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Equivalent Air Depth (EAD)

Description

The Equivalent Air Depth (EAD) is a calculation for divers using nitrogen-oxygen (NITROX) breathing gas mixtures. It refers to the depth at which the same partial pressure of nitrogen is achieved as when using a regular air breathing mixture. The partial pressure of nitrogen is an important factor for the diver's risk of decompression sickness.


 

decimal fraction of nitrogen in the gas mixture =

= (1.0 – (decimal fraction of oxygen))

 

For normal air, the decimal fraction of nitrogen is 1.0 – 0.21, or 0.79. For NITROX mixtures range from 75% nitrogen and 25% oxygen to 60% nitrogen and 40% oxygen.

 

equivalent air depth in feet of salt water =

= ((1.0 – (decimal fraction of oxygen)) * ((depth in feet diving with NITROX mixture) + 33) / 0.79) – 33

 

The equivalent air depth using a NITROX air mixture is typically shallower than the diver's actual depth. This means that:

(1) a diver can increase the amount of time at depth without decompression.

(2) the decompression time is less than that for a similar dive made to the same depth using air.

 


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Specialty

ICD-10