CO2 is not a toxic waste gas (see Myth #4). Research articles on respiration often mention such physiological parameter as dead space. It is about 150-250 ml in an average adult person: inside the nose, throat, and bronchi. This space helps to preserve additional CO2 for the human body. Indeed, during inhalations we take this CO2
enriched air from our dead space back into the alveoli of the lungs. When the mouth is used for respiration, the dead space becomes smaller, shorter and wider. Nasal passages are no longer a part of the breathing route. Air exchange is stronger as if air gets directly to lungs alveoli from outside. This reduces alveolar O2 and arterial blood CO2 concentrations. This does not take place with nose breathing. Furthermore, nasal breathing route provides more resistance for respiratory muscles as compared to oral breathing (the route for mouth breathing is shorter and it has a greater cross sectional area). During nose breathing, in order to maintain the same CO2 content in alveoli and blood, we can breathe more so that to lower CO2 content in the body. Then this will result in more mechanical work for our respiratory muscles. As an alternative, we can breathe little less while producing less mechanical work. What is the practical result? Due to an in-built tendency to minimize losses of energy, the human organism is likely, as for nose breathing, to breathe less and. hence, tolerate higher arterial and alveolar CO2, than to exert more strain on working breathing muscles.
In their study "An assessment of nasal functions in control of breathing" (Tanaka et al, 1988), Japanese researchers discovered that end-tidal CO2 concentrations were higher during nose breathing than during oral breathing. This research study revealed that a group of healthy volunteers had an average CO2 of about 43.7 mm Hg for nose breathing and only around 40.6 mm Hg for oral breathing. In practice, in terms of body oxygenation or the CP, this corresponds to 45 s and 37 s at sea level. Hence, mouth breathing reduces oxygenation of the whole body.
Each mouth breather needs to know this short summary of immediate negative biochemical effects of mouth breathing related to CO2:
– Reduced CO2 content in alveoli of the lungs (hypocapnia)
– Hypocapnic vasoconstriction (constrictions of blood vessels due to CO2 deficiency)
– Suppressed Bohr effect
– Reduced oxygenation of cells and tissues of all vital organs of the human body
– Anxiety, stress, addictions, sleeping problems and negative emotions
– Slouching and muscular tension
– Biochemical stress due to cold, dry air entering into the lungs
– Biochemical stress due to dirty air (viruses, bacteria, toxic and harmful chemicals) entering into the lungs
– Possible infections due to absence of the autoimmunization effect
– Pathological effects due to suppressed nitric oxide utilization, including vasoconstriction, decreased destruction of parasitic organisms, viruses, and malignant cells (by inactivating their respiratory chain enzymes) in alveoli of the lungs, inflammation in blood vessels, disruption of normal neurotransmission, hormonal effects.