What does the term "partial pressure of oxygen" (PO2) refer to?

The term "partial pressure of oxygen" (PO2) specifically refers to the pressure exerted by oxygen in a mixture of gases. It is an important concept in diving, particularly when using gases like nitrox, where the amount of oxygen in the gas mixture affects both the diver's physiology and the potential for oxygen toxicity.

In a gas mixture, each gas contributes to the overall pressure in proportion to its amount, and the partial pressure indicates the individual contribution of each gas. For divers, understanding the PO2 is crucial for managing exposure to oxygen at various depths, as higher pressures can increase the risks related to oxygen toxicity. This understanding helps divers plan their dives to remain within safe limits, particularly when using enriched air nitrox, which has a higher percentage of oxygen compared to regular air.

By accurately determining the partial pressure, divers can assess their risks and make informed decisions regarding their dive profiles and safety measures.