How does altitude affect dive planning?

Altitude can significantly impact dive planning, particularly concerning the risk of decompression sickness (DCS). As a diver ascends to higher altitudes, the atmospheric pressure decreases. Since diving involves breathing compressed air, this reduction in pressure can alter the behavior of dissolved gases in the body, particularly nitrogen.

Under these conditions, the risk of decompression sickness increases because the body may hold onto more nitrogen when exposed to lower pressures compared to sea level. If a diver who is at altitude performs a dive and later ascends to an even higher altitude (like returning to a high-altitude location), the decreased ambient pressure can lead to the formation of nitrogen bubbles in the body, which can cause DCS.

Proper dive planning at altitude must account for these factors, ensuring that divers are aware of the additional risks. This includes adhering to modified dive tables or using dive computers that adjust for altitude, allowing divers to safely manage their exposure to nitrogen without exceeding safe limits and minimizing the risk of injury.