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Nitrox: What You Need To Know About This Gas

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If you’ve spent any time diving recreationally, you’ve probably noticed tanks of nitrox in your dive shops and may be wondering what it is, how it works, and how it’s used.

Let’s discuss nitrox and how it can benefit many divers.  

What is Nitrox?

vector graphic showing three nitrox tanks on a dock by the water

Nitrox is a specialty blend of oxygen-enriched air.

Normal atmospheric air has about 21% oxygen and 78% nitrogen, with 1% other gases.

Nitrox usually contains 32% oxygen and 68% nitrogen but can also come in different concentrations and levels.

The maximum concentration of oxygen in tanks for recreational divers is 40%.

Regardless of the specific blend, nitrox always refers to air tanks with a higher amount of oxygen and less nitrogen than atmospheric air, which is why it’s also called ‘enriched’ or ‘oxygen enriched’ air.

How is Nitrox Used in Scuba Diving?

To put it simply, the reduced amount of nitrogen in nitrox reduces the amount of nitrogen available to dissolve in your bloodstream in the higher pressure underwater environment.

Therefore, when used the right way, nitrox reduces a diver’s chances of getting the bends or suffering from decompression sickness. 

In addition, nitrox extends no-decompression dive times, allowing divers to dive for longer times with fewer decompression stops and risk of the bends.

What are the Risks of Diving with Nitrox?

The primary risk when diving with nitrox is the chance of oxygen toxicity.

Oxygen can become toxic at high concentrations, and the risk increases under greater pressure.

For divers using atmospheric air, the risk of oxygen toxicity is very low above depths of about 220 feet.

However, when using oxygen-enriched air, the risk of oxygen toxicity is higher on standard recreational depths.

Oxygen toxicity can cause cell damage, seizures, problems with the central nervous system, affect the eyes and vision, and affect the heart and lungs.

When diving with nitrox, it is critical to calculate your oxygen limit by multiplying your oxygen percentage and the atmospheres of pressure at your planned dive depth.

The basic rule is that using nitrox does not allow you to dive deeper; it will enable you to dive longer.


When Should You Dive with Nitrox?

Nitrox is especially beneficial in specific recreational diving scenarios.

The best times to use nitrox are dives between 50-100 feet.

For dives at this depth, nitrox can significantly:

Extend Your Dive Time

A 36% blend of nitrox can double your dive time at depths of 100 feet, from 20 minutes to 40 minutes.

At 60 feet, a 36% blend can give you 130 minutes of dive time instead of 50.

Having a longer no-decompression dive time allows you to spend more time diving and less time ascending. 

Reduce the Risk of Decompression Sickness

At these depths, divers using nitrox enjoy no-decompression dive limits for longer and can also enjoy more dives in a shorter period with less rest in between.

For Medical Reasons

Some divers have a higher risk of decompression sickness or have physical reasons why nitrox is a better choice.

For example, older divers, divers recovering from injury, or less physically fit may benefit from diving with nitrox.

In other dive conditions and situations, nitrox should be used with added caution, if at all.

How Much Nitrox Should I Use?

The most important thing to do when considering diving with nitrox is to get nitrox certification.

Nitrox/enriched air certification is an incredibly popular certification because many recreational divers want to know how to extend their dive times.

A typical nitrox/enriched air course will include:

  • Understanding and managing the risks of oxygen toxicity
  • Dive planning with air depth and oxygen exposure tables
  • Using a dive computer to calculate dives based on oxygen concentrations and atmospheres of pressure

A nitrox certificate will help you determine the correct nitrox blend for your depths and dive times and help you understand how nitrox affects your dive plan.

The certification allows you to use enriched air tanks when on vacation or in unfamiliar dive shops.

Wrapping Up

Oxygen enriched air can be a great way to allow recreational divers to dive for longer, with reduced need for decompression stops and reduced risk of decompression sickness.

It is not the right choice for every diver or every dive but can make many recreational dives more enjoyable.

Nitrox certification is a great way to learn how enriched air can enhance your dives while understanding the risk and the proper use of oxygen-enriched air; it also helps you be a more informed diver and better dive planner.

It’s well worth taking the course, even if nitrox isn’t always the right choice for a specific dive.

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