Q. How much oxygen does a person consume in a day?
A. The average adult at rest inhales and exhales something like 11,000 litres of air per day.
The air that is inhaled is about 20 per cent oxygen and the air that is exhaled is about 15 per cent oxygen, so
about 3 to 5 per cent of the volume of air is consumed in each breath and converted to carbon dioxide. So a human uses up between 550 and 350 litres of oxygen a day, or about a quarter of a litre per minute.
The rate of oxygen consumption rises significantly depending on how much exercise you are getting.
A person busy at work might use as much as five times that while an athlete running a marathon could consume more than 20 times that.
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