How does increased O2 concentration affect dive planning?

Increased oxygen concentration in diving mixtures, such as those used in enriched air nitrox, directly impacts the maximum operating depth of a dive due to the risk of oxygen toxicity. As the percentage of oxygen in the mix increases, so does the partial pressure of oxygen that a diver experiences at depth.

Oxygen toxicity can result in various neurological and pulmonary effects, which become more pronounced as the partial pressure exceeds safe limits. For recreational diving, the generally accepted maximum partial pressure for oxygen is 1.4 ATA (atmospheres absolute) to minimize the risk of toxicity. This limit in turn restricts how deep a diver can go when using a higher concentration of oxygen, hence necessitating lower maximum operating depths.

Understanding this relation is crucial for dive planning, as divers must carefully calculate their depth limits to ensure safety while utilizing enriched air nitrox.