Do Saitama and Garou have superhuman hold breathing capabilities, or no need for air at all?

Question

In One Punch Man manga chapter #167

Saitama and Garou have a fight in Io, the Jupiter satellite, where there is no air

Do Saitama and Garou have superhuman hold breathing capabilities, or no need for air at all?

Answer 1

Implicitly: Superhuman hold breath for Saitama, at least; put possibly a greater power.

Why:

In Chapter 168, after a fairly long (by Saitama standards) battle on Io, Saitama eclipses Garou entirely and emits a Serious Sneeze. A sneeze strong enough to travel all the way to Jupiter and blast away its atmosphere enough to expose its core (and wreck most of Io and send both of them flying away, seemingly in excess of escape velocity of Io and Jupiter). This would require a massive amount of air, which Saitama must have simply been holding onto this entire time. This even despite no apparent effort being made to actually hold his breath or to in any way stop air from escaping his body.

The ridiculous part:

Indeed, without attempting to actually calculate it, I would hazard the guess that the effects on Jupiter would require well in excess of the entire atmosphere of Earth to have been ejected during the sneeze. If so, perhaps the answer isn't Super Hold Breath, but rather Super Create Air: he produces whatever air he needs to do what he wants to do it, or an effect equivalent to it. So he wants to talk, so he has enough to talk; he wants to sneeze or fart prodigious volumes and velocities, and he produces enough to do that.

For Garou:

In his cosmic form he is said to have connected to the means of producing all forms of energy in the cosmos. So he could create breathable air for himself on the fly through, say, nucleosynthesis (Big Bang style if need be: create tons of energy, condense it into air molecules). He could also simply create all the side effects of having adequate air on the fly: he can create the soundwaves to talk, he can just give his cells the energy needed without relying on chemical reactions, stimulate his nervous system to send the "yep, we're breathing just fine" signal, etc.

Combined conclusion for Saitama:

Combined with Saitama's ability to grab and manipulate dimensional portals at will like some sort of Looney Tunes character, as well as his ability to evidently "mimic/copy" Garou's power so well he can achieve a time travel ability Garou could not, which itself explicitly involves control at an atomic scale at least, I would conclude that even "Super Create Air" is underselling what Saitama is doing. He seems to instead have a "Do whatever I want" reality-bending style of power. He's limited (upwards at least; maybe there's a floor on how weak he can be) only by his conception of what he could do if he wanted to: he doesn't fly because he doesn't think that's possible, but he can fart with impossible control to achieve space travel along precise paths; he doesn't think he can time travel until Garou insists he can by just mimicing him (which he says is actually Saitama using God's power without being connected to or corrupted by God). He's too focused on dealing with Garou after Genos's death to realize he should have problems breathing (or even being able to talk at a distance), so he has no such problems as he defaults to "duh, of course I can breathe, doesn't even require me to think about it to do that", etc.