Oxygen dissociation curve shifts to the right by all of the following except:
A shift to the left indicates acceptance of oxygen by hemoglobin and the shift to right indicates dissociation of oxygen from hemoglobin. Factors favoring shift to right are —

Decreased PO2
Increased PCO2 (Bohr effect)
Increase in H+ concentration or decreased pH
Excess of 2, 3 DPG (exercise, high altitudes)
Increased body temperature
Rise in temperature
Rise in carbon dioxide tension
Rise in pH
Rise in H + ion