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Chemical Bonding

Periodic Graphics: Gases for scuba diving

Chemical educator and Compound Interest blogger Andy Brunning dives deep into the types of air we need in order to breathe underwater

by Andy Brunning
August 27, 2018 | APPEARED IN VOLUME 96, ISSUE 34



To download a pdf of this article, visit

References used to create this graphic:

Diving, nitrogen narcosis

Moving in extreme environments: Inert gas narcosis and underwater activities

NOAA ocean explorer: Technical diving Diving and oxygen

The difference between scuba diving gas mixes

Almost everything you wanted to know about oxygen-enriched air, uhh, “nitrox” but were too busy mixing it up to ask

A collaboration between C&EN and Andy Brunning, author of the popular graphics blog Compound Interest

To see more of Brunning’s work, go to To see all of C&EN’s Periodic Graphics, visit



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Chris Sullivan (Mon Aug 27 13:03:58 EDT 2018)
Overall nicely presented, but a few issues:
- Helium can also cause the bends, not just Nitrogen.
- Nitrogen can cause bends at less than 130'. You can get the bends at 40' if you stay long enough.
- Nitrox is generally used for what is considered medium depths for recreational divers - from about 70 to 110 feet. (It's also used for accelerated decompression).
- It might be worth mentioning that Helium is easier to breathe because of its lower density.
- Helium mixes don't prevent narcosis but reduce it (if any Nitrogen is present), and risk of O2 toxicity is similarly reduced, not prevented entirely on deeper dives.

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