Which of the following most correctly describes the Bohr effect?

  1. A decrease in PaCO2 will decrease the affinity of oxygen for haemoglobin
  2. An increase in PaCO2 will promote oxygen offloading in the tissues
  3. A decrease in pH will decrease the affinity of oxygen for haemoglobin
  4. An increase in temperature will increase the affinity of oxygen for haemoglobin