It can be brought down even faster with hyperbaric oxygen therapy. Hyperbaric chambers are reasonably common, due to usage in both (SCUBA) diving related medicine and various therapies for wound care.
According to the toxicity curve from wikipedia, even at 2.5 bar, you wouldn't start to see issues until ~4 hours have past. That's enough time to remove quite a bit of CO.
What's the limit on that? The link you posted says 2.5 atm of pure oxygen but how does that not cause oxygen toxicity?