This is a question I have been asked many times as a PADI Instructor. In this blog I hope to help you understand what exactly Nitrox (or Enriched Air Nitrox) is, and how it can benefit your diving.
The normal air we breathe (as well as the air inside of a normal scuba diving cylinder) is made up of approximately 21% oxygen and 79% nitrogen.
As we go underwater, increased pressure causes us to absorb nitrogen into our blood stream, the deeper we go, the more nitrogen we absorb. As we come to the surface, we slowly release the nitrogen we have absorbed. Our bodies can only absorb a certain amount of Nitrogen, if we absorb too much, we run the risk of decompression sickness if we had to ascend in the event of an emergency
As divers, we know that these limits have been created especially for us, and are called our “no decompression limits.” This simply means that we can stay at that particular depth within those time limits and come safely to the surface with little risk of decompression sickness.
What is Nitrox?
Nitrox very simply refers to a combination of nitrogen and oxygen. When we refer to Nitrox with regard to diving, we are usually referring to Enriched Air Nitrox, which means that we have added more oxygen to the compressed air inside the cylinder than the standard 21% found in air.
How does Nitrox benefit diving?
Well very simply, the more oxygen we breathe, the less nitrogen we absorb. So if we are diving with a higher percentage of oxygen it will take us longer to reach the no decompression limits we talked about earlier. The key thing to note is not that we get a benefit from the increased oxygen itself, but rather by virtue of us having less nitrogen in the breathing mix.
Are there any risks or special procedures?
Yes, there are some risks to diving with enriched air, but these are very manageable and will be covered in detail during your Nitrox diver training.
Does that mean that I can dive for longer on a Nitrox tank?
Well, yes and no. You can stay at a particular depth for longer before reaching your no decompression limit. However, the size of the cylinder does not change, so ultimately you will be bound by your air consumption rate. (How quickly you breathe the air from your tank). If your air consumption is limiting you time underwater, you might consider taking the PADI Peak Performance Buoyancy course at the same time as your Nitrox course, and then you would truly be able to see the benefit of Nitrox diving with your improved air consumption.