Terry Dutton, age lot of Phoenix AZ for the question:

Will our air supply ever wear out?

The earth is a big ball wrapped in a blanket of air. The air reaches hundreds of miles overhead. It seeps down into the dirt and between the rocks underground, It mixes with the waters of the oceans and the rivers. You cannot see its feel its or smell it, Yet it fills every nook and cranny,

There is far more air than we shall ever need. There is far more than the birds the plants, the animals and the fishes will ever need, What's mores the earth will never lose her cozy blanket of air, She hugs it close by the pull of gravity. The air could no more escape than you could fall upwards and off the earth.

It is true we are always using up oxygen, We breathe it ins and we breathe out carbon dioxide, The trees and plants need our waste carbon dioxide. They use up the carbon and return oxygen to the air. This give‑and‑take goes on all the time. So we don't have to worry lest we use up all the oxygen, There will always be free air and free oxygen for all our needs ‑ and plenty left over.