For human survival, approximately what percentage of air must be oxygen?

20.9 percent

Around 78% of the air is nitrogen gas, and only 20.9% is oxygen.

Explanation:

20.9 percent

Around 78% of the air is nitrogen gas, and only 20.9% is oxygen.

Hope this helps.

answer: hang out with someone else or occupy your mind with something else. : )

the maintenance of fluid balance during exercise. author information: fluid supplementation is necessary for exercise in which fluid losses must be offset by intake to avoid the negative effects of hypohydration on health and performance.