Since when is CO2 a pollutant?
Look up "photosynthesis."
The EPA doesn't say it's necessarily a pollutant. It's the atmospheric concentrations increasing because of human activity.
IANAL, but I believe that legally, it was George H.W. Bush's Clean Air Act that set up the regulation of the six gases, including carbon dioxide.
Scientifically, one might consider it a pollutant if it's added to the system faster than the system can react in quasiequilibrium (or homeostasis).
Look up "photosynthesis."
Okay, I see that in the presence of arsenite, adding carbon dioxide and photons from the sun yields arsenate through photosynthesis. Arsenate can interrupt glycolysis, making 1-arseno-3-phosphoglycerate instead of 1,3-bisphosphoglycerate, losing the energy-carrying adenosine-5'-triphosphate molecule that would have been produced.
Okay, so I guess since that's a natural photosynthetic pathway, arsenic can't be a pollutant even though it is toxic.
And since we're all carbon-based life forms, you wouldn't mind if I dumped soot all over everything. It's natural, after all. Or if I released phosphates and nitrates into the lakes and streams, turning them into stinking messes. Since they're natural and they help the algae grow, they must not be pollutants, right?
And heck, those could come in manure form. It helps plants grow...you wouldn't mind if I spewed it all over everywhere, would you?--it can't be a pollutant, after all.
My, oh, my...what a world that would be.