What gas is essential for human life?

The gas that is essential for human life is oxygen (O2). Oxygen is a colorless, odorless, and tasteless gas that makes up about 21% of the Earth's atmosphere. It is essential for the respiration process, which is how the body converts food into energy. Oxygen is transported to the cells by the bloodstream, where it is used to produce adenosine triphosphate (ATP), the energy currency of the cell. Without oxygen, the cells would not be able to produce ATP and the body would not be able to function.