What is the primary mechanism by which divers can reduce the risk of decompression sickness (DCS)?

Controlled ascent rates are essential in reducing the risk of decompression sickness (DCS) during diving. As divers descend deeper, the pressure increases, causing inert gases like nitrogen to dissolve into the body’s tissues. If a diver ascends too quickly, these gases can form bubbles in the tissues and bloodstream, leading to DCS. By ascending slowly and in a controlled manner, divers allow their bodies ample time to safely off-gas nitrogen and other inert gases. This process is typically supported by following dive tables or a dive computer that provides specific guidelines for safe ascent rates and safety stops, which further help mitigate DCS risk.

The other options do not effectively reduce the risk of DCS. Immediate surface ascent can actually increase the risk of DCS because it does not allow the nitrogen to off-gas safely. Extended bottom time can lead to greater absorption of nitrogen, increasing the risk if the ascent is not managed properly. While supplemental oxygen can be beneficial for certain conditions and scenarios post-dive, it is not a fundamental mechanism for preventing DCS during the ascent. Thus, adhering to controlled ascent rates is the most practical and effective method for divers to minimize the risk of decompression sickness.