How does the risk of oxygen toxicity change with increased partial pressure of oxygen?

As the partial pressure of oxygen increases, the risk of oxygen toxicity also increases. This relationship is critical in understanding how oxygen behaves under various pressures, especially in diving.

Oxygen toxicity primarily arises from the effects of increased oxygen levels on the central nervous system (CNS) and the pulmonary system. When a diver breathes a gas mix that has higher partial pressures of oxygen, such as enriched air (Nitrox), the concentration of oxygen in the blood and tissues elevates.

The CNS is particularly sensitive to increases in oxygen pressure, with toxicity risks escalating at partial pressures above 1.4 ATA (atmospheres absolute). Symptoms can range from visual and auditory disturbances to convulsions, which can pose serious risks during diving operations. Since the risks associated with oxygen toxicity grow alongside increased pressures, understanding this fundamental concept is essential for divers training with enriched air and in managing their dive profiles safely.

This knowledge is vital when determining the appropriate gas mix for specific diving conditions, ensuring that divers can minimize their exposure to potentially toxic levels of oxygen while maximizing their time underwater.