Which medical gas supports combustion and must be handled with caution?

Oxygen is the medical gas that supports combustion and requires careful handling due to its highly reactive nature. When in the presence of a combustion source, oxygen can greatly enhance the intensity and speed of a fire. This is particularly important in medical settings, where oxygen is often used to support patients' respiratory needs.

In environments where oxygen is present, flammable materials can ignite more easily and burn with greater ferocity than in ambient air. Therefore, it is crucial to maintain stringent safety protocols, such as keeping oxygen tanks away from heat sources and ensuring that all equipment used in conjunction with oxygen is free from flammable contaminants.

The other gases listed, like carbon dioxide, nitrogen, and helium, do not support combustion in the same way. Carbon dioxide is used as an extinguishing agent in fire suppression, nitrogen is an inert gas that does not behave reactively, and helium is similarly non-flammable. This distinction underscores the necessity of caution when working with oxygen in any medical or clinical setting.