Do we really need an 02 kit when we dive?

By Gemma Smith

Every new diver learns in “Scuba 101” about the benefits of breathing pure oxygen. It reduces the severity of specific diving-related medical conditions, such as decompression sickness (DCS) and arterial gas embolism (AGE). Breathing pure oxygen at the correct flow rate allows faster off-gassing of nitrogen. This is the excess nitrogen that our tissues have absorbed and on-gassed during our dives. Oxygen is also known to improve the body’s circulation. This helps the faster re-oxygenation of our tissues.

Any reputable boat you dive from will undoubtedly have oxygen on board. This is also true of commercially run dive sites you may visit. Divers who shore dive away from a dive center, or who dive off the beaten track, should consider carrying oxygen with them then. Taking oxygen with you, or having access to an O2 kit, should be seen as standard. No different than making sure you take your regulator, BCD, mask, fins, and dive computer with you. It is surprising then how many divers don’t add an oxygen kit to their “must have on every dive” checklist. So let’s look a bit more at why carrying oxygen with you is so important to us as divers, as well as the history and logistics of having access to this crucial gas.

So when was oxygen first used to treat diving related maladies then?

Decompression illness in its various forms has been noted and remarked upon for many centuries. This was despite the mechanism behind the signs and symptoms not being fully understood at the time. Several key figures have had an impact on recognising the benefits of oxygen to treat these symptoms.

Perhaps the most obvious example is that of the French physiologist Paul Bert. As far back as the mid to late 1800s, he was using 100% pure oxygen to treat caisson workers. They were exhibiting what we now know to be the signs of DCS. Despite the success Paul Bert encountered with this method, it would be many more years before its use became widespread.

This practise of giving sufferers of DCS surface-pressure oxygen has now evolved to the standard treatment of using hyperbaric oxygen for dive injuries. It is also worth noting that oxygen has many and varied medical uses beyond just diving related emergencies.

I never dive deep though, so surely I won’t ever suffer from DCS?

While DCS is perhaps more common on deep, long, or cold dives, it is in no way restricted to these environments. Working hard at depth, being physically unfit or excessively dehydrated, or ascending beyond a safe, slow rate can also produce symptoms. The effects can also on occasion appear randomly. Even on simple dives while following all proper dive practices, DCS may occur.

As such, a good diver knows how important it is to always be ready with the correct gear and correct training to limit possible accidents. This is far better than trying to deal with potentially worse results because of lack of adequate preparation. Making sure you have access to a properly maintained O2 kit is one way of looking after yourself, and your buddies.

So what do I look for in an Oxygen kit?

Different regions have different regulations governing requirements for oxygen kits. Take the time to do your research, and make sure you are acquiring a suitable system. All oxygen kits consist of three separate parts: the actual cylinder, the first stage regulator attaching to the cylinder, and a delivery device that the patient breathes from.

The cylinder itself is usually either steel or aluminium. Aluminium cylinders are much more commonly seen though. It is also very important that the cylinder valve is rated and cleaned for use with high-pressure oxygen. The regulator is a simple device which reduces the high-pressure gas in the cylinder to ambient pressure. While it is similar to a scuba regulator, it is not for underwater use. Dryland only!

As for the actual method for delivering oxygen to the diver, there are various options. The two most commonly used systems are the demand and the constant flow system. While both types work, a constant flow system is usually the preference.

Storage and Maintenance

The storage of emergency oxygen kits should always be according to manufacturers instructions. Local and federal rules will also impact the use, transport, and maintenance of pressurised oxygen kits. As a general rule though, there are some basic guidelines to follow:

  • Always make sure the system is in a shockproof and waterproof case. Make sure when transporting an oxygen kit it is securely fixed to prevent rolling or impact damage.
  • Remember your laws of physics, and never leave any kind of cylinder in a hot car. This has all kinds of possible safety issues with gas expansion due to heat.
  • Avoid exposing oxygen kits to contaminants. Ensure it is always free from dirt, grease, and oil.
  • Keep track of the required dates of service of both the cylinder and the regulator. Cylinders typically need a hydrostatic test every five years, and the regulators every two. Always check local rules and regulations, as well as manufacturers guidelines, on this point though.


Having your own oxygen kit is not mandatory if you have easy access to an oxygen system when and where you dive. It is, however, prudent to consider unlimited access to one if you often dive in remote locations. Assess your situation and act accordingly.

It is also important to remember that if a diver has been given oxygen for a possible DCS or AGE incident they need to go to a local hospital or equivalent. This is crucial even if signs and symptoms appear to have lessened. It is important to receive the all-clear from professional medical personnel. After all, keeping our minds and bodies healthy means more time for diving!

Want to learn more about administering O2? Check out our O2 Administration course here.

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