Which gas is most essential for human respiration?

Oxygen is the most essential gas for human respiration because it plays a critical role in the process of cellular respiration, which is how our bodies generate energy. During this process, cells use oxygen to help convert glucose from food into ATP (adenosine triphosphate), the primary energy currency of cells. This reaction releases carbon dioxide and water as by-products.

While nitrogen makes up a significant portion of the air we breathe, it is mostly an inert gas and does not participate actively in the respiratory process. Carbon dioxide is produced as a waste product of metabolism and is important for regulating blood pH, but it is not consumed in respiratory processes in the same way oxygen is. Argon is also an inert gas found in the atmosphere and has no role in human respiration. Thus, oxygen is vital for sustaining life by enabling the biochemical processes that supply energy to our cells and organs.