less scientific or clinical sounding yet reassuring term for a gas that's okay to breathe than "breathable gas"?

In the first sentence of the SE question In simple terms, how does the way space suits manage breathable gas differ from how scuba gear does it? I explain:

I say "breathable gas" because what’s in the tank can be a variety of mixtures and I don’t know a single word for gas mixture you can safely breathe.

In the interest of biological and medical research and in deep sea diving and space exploration people have been give all kinds of gas mixtures with witch breathe to stay alive and conscious¹. Sometimes pure oxygen, sometimes an oxygen-helium mix, etc.

The unifying feature would be to allow a proper amount of oxygen to the person’s blood through the lungs, and otherwise "do no harm".

For water we have potable water. For air, we obviously have breathable gas.

But someone giving you a canister and saying "Here, inhale some of this. Trust me, it’s breathable gas" doesn’t sound reassuring.

Question: Is there a less scientific or clinical sounding yet reassuring term for a gas that’s okay to breathe?

The phrase "fit to breathe air" (perhaps with some hyphenation) is not scientific or clinical and apparently means the same as breathable. But is there a less awkward construction for that or something different and yet obvious?

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¹here I’m excluding anesthetic mixutres or things that have other adverse or impairing effects (e.g. tear gas and worse).