Which gas law is applied for determining PPO2?

The determination of partial pressure of oxygen (PPO2) in gas mixtures is primarily based on Dalton's law, which states that in a mixture of non-reacting gases, the total pressure is equal to the sum of the partial pressures of each individual gas.

This law is particularly relevant in diving scenarios where multiple gases may be present in a mix, such as air or other breathing gases. By knowing the total pressure at a given depth and the fraction of oxygen in that gas mix, one can apply Dalton's law to calculate the PPO2. For instance, if you are at a depth where the pressure is 3 atmospheres and the gas mixture consists of 21% oxygen (like regular air), you can calculate PPO2 as:

PPO2 = Total Pressure x Fraction of Oxygen = 3 atm x 0.21 = 0.63 atm.

Understanding this relationship is crucial for divers, as it allows them to make informed decisions regarding their breathing gas recipes, ensuring safe and effective diving operations.