What is the relative humidity of the hypopharynx?

The relative humidity of the hypopharynx is approximately 95%. This high level of humidity is critical for maintaining the health of the respiratory tract and ensuring effective gas exchange. The ventilation process requires air to be adequately warmed and moistened before it reaches the lower airways and the alveoli, which are critical for efficient oxygen absorption and carbon dioxide removal.

The mucosal surfaces of the upper and lower airways are lined with ciliated epithelial cells and mucous glands, which contribute to this high humidity level by secreting mucus that traps particles and pathogens while also adding moisture to the inspired air. Achieving this nearly saturated humidity helps to protect the delicate tissues of the respiratory system, preventing irritation and maintaining the necessary conditions for optimal respiratory function.

In contrast, lower humidity levels can lead to dryness of the airways, irritation, and potential complications, particularly in individuals with respiratory conditions. Hence, the hypopharynx functions as an important area for conditioning the inspired air, which is reflected in its high relative humidity.