During ascent, decompression stops are used to...

• A. Increase bottom time
• B. Improve air efficiency
• C. Allow safe elimination of inert gases
• D. Shorten surface interval

Answer: (C)

Decompression stops are used to allow safe elimination of inert gases from the body as you ascend. At depth, nitrogen dissolves into tissues under pressure; as you rise, the surrounding pressure drops, and those dissolved gases become supersaturated. If you ascend too quickly, bubbles can form in tissues and cause decompression sickness. By pausing at specific depths for planned durations, your body has time to diffuse nitrogen from tissues into the blood and be expelled through the lungs, keeping tissue pressures within safe limits. These stops don’t increase bottom time or directly improve air efficiency; they are a controlled part of the ascent that reduces the risk of bubble formation. They also lengthen the overall ascent and, consequently, affect surface interval planning.