Blood is extremely dangerous when carried to the blood via the lungs by inhalation, because carbon monoxide irreversibly binds to hemoglobin to form carboxyhemoglobin, so that less hemoglobin is free to bind oxygen, and fewer oxygen molecules can be transported throughout the blood. This can cause suffocation insidiously. A fire burning in an enclosed room with poor ventilation presents a very dangerous hazard, since it can create a build-up of carbon monoxide in the air. Some carbon monoxide binds to hemoglobin when smoking tobacco. Blood for transfusion is obtained from human donors by blood donation and stored in a blood bank.
Mean corpuscular hemoglobin Mean corpuscular hemoglobin The mean corpuscular hemoglobin , or "mean cell hemoglobin" (MCH), is the average mass of hemoglobin (Hg) per red blood cell (RBC) in a sample of blood. It is reported as part of a standard complete blood count. MCH value is diminished in hypochromic anemias. It is calculated by dividing the total mass of hemoglobin by the number of red blood cells in a volume of blood. MCH=(Hgb*10)/RBC A normal MCH value in humans is 27 to 31 picograms/cell. The amount of hemoglobin per RBC depends on hemoglobin synthesis and the size of the RBC. The MCH