As you may or may not know, oxygen is only second most abundant gas in what we call ‘air’. Nitrogen takes the top spot, accounting for a whopping 78% of the gas in Earth’s atmosphere. In third place sits Argon at a measly .9%.

One reader wanted to know what would happen if we kept the oxygen the same, but replaced the nitrogen with something else. Could a person breathe the new mixture and survive to talk about it?

Breathing Gas

Swapping out the nitrogen isn’t uncommon, and sometimes necessary in certain circumstances. For instance, SCUBA divers who have to dive extremely deep will swap out the nitrogen for a helium + oxygen combo. This is due to the increased pressure divers endure when deep diving – pressures which cause nitrogen to become a narcotic when introduced into a person’s bloodstream.

This phenomenon is known as “Nitrogen Narcosis“. The effects of nitrogen narcosis on the human body are very similar to that of alcohol. Unfortunately, when your 100 feet underwater and intoxicated, it’s usually a dangerous and deadly situation. Divers replace the nitrogen in their tanks with helium to remove that risk.

Any potential gas we would want to use as a nitrogen replacement would have to be inert or mostly inert. Being inert means it wouldn’t react or undergo chemical reactions within our body. However, even inert gases have a narcotic potential when breathed, and that potential directly corresponds to each elements mass. While hydrogen has the lowest narcotic potential, its use is limited in diving because it becomes explosive when the oxygen mixture exceeds 4%.

Neon gas is also used for the same reasons as helium but is much more expensive. This relegates its use for times when a diver needs to constantly communicate as the gas does not distort a person’s voice as helium does.

What About Other Inert Gasses?

Noble gases like Xenon are not used because most are not sufficiently inert. Xenon gas has a strong effect on the human brain – it acts as a powerful anaesthetic. And it’s quite an effective one at that. Doctors and surgeons would love to be able to use it to keep people unconscious during surgery but thanks to the cost of production, its use in the medical field is limited.

Xenon gas is also used in light bulbs, MRI machines as a contrast agent, lasers and even as propellant in cutting edge ion drives for space propulsion.

Argon gas could technically be used, but since it is 2x more narcotic than nitrogen, its use is limited to industrial and scientific research. Argon is also extremely expensive. Any benefits it could provide would be outweighed pretty heavily by its disadvantages.