What is the atmospheric pressure at the surface plus 33 feet of sea water?

To understand why the atmospheric pressure at the surface plus an additional 33 feet of sea water is represented as 2 atmospheres absolute, it’s essential to grasp the relationship between water depth and pressure.

At sea level, the atmospheric pressure is approximately 1 atmosphere (atm). As you descend in water, the pressure increases due to the weight of the water above you. The general rule of thumb is that for every 33 feet of freshwater (or for seawater, roughly similar), the pressure increases by about 1 atmosphere.

Thus, when you are at the surface, you start with 1 atmosphere. As you go down 33 feet in seawater, you gain another atmosphere due to the water’s weight, resulting in a total pressure of 2 atmospheres absolute at that depth. It's crucial to recognize that the total pressure is the sum of the atmospheric pressure at the surface plus the additional pressure exerted by the water column.

This understanding links directly to principles of physiology, diving, and atmospheric science, which are integral to flight paramedic training, particularly in understanding how pressure changes affect the human body and equipment in flight situations.