The nose functions as a respiratory pathway to warm, humidify and filter inspired air. It is also the organ of olfaction, and a resonator for speech.

The nasal cavity is lined by respiratory mucosa, which is pseudostratified ciliated columnar epithelium containing numerous mucous and serous glands. Mucous and cilia serve to waft particulate matter toward the nasopharynx, whilst evaporation of watery secretions from the serous glands and excellent blood supply ensures efficient warming and near 100% humidification.

Note that intubation bypasses these important functions.