Excess oxygen is actually harmful to humans, but all the climate warnings are about losing oxygen, not nitrogen edit: but when we look for habitable planets, our focus is ‘oxygen rich atmosphere’, not ‘nitrogen rich’, and in medical settings, we’re always concerned about low oxygen, not nitrogen.

Deep sea divers also use a nitrogen mix (nitrox) to stay alive and help prevent the bends, so nitrogen seems pretty important.

It seems weird that our main focus is oxygen when our main air intake is nitrogen. What am I missing?

edit: my climate example was poor and I think misleading. Added a better example instead.

    • LillyPip@lemmy.caOPEnglish
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      9 months ago

      That makes sense, thanks, since our threshold for co2 is less than 0.5%.

      I may have worded my question poorly; I’m more asking why low oxygen is a problem vs low nitrogen. In retrospect, my climate focus may be distracting. It was what made me wonder about this in the first place, but the medical and scuba points are much more relevant. That has little to do with co2 (I think?) and more to do with the relative compounds in our air.

      I’m still confused why we hear about oxygen but never nitrogen. Another example: when we look for habitable planets, the focus is ‘oxygen rich atmosphere’, but not ‘nitrogen rich’.

      • sexy_peach@feddit.deEnglish
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        9 months ago

        Maybe nitrogen could be replaced with other gases, but we need oxygen in our lungs and bloodstream to survive. So maybe it’s more important for our survival?

          • LillyPip@lemmy.caOPEnglish
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            9 months ago

            That explains it very well, thank you!

            So from what I understand, we need a rather precise amount of oxygen plus a large amount of an inert gas – pretty much any inert gas, barring a few that have narcotic effects. So nitrogen isn’t special, except that it’s inert and doesn’t get us high.

            But I’m also curious whether the reactive gas in low quantities (oxygen) can also be replaced. I’m not a chemist, and this is fascinating. I’ll keep reading.

            Thanks again!

            • Telorand@reddthat.comEnglish
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              9 months ago

              I’m not a biologist, doctor, or chemist, but my guess is “no.” We have evolved to use oxygen to create energy within our cells, not some other gas.

              I would hazard an additional guess that it’s not a simple matter to just swap out the oxygen molecules for something else. Carbon monoxide binds better and more readily to our cells, yet that mixture would asphyxiate you.

              https://www.nhlbi.nih.gov/health/lungs/breathing-benefits

              The cells need this oxygen to make the energy your body needs to work. When cells make that energy, they create the waste product carbon dioxide.