Respiratory Deposition

:: Section 4

Deposition Mechanism

II. Settling

When flow velocity is small and the airway dimension is small, settling then becomes an important role for large particles. Just like all objects on earth are subject to the gravitational force, a particle settles onto the airway surface when it moves toward the earth. It's especially effective in horizontally oriented airways. Therefore, it is the most important in the distal airways (those farthest from the trachea).