In the context of diving, what does nitrogen build-up refer to?

Nitrogen build-up in the context of diving specifically refers to the absorption of nitrogen into the body during dives. When a diver descends, the increased pressure leads to a greater amount of nitrogen from the breathing gas being dissolved in the body's tissues and the bloodstream. This dissolved nitrogen is harmless at depths, but as the diver ascends, the pressure decreases, causing the nitrogen to come out of solution. If ascents are too rapid, the nitrogen may form bubbles in the tissues and bloodstream, leading to decompression sickness, commonly known as "the bends."

Understanding this physiological process is essential for divers to avoid these risks, which is why nitrogen build-up is such a crucial concept in dive physics and safety practices.