What happens to the total pressure of inspired gas as a diver descends?

• A. It decreases
• B. It remains constant
• C. It increases
• D. It fluctuates

Answer: (C)

As a diver descends, the total pressure of the inspired gas increases due to the added weight of the water column above the diver. The pressure exerted by the atmosphere and the column of water combined creates a higher total pressure as the diver goes deeper. For every 10 meters of seawater, the pressure increases by approximately one atmosphere (atm), which is about 14.7 psi. Therefore, at depths of 10 meters, 20 meters, and so forth, the total pressure increases significantly. This principle is fundamental to understanding diving physiology and the behavior of gases under pressure, which is critical for safe diving practices and preventing conditions such as barotrauma and decompression sickness.