When a particle is inhaled,it comes into contact with cilia of the bronchial or nasal epithelia which beat in an upwards direction to a position where the particle can be coughed up or sneezed out.

• 一颗微粒被吸入，当它接触到支气管或鼻道上皮细胞的纤毛是，纤毛会向上摆动，把它送到能被咳嗽或是喷嚏带出的部位。