What gas is the main trigger that makes you want to breathe?

The primary driver for the urge to breathe is carbon dioxide. As it builds up in the bloodstream during respiration, it creates a condition known as hypercapnia. High levels of carbon dioxide result in increased acidity of the blood, which is detected by chemoreceptors in the brain and other areas of the body. These receptors send signals to the respiratory center in the brainstem, prompting an increase in the rate and depth of breathing to expel excess carbon dioxide and restore balance.

While oxygen levels do play a role in respiration, they are not the primary trigger for the breathing reflex. Our bodies can tolerate a wide range of oxygen saturation levels for some time, whereas elevated carbon dioxide levels prompt an immediate and strong physiological response aimed at re-establishing normal respiratory function.

Understanding this mechanism emphasizes the importance of monitoring carbon dioxide levels in diving situations, as elevated levels can have serious implications for diver safety and well-being.