What would happen if oxygen were not available

We wouldn't be able to breathe as we are no longer taking in oxygen and we would die.

we breathe in oxygen and breathe out carbon dioxide.

No oxygen would be taken in, so less carbon dioxide is also breathed out.

Answer: we would die

Explanation:

Brain cells are very sensitive to a lack of oxygen. Some brain cells start dying less than 5 minutes after their oxygen supply disappears. As a result, brain hypoxia can rapidly cause severe brain damage or death.