Carbon dioxide poisoning is quite painful. Respiratory distress is caused by the inability to remove CO2 from the blood. Respiration is controlled by sensing CO2 levels. There was a village in Africa that was wiped out about 10 years ago when a volcano caused a local build up of CO2. An excruciating way to die. Carbon Monoxide is deadly, but much slower. It bonds to hemoglobin preventing the absorption of oxygen, but it is a very slow and nauseating process. If I had to be executed, I would probably choose nitrogen asphyxiation over any other method.
Thank you for these details,LIM. It’s a precious thing to learn something new each day. Cheers!