Air vs Nitrox vs Trimix – Comparing the Gasses

Here’s a breakdown of three of the more well-known breathing gas mixtures available to divers, today. As you can see, there are different mixtures for different conditions, and the science behind which breathing gas you should use is thorough and precise so that you can stay safe and have a great dive.

Air

Atmospheric air is the most commonly used gas for recreational scuba diving. It is generally a mixture of nitrogen and oxygen, with some trace amounts of carbon dioxide, argon, and other gases. In terms of percentages, most standard air contains about 78% nitrogen and 21% oxygen, and the air in a scuba tank has been compressed for longer usage under the water.

This breathing gas is considered safe on dives of less than 40 meters (130 feet) and requires no special equipment other than your tank and breathing apparatus, which makes it perfect for most recreational divers. If you’re not interested in going deeper than that, you can be content with having air in your tank, and you’ll only have to worry about the most basic diving certifications.

Nitrox

Nitrox, like atmospheric air, contains a mixture of nitrogen and oxygen, but the percentages have been adjusted to reduce the risk of decompression illness and allow divers to stay underwater longer (although not deeper) safely.

Most Nitrox is made up of a blend to lower nitrogen and incerase oxygen (although recreational dives can also include oxygen levels of as low as 22%). This higher oxygen content reduces the risk of getting the Bends because it decreases the amount of nitrogen being absorbed into the tissues. Of course, there are also risks for breathing higher levels of oxygen, which means that Nitrox has depth limits and it is not safe diving at greater depths.

Nitrox or Air or even Trimix - Which is best

In order to use Nitrox safely, it’s important to get special training on the topic. In terms of special equipment, you’re going to check the accuracy of your blend. You can use the shops analyzer or purchase your own. There is also a risk of flammability whenever you’re dealing with pure oxygen, so tanks must be cleaned for use with Nitrox and serviced annually.

Trimix

In many ways, Trimix is in a league of its own when it comes to breathing gases. This blend, is made up of helium, oxygen, and nitrogen.

The use of helium allows divers to explore depths that would be unsafe with other breathing gases because of the risk of narcosis and oxygen toxicity. While the exact percentage of each element depends on the depth of the dive, trimix blends for a dive of 240 feet may consist of 17% oxygen, 33% nitrogen, and 50% helium.

Trimix is largely outside of the scope of recreational diving practices because it requires extensive training and equipment. That’s not to mention the logistical adjustments you also need to consider for dives using Trimix

Should you consider diving with Nitrox or even Trimix

It all depends on where you see your diving career, long-term. If you enjoy shorter dives in which you can explore shallow depths, you don’t need to pursue anything more than atmospheric air.

However, if you are interested in stepping up your game or becoming a technical diver, you may want to look into getting certified in more complex breathing gas usage.

Whatever you decide, make sure that you’re putting careful thought into what is in your breathing gas.