Nasal Pulmonary Interactions
Nasal breathing improves arterial oxygen concentrations by up to 10% and also improves the efficiency of carbon dioxide excretion from the lungs.
The nose provides an inspiratory resistance (twice that of the open mouth) forcing the diaphragm to contract against a resistance.
People who are prone to anxiety attacks would appear to have lower arterial carbon dioxide levels. People who practice relaxed diaphragmatic breathing may be less likely to present complaining of nasal congestion unlike anxious people.
Nitric oxide is a gas produced by the nose and paranasal sinuses. Nitric oxide may have a role in the sterilization of incoming air and in improving the ventilation-perfusion in the lungs.
From a physiological perspective the nose has an important role in the preparation of inspired air before inhalation into the lungs. other physiological effects such as improvements in oxygen transfer and carbon dioxide excretion would also appear to occur