Can you tell me how could carbon monoxide poisoning happen?

Exposure: Carbon monoxide has a stronger affinity (bonding) to the red cells hemoglobin molecule than oxygen, so the presence of increased levels of carbon monoxide in air can gradually displace the oxygen.As it circulates in the blood, the hemoglobin is not carrying useful oxygen, so the cells starve and the poisoning occurs.Cell death can occur if oxygen does not return in time.