What is the partial pressure of nitrogen in air at 132 feet of salt water?

To determine the partial pressure of nitrogen in air at a specific depth, we need to understand the relationship between depth, pressure, and gas composition in air. At sea level, the atmospheric pressure is approximately 1 atmosphere (atm), and air is made up of about 78% nitrogen.

When diving, pressure increases with depth. For every 33 feet of salt water, the pressure increases by about 1 atm due to the water above. At 132 feet, you would experience a total pressure of approximately 4 atm (1 atm for surface pressure and 3 atm for the depth).

The partial pressure of nitrogen can be calculated using the formula:

Partial pressure of nitrogen (ppN2) = Total pressure (atm) × Fraction of nitrogen in air.

Using the known fraction of nitrogen in air (0.78), the calculation at 132 feet would be:

Total pressure = 4 atm (atmospheric pressure at 132 feet)

ppN2 = 4 atm × 0.78 = 3.12 atm

Now, converting this value into partial pressure of nitrogen in units of partial pressure for practical diving calculations, we typically express ppN2 in units that reflect the depth-specific pressures. At 132