Each haemoglobin molecule can carry a maximum of four molecules of O₂. Binding of oxygen with haemoglobin is primarily related to partial pressure of O₂. Partial pressure of CO₂, hydrogen ion concentration and temperature are the other factors which can interfere with this binding. A sigmoid curve is obtained when percentage saturation of haemoglobin with O₂ is plotted against the pO₂. This curve is called the Oxygen dissociation curve and is highly useful in studying the effect of factors like pCO₂, H₊ concentration, etc., on binding of O₂ with haemoglobin. In the alveoli, where there is high pO₂, low pCO₂, lesser H₊ concentration and lower temperature, the factors are all favourable for the formation of oxyhaemoglobin, whereas in the tissues, where low pO₂, high pCO₂, high H₊ concentration and higher temperature exist, the conditions are favourable for dissociation of oxygen from the oxyhaemoglobin.

Factors that shift the oxygen dissociation curve to the right shift include:

1. Low partial pressure of oxygen: When the partial pressure of oxygen is low, such as in high altitudes or in lung diseases, the oxygen dissociation curve shifts to the right. This allows for greater unloading of oxygen from hemoglobin to the tissues.

2. High concentration of carbon dioxide: Increased levels of carbon dioxide in the blood, such as during exercise or in conditions like respiratory acidosis, cause the oxygen dissociation curve to shift to the right. This shift is known as the Bohr effect and facilitates oxygen unloading in tissues with high metabolic activity.

3. High number of hydrogen ions: Increased levels of hydrogen ions, which occur in conditions like acidosis or during intense exercise, shift the oxygen dissociation curve to the right. This is also part of the Bohr effect, where a decrease in pH promotes the release of oxygen from hemoglobin.

4. Low body temperature: Low body temperature shifts the oxygen dissociation curve to the right. This is seen in conditions like hypothermia, where decreased temperature decreases the affinity of hemoglobin for oxygen, allowing for easier unloading of oxygen to the tissues.

5. Daily exercise: Regular exercise increases carbon dioxide levels and hydrogen ion concentration in the blood, leading to a right shift in the oxygen dissociation curve. This adaptation allows for efficient oxygen delivery to muscles during physical activity.

6. Hemoglobin of babies or fetal hemoglobin: Fetal hemoglobin has a higher affinity for oxygen compared to adult hemoglobin. This difference is due to the presence of gamma globin chains in fetal hemoglobin. The higher affinity for oxygen allows fetal hemoglobin to effectively extract oxygen from the mother's blood across the placenta. This characteristic of fetal hemoglobin results in a left shift in the oxygen dissociation curve.

In summary, factors that shift the oxygen dissociation curve to the right include low partial pressure of oxygen, high concentration of carbon dioxide, high number of hydrogen ions, low body temperature, and daily exercise. However, the hemoglobin of babies or fetal hemoglobin causes a left shift in the oxygen dissociation curve due to its higher affinity for oxygen.