How does the respiratory lining of the nose filter inhaled air?

The respiratory portion of the nasal cavity is lined with a moist mucous membrane that functions to clean inhaled air before it reaches the delicate tissues of the lower respiratory tract.12

This filtering process relies on two primary mechanisms:

• Mucus Secretion: Cells within the membrane wall produce mucus, which acts as a sticky trap for foreign particles such as dust, carbon, soot, and bacteria.12
• Ciliary Action: The membrane is covered with fine, hairlike projections known as cilia. These structures work to collect debris and move trapped particles out of the nasal cavity.12

Additionally, the vestibule at the entrance of the nose contains short, thick hairs called vibrissae, which provide an initial physical barrier to larger particles. Together, these components ensure that air is cleaned, warmed, and moistened during respiration.21