What is a disadvantage of breathing through the mouth?

Breathing through the mouth has several disadvantages, and one significant concern is that inspired air is purified insufficiently when entering the respiratory system. The nose is equipped with mucous membranes and tiny hairs (cilia) that play a critical role in filtering out dust, allergens, and microorganisms from the air we breathe. When air is inhaled through the nose, it encounters these defenses, contributing to a cleaner air supply that reaches the lungs.

In contrast, when breathing through the mouth, this filtration process is largely bypassed. As a result, airborne pollutants and pathogens can enter the respiratory tract more easily, potentially leading to increased risk of infections or respiratory issues. While other aspects of mouth breathing, such as air temperature or humidity, are disadvantaged, it is the insufficiency in purification that is particularly relevant, highlighting why mouth breathing is generally less favorable for respiratory health.