How long does co stay bound to hemogloben - minutes, hours, or days after leaving co contaminated room.?

Half gone after 4 hr. Carbon monoxide (co) stays tightly bound to hemoglobin, forming carboxyhemoglobin. Because the co doesn't easily come off, the hemoglobin is not freed to pick up oxygen. Studies show carboxyhemoglobin's half-life to be about 4 hours (3-5 hr) in regular air, about 1 hour (30-90 minutes) when breathing 100% oxygen for treatment of co poisoning, and about 15-23 minutes in hyperbaric oxygen (2.5 atm).
Permanently. Some might be displaced if exposed to higher levels of oxygen. Basically it stays till the RBC dies in about 3-4 months and is replaced by a new rbc.