The nose is the entrance door of the air in our body and intervenes in an essential event for survival: breathing.
Since breathing is vital, Mother Nature has provided us with an emergency channel that intervenes in the event of a blockage of the nose: oral respiration. If it were not possible to breathe from the mouth we would risk dying suffocated even after a common cold.
Breathing through the mouth must be an exceptional event and of short duration, because the air flows that pass through this channel do not enjoy the effect of air conditioning provided by the nose. The breathing of non-conditioned air over time has serious repercussions on the lower airways (trachea and bronchi).
To give an idea of the quantities of air involved, it should be borne in mind that in an adult person, in a state of rest, pass through the nose about 6 l of air per minute, to reach 50-70l/minute, during intense physical efforts! The passage of such quantities of air is considerable work for the internal structures of the nose.