Nasal hair are small hair-like cells in the nose. Most of them can be found near the nostrils. The purpose of these hairs is to act as a filter, keeping dust and dirt out of the nasal passages. They also draw liquid mucus up from the epithelium by capillary action. In that way, they help to maintain humidity in the air passages and stop them from drying out. The hairs trap moisture as air is breathed out. The evaporation of trapped moisture on the hairs increases the humidity of air as it is breathed in. Note that nasal hair is different from the cilia found in the nose, which are part of the olfactory system.
Some cultures consider nose hair coming out from the nostrils to be ugly. The increased growth of nasal cilia with age (particularly for men) is often a source of anxiety and embarrassment. A number of devices have been sold to trim the nose hair, including small rotary clippers and attachments for electric shavers. However, given the role of nasal cilia, many doctors recommend trimming them lightly, if at all. There is evidence that the movement in the ciliar slows down with age. This may be the reason that old people have more respiratory infections.