At a depth of 20 meters, what is the partial pressure of oxygen when diving with Nitrox 28?

To determine the partial pressure of oxygen when diving with Nitrox 28 (which contains 28% oxygen and 72% nitrogen), the relationship between depth, total pressure, and partial pressure needs to be understood. At a depth of 20 meters, the total pressure is typically calculated based on the formula:

Total Pressure (ATA) = Surface Pressure + (Depth in meters / 10).

At sea level, the surface pressure is approximately 1 ATA. Therefore, at 20 meters, the total pressure would be:

Total Pressure = 1 ATA + (20 meters / 10) = 1 ATA + 2 ATA = 3 ATA.

Since Nitrox 28 consists of 28% oxygen, the partial pressure of oxygen can be calculated using the formula:

Partial Pressure of Oxygen = Total Pressure x Fraction of Oxygen.

Using this, the calculation would be:

Partial Pressure of Oxygen = 3 ATA x 0.28 = 0.84 ATA.

This calculation shows that at a depth of 20 meters while breathing Nitrox 28, the partial pressure of oxygen is indeed 0.84 ATA, making this the correct answer. Understanding this concept is essential for safe diving practices, as it helps divers manage their