In humans, the urge to breathe results from high concentrations of CO2 in the blood; there are no direct physiological sensors of blood pO2. Skindivers often hyperventilate (breathe rapidly and deeply for several minutes) just before making a dive in the belief that this will increase the O2 content of their blood.
(a) Does it do so?
(b) Use your knowledge of hemoglobin function to evaluate whether this practice is useful.