How does air help people?

Answer 1

Air contains the oxygen that people and animals need to live. Air is about 78% nitrogen and 20% oxygen, and our lungs remove that oxygen to operate the metabolic activities of our bodies. In living cells, oxygen combines with carbohydrates (oxidizes them) to create energy for the cells. Where the air is thinner (less dense), at higher altitudes such as mountaintops, there is less oxygen by volume, so the lungs have to process more air.

Where oxygen has been removed, or replaced by other gases (such as carbon dioxide or darbon monoxide), we cannot get enough oxygen. This can occur in a small room with many people, or where a fire uses up the oxygen. A fire in an enclosed space uses up the oxygen and puts carbon dioxide and carbon monoxide in its place. This makes the air dangerous to breathe.