ok so I stumbled cross this becuse in n episode of ST:TNG (S3E01 "Evolution") there is mlfunction tht releses "nitrogen oxide" on the bridge nd everyone is coughing.
so I looked up different gses tht hve N nd O, none hve tht exct nme. noticed tht nitric oxide is pprently only produced when you brethe in through your nose:
Nasal breathing produces nitric oxide within the body, while oral breathing does not.
nywy the reference led to this rticle
This is absolutely a thing. I was skeptical of this at first too, thought it was a joke, but nah. Stopping mouth breathing really is beneficial to health. I started taping my mouth shut at night to prevent mouth-breathing while sleeping about a year ago, and I am legit grateful I did.
While I don't buy into everything its proponents espouse, I'd recommend looking into Buteyko breathing.