Which statement about cold water and decompression stress is true?

• A. Cold water decreases decompression stress
• B. Cold water has no effect on decompression stress
• C. Cold water slightly reduces decompression risk
• D. Cold water increases decompression stress

Answer: (D)

Cold water raises decompression stress because cooler conditions change how nitrogen behaves in the body. Lower water and tissue temperatures increase nitrogen solubility, so more nitrogen dissolves into tissues during the dive. At the same time, cold-induced peripheral vasoconstriction reduces blood flow to the extremities, slowing the removal of that dissolved gas. When you ascend and pressure drops, the stored nitrogen has a greater tendency to come out of solution as bubbles, increasing the risk of decompression sickness. The added physiological strain of cold exposure, like shivering, can further contribute to overall stress on the body during ascent. So cold water actually raises, not lowers, decompression stress.