How can you determine what the direction of the shift is in the Bohr effect?

Haemoglobin acts as the Oxygen transportation system for the body. It is comprised of 4 polypeptide chains (quaternary protein structure) and each chain has an attached haem group. Each haem group allows an oxygen molecule to bind (associate) with it, so the haemoglobin molecule can carry up to 4 Oxygen molecules. The partial pressure of Oxygen lets us know how much oxygen is present, and the affinity (ability of haemoglobin to load oxygen molecules) depends on the oxygen concentration.If there is a high PP of oxygen then there is a higher affinity. Essentially, oxygen is loaded up where there is a lot and taken to areas where there is little (low PP e.g respiring tissues). When there is a high PP of carbon dioxide, oxygen is more readily unloaded (as respiring tissues release CO2). The Bohr effect shows the rate of Oxygen dissociation under different PP of Carbon Dioxide. To determine the shift in the Bohr effect the PP of Carbon Dioxide must be considered. The lower the pp of Carbon Dioxide, the slower the unloading of Oxygen (as it unloads more readily at higher PP of CO2) and therefore the higher the blood saturation of Oxygen as it has not released its Oxygen to tissues. Therefore the graph shifts to the left with lower PP of CO2 and to the right with higher PP of CO2.