On May 16th a third Russian diver lost his life as well diving on air to 285 meters.
Do any of you old timers like myself remember the ‘Deer Hunter’? It is a classic 70’s film staring Robert De Niro with the famous Russian roulette scene: A pistol chamber is emptied save for one single bullet, the character then puts the gun to his head after rotating the chamber and pulls the trigger not knowing if he will draw a blank or get the single bullet and die.

The point is, if you keep pulling the trigger your luck will eventually run out and you will get the bullet in your head. So, what does this have to do with diving?

Deep air diving is really not any different from Russian roulette. It is dangerous, completely irresponsible and if you do it often enough you will ultimately die.

WHAT IS DEEP? Before we go into the inherent dangers of deep air diving, we shall try and put into perspective the concept of deep.

On a conceptual level and not withstanding the actual depth as expressed in MSW - (meters of sea water), one would break up the depth range of any dive into the following zones:

The Comfort Zone:
This is the range where the diver is relaxed, enjoying the dive and in total control of himself and his equipment and fully aware and comfortable with his/her environment and surroundings.

The Thrill Zone:
This is where the diver leaves his/her comfort zone and pushes further for a new experience and bit of excitement while still in control and in focus on what he/she is doing and what is happening around them.

The Stress / Panic Zone:
When a diver goes way beyond his/her comfort zone and thrill zone and into a situation where stress starts to build up. Stress, if left unchecked would quickly develop into PANIC (acknowledged to be a leading factor in fatal diving accidents).
This is the zone that we want to avoid at all times.
The message here is that beginners and inexperienced divers should always stay within their comfort zone until they develop enough experience and self confidence to move slowly into the thrill zone.

Deep Air Diving is a killer – sooner or later:
The analogy between deep air diving and Russian roulette as stated earlier is that both will eventually kill you.
So, what are the hazards of deep air diving and why can they become lethal? As all divers know, air is essentially made up of two gases, 21% oxygen (O2) and 79% nitrogen (N2).
Each of these two gases under elevated pressure or in other words the elevated partial pressure of each of the two gases independantly or together can cause a fatal accident.
Partial pressure is a direct result of increased depth, so let us consider what happens at depth while breathing compressed air.

Nitrogen Narcosis:
(the ‘Martini’ effect)
Simply put the deeper you go on air, the higher the nitrogen partial pressure, and the more you start losing your concentration, orientation and ability to think or see clearly and at the extreme would lead to loss of consciousness (this means death when you are underwater).

O2 Toxicity:
(the dark prince of gases)
Oxygen is the gas that gives us life and sustains all living things, yet if you do not treat it with respect it will kill you.
Not many beginners are fully aware of the ugly face of oxygen. Simply put, an elevated oxygen partial pressure (PPO2) could lead to oxygen toxicity which means that the diver could convulse underwater leading to almost certain death.

The absolute maximum oxygen partial pressure allowed by all technical dive training agencies for the qualified and well trained technical divers is a PPO2 of 1.6 ATA, which for technical air dives means a depth of 66 MSW.

(1.6 ATA / .21 = 7.6 ATA = 66 MSW)

Having said that, the recommended PPO2 limit is 1.4 ATA, ie 56 MSW.

The reason 1.6 is set as absolute maximum is simple; all empirical tests conducted by NOAA on oxygen toxicity showed that at partial pressures of less than 1.6 ATA (PPO2) hardly any cases of O2 toxicity were recorded.

Gas Consumption Considerations:
Another hazard of deep diving which is quite obvious but often overlooked is running out of gas at depth.

How many divers actually know what their RMV ( Respiratory Minute Volume ) or SAC (Surface Air Consumption) rate is?

The time an average recreational diver will have when diving to 60 metres on a 12 liter cylinder pumped to 200 bar is only 17 minutes, (assuming the average consumption rate of 20 lit/min at the surface).