The benefits of inhaling through the nose and exhaling through the mouth include: the role of humidifying, warming and purifying the air inhaled; and the role of increasing the humidity of the mouth. The air contains a variety of dust, particles and some harmful substances, so the air is always turbid, so when inhaling through the nose, the air enters the nasal cavity, it will be adsorbed in the mucus above the nasal hairs, thus playing a role in purifying the air. When the purified air from the nasal cavity into the lower respiratory tract process, and can play a role in humidification and heating, to avoid dry cold air into the lower respiratory tract and make the respiratory mucosa irritation, congestion and edema. Exhaling slowly through the mouth can reduce the effect of hot and cold airflow changes on the regulatory function of the nasal mucosa and increase the role of oral mucosal humidity.