortably. If the oxygen saturation drops down to a level lower than 92%, the person will suffer short breath or breathing difficulty when he moves or works. However, if the person remains stationary or inactive, he or she may not feel any significant discomfort at all even when the oxygen saturation level drops down to below 80% although he or she may feel tired and sleepy.

Answer 3

Of course all humans need oxygen in order to survive, it is the main source for breathing. The lowest percentage needed for survival is 16-17%.

Answer 4

oxygen takes up 20 % of the air we breathe

Answer 5

Suprisingly not all humans need oxygen to survive. Some seem to wander around for years brain dead, but still functional. It's a mystery.

Answer 6

For a short time I guess.

Answer 7

17%

Answer 8

44