Why is it crucial for divers to breathe pressurized air?

Breathing pressurized air is crucial for divers primarily because the surrounding water pressure increases significantly as they descend into deeper waters. At greater depths, the pressure can be much higher than at the surface, and this high pressure affects the volume of air in the lungs. If divers were to breathe unpressurized air at these depths, their lungs would not be able to expand properly, which could lead to serious complications such as lung barotrauma.

To counteract the effects of increased pressure, divers use pressurized air, which allows them to maintain normal lung expansion and contraction. This is essential not only for comfort but also for maintaining proper gas exchange—ensuring that oxygen can be absorbed into the bloodstream while carbon dioxide is expelled.

The other options do not adequately address the physics of pressure and human physiology under water, making them less relevant in this context. For instance, carbon monoxide poisoning is unrelated to the pressure conditions divers experience, and while respiratory infections can occur, they are not caused by pressure changes underwater. Increased oxygen intake would not solely be a function of breathing pressurized air because that also involves the composition of the breathing gas used in diving.