Waiting to Exhale

By Sophia Read
For The Bali Times

SEMINYAK ~ In general in life, particularly in the Western world, we are looking for the quick fix, the biggest, best and quickest bang for our buck – a life of soundbites. But there are times when we want to step off the merry-go-round for a while (a move to Bali, for example, provides a slower pace of life than any Western city).

Diving is a way to unwind … take things more slowly … see a different side to the world.

That said, one thing that frustrates divers is the limited time they can spend underwater on each dive.

One reason is the effect of nitrogen in the body. The greater the depth, the more nitrogen is absorbed into your blood; then (due to the decreasing water pressure) as you ascend, the absorbed nitrogen expands. This means if your body has absorbed too much nitrogen or you ascend too quickly for the nitrogen to reach your lungs and get breathed out, the nitrogen bubbles can become stuck, most typically in your joints. This is known as DCS (decompression sickness) or “the bends” and means a trip to the nearest recompression chamber – in Bali it’s at Sanglah Hospital, and is very expensive outside office hours.

Recreational diving is called no-decompression diving, meaning a diver can theoretically ascend directly from their maximum depth to the surface without having to do decompression stops. It’s always advisable, though, to do a 5 meters for 3 minutes safety stop after every dive.

Prior to diving, divers calculate the amount of time they can spend underwater based on no-decompression limits – the time it takes the body to offgas all or some of the nitrogen absorbed. Dive computers (like large watches) simply calculate these limits, based on the same algorithms as dive tables. If the correct limits are observed, there is minimal risk of DCS in a healthy diver.

But these limits are restrictive, and there’s nothing more irritating than to have to cut short an amazing dive (watching a group of Manta fly gently round and round you, perhaps drifting along next to a giant Mola-Mola) because it’s time to go to the surface.

There is a solution – nitrox.

Nitrox divers can spend longer underwater and need to spend less time on the surface between each dive. Nitrox simply means a mixture of nitrogen and oxygen. Normal air is nitrox, too – 78 percent nitrogen, 21 percent oxygen and 1 percent other gases. The nitrox referred to by divers is simply a mixture of these gases with less nitrogen, and more oxygen (not, as the name seems to imply, more nitrogen). It’s also referred to, less confusingly, as Enriched Air Nitrox, or EAN. For recreational divers, the normal percentage of oxygen included in the mix is either 32 percent or 36 percent.

Breathing nitrox decreases the nitrogen inhaled by the diver, and so allows the diver to spend longer underwater, while allowing the body to still offgas the same amount of nitrogen. So, for example, a diver breathing normal air may stay underwater for 80 minutes without going into decompression time, but a diver breathing nitrox 32 percent can stay for 200 minutes.

Myths about nitrox are common, and one of the most pernicious is that it allows you to dive deeper. The reverse is true. Nitrox divers are limited to shallower depths than people breathing normal air, because of the risks of Oxygen Toxicity. (Breathing too high a concentration of oxygen damages cells, but the body, or rather the brain, has no mechanism for measuring the amount of oxygen being inhaled, so the diver will experience no warning signs.)

The percentage of oxygen in the mix determines the depths to which a diver can go while breathing nitrox. Nitrox 32 percent has a maximum operating depth of 34 meters, and nitrox 36 percent only 29 meters.

To breathe nitrox when diving, it is essential that divers are first properly trained – most reputable dive centers in Bali run PADI Nitrox courses. The course teaches you everything you need to know about how to ensure that the gas mixture is correct, and how to calculate your new time limits.

Equipped with nitrox, the underwater world truly becomes your playground, and your understanding and appreciation of its complexity and beauty grows with every extra minute.

The writer is sales manager for AquaMarine Diving – Bali.

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