Medal Winners: Air Traffic Control Tapes

Try searching on the terms "carbon dioxide poisoning" and
"Hypercapnia" instaid. CO2 is toxic but is nowhere near as toxic as CO.
CO2 can act as a simple asphyxiant and kill by displacing oxygen or it
can kill from its toxic effects. It's much more likely to kill by
asphyxiation. It generally takes some unusual circumstances to
encounter its toxic effects and it takes a fair amount of time for
these effects to become dangerous. This is probably why it's not
usually considered a poison, usually it will suffocate you long before
it can poison you. CO will nearly always kill from its toxic effects
rather than simple asphyxiation because there is rarely enough of it
around to displace much oxygen in the atmosphere. CO2 poisoning is
usually only a concern if you are breathing a canned atmosphere with
plenty of oxygen but no way to get rid of the CO2.