Why are safety stops recommended during ascent?

Safety stops are recommended during ascent primarily to off-gas nitrogen and reduce the risk of decompression sickness. As divers descend, their bodies absorb more nitrogen due to the increased pressure. When ascending, if a diver does not allow sufficient time for the nitrogen to safely exit their body, it can form bubbles in the tissues or bloodstream, which may lead to decompression illness. By conducting a safety stop, typically at a depth of 3 to 5 meters (10 to 15 feet) for a few minutes, divers facilitate the release of this excess nitrogen in a controlled manner, significantly lowering the likelihood of developing decompression sickness.

This practice is rooted in understanding the physiological effects of nitrogen under pressure and is an essential part of dive safety protocols. It allows the body to adjust to the changing pressure instead of experiencing a rapid ascent. The other choices do not address the primary purpose of safety stops; for example, while equalizing pressure in the ears is crucial during descent, it is not relevant to the need for safety stops during ascent. Similarly, preventing equipment damage and saving air in the tank are important considerations in diving, but they do not directly relate to the physiological need to manage nitrogen levels in the body as divers ascend.