Reduction in pH of blood will

Reduction in pH of blood will decrease the affinity of haemoglobin with oxygen. Reduction of pH occurs when ${\mathrm{H}}^{+}$concentration increases. When haemoglobin binds to ${\mathrm{H}}^{+}$, it unloads oxygen (Bohr effect) in the tissues,  low ${\mathrm{pO}}_2$, high ${\mathrm{pCO}}_2$, high ${\mathrm{H}}^{+}$ concentration (low pH) and higher temperature favour the dissociation of oxygen from the oxyhaemoglobin.