What makes me suspicious of the CO diagnosis is the method of recovery. Normally, the patients would be given oxygen to breath and that would reduce their CO levels by 50% every 80 minutes. Walking around in fresh air (as is reported) reduces CO levels (actually, the COHb level) by 50% every 320 minutes (
https://en.wikipedia.org/wiki/Carbon...ning#Treatment).
My father started with Northwest Orient in 1968.
He told me a tale: in the old days, a crew flew overseas, and then rode in an ancient vehicle to the hotel. The vehicle had an exhaust leak in the passenger compartment.
Everyone decided to go out and drink except the captain. He went upstairs and went to bed. The captain died from carbon monoxide poisoning. The rest of the crew stayed up long enough to safely get the CO out of their system.
The moral of the story: you have to go at least get one drink when you arrive at the hotel. You never know if you've been poisoned.....