What is the recommended surface interval after extended dives with Nitrox?

The recommended surface interval after extended dives with Nitrox is typically 120 minutes. This duration allows the body ample time to off-gas accumulated nitrogen safely, particularly after multiple dives or dives that have approached the limits of no-decompression time. Extended dives increase nitrogen absorption due to the higher partial pressures of nitrogen in the mixture, even though Nitrox has a lower nitrogen content compared to air. The 120-minute surface interval is also in alignment with guidelines to minimize the risk of decompression sickness and ensure a safe buffer before any follow-up dive.

While a longer surface interval could potentially provide an additional safety margin for off-gassing, it may not be necessary for every situation, making 120 minutes a reasonable recommendation for most extended dive scenarios. The physiological parameters taken into consideration include the individual diver’s exposure, the specific dive profile, and the mix used, which are critical in evaluating the appropriate surface interval.