When the exchange of oxygen takes place between the blood and the alveolar air, the partial pressure of the oxygen increases, and that time the carbaminohemoglobin dissociates to form carbon-dioxide and $\mathrm{H}\mathrm{b}–{\mathrm{N}\mathrm{H}}_2$ . This reduction of the carbon-dioxide content of the haemoglobin due to an increase in the partial pressure of oxygen is also known as the Haldane effect.