Bohr effect is a property of haemoglobin first escribed in 1904 by the Danish physiologist Christian Bohr (father of physicist Niels Bohr), which states that in the presence of carbon dioxide, the oxygen affinity for dissociation of respiratory pigments, such as haemoglobin, decreases; because of the Bohr effect, an increase in blood carbon dioxide level or a decrease in pH causes haemoglobin to bind to oxygen with less affinity.