Heliox — What It Is and Why It Matters
Heliox is a breathing gas mixture containing only helium and oxygen, with no nitrogen. Used primarily in commercial and military diving for extreme depths, heliox completely eliminates nitrogen narcosis. However, it introduces its own challenges: high cost, high thermal conductivity (divers get cold faster), and the need for extended decompression due to helium's fast diffusion into tissues.
In recreational and sport technical diving, trimix (which includes some nitrogen) is far more common than pure heliox because it is less expensive and still provides adequate narcosis reduction for most technical dive profiles.
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Frequently Asked Questions
Why is heliox not used more in recreational diving?
Cost is the primary reason — pure helium is expensive, and heliox fills are several times the price of trimix fills, which already cost significantly more than air. Trimix provides sufficient narcosis reduction for sport technical diving depths without the extreme cost.
Does my dive computer support heliox?
Any dive computer that supports trimix can handle heliox — you simply set the nitrogen fraction to 0% and specify the helium and oxygen percentages. However, this is only relevant for advanced technical divers with appropriate training.
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