An hour after surfacing from a deep dive, a diver experiences fatigue and shoulder numbness. What is a potential concern?

The symptoms of fatigue and shoulder numbness occurring an hour after surfacing from a deep dive suggest a possible case of decompression illness. Decompression illness, commonly known as "the bends," can occur when a diver ascends too quickly or does not follow proper decompression procedures after being subjected to high pressures underwater.

During deep dives, nitrogen is absorbed into the body's tissues under pressure. If a diver ascends too rapidly, the nitrogen can form bubbles in the bloodstream, leading to a range of symptoms, including fatigue, numbness, joint pain, or even more serious complications. The timing of the symptoms also aligns with how decompression sickness can present itself, often occurring within hours of surfacing.

Other options, while possible concerns in different contexts, do not directly relate to the specific symptoms described. Equipment weight can lead to fatigue but generally doesn't cause numbness. Contaminated air poisoning would likely present with additional respiratory symptoms, and overexertion is less likely to cause numbness without significant strain or injury. Thus, decompression illness is the most relevant concern given the diver’s recent deep dive history and the nature of the symptoms experienced.