What does residual nitrogen time relate to in diving?

Residual nitrogen time relates to the amount of nitrogen still present in a diver's body from previous dives, which affects ongoing dive planning. When a diver descends to a greater depth, nitrogen dissolves into the body tissues due to increased pressure. If a diver has recently completed a dive, some nitrogen remains in the body as the diver ascends to the surface. This residual nitrogen can influence how long and how deep the diver can safely dive in subsequent dives to avoid decompression sickness or "the bends."

Understanding residual nitrogen time is crucial for planning additional dives, ensuring the diver adheres to safe ascent rates and necessary surface intervals. Factors such as depth and duration of previous dives must be considered to determine the safe limits for further dives. This concept is integral to managing the risks associated with repetitive diving and maintaining diver safety.