Nasal hair

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Nasal hair, Nose hair or olfactory cilia are small hair-like cells. They are in the nose. Most of them can be found near the nostrils. Biologically, the cells act as a filter. They keep 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. They trap humidity when air is exhaled. The evaporation of trapped moisture on the hairs humidifies the inhaled air.

Cilia are in motion, beating several times per second. Healthy cilia beat up to 16 times a second. By this action, the ciliated cells push mucus back in towards the oropharynx where it can be either swallowed or ejected. The cilia in the ear canal remove cerumen (and other detritus) in much the same way. Exposure to cold is thought to slow the vibration of the cilia, contributing to the buildup of mucus; diesel fumes and other pollutants are thought to have similar effect.

Loss of nasal cilia due to alopecia areata (a form of hair loss that causes bald spots) has been linked to increased severity of asthma, seasonal allergy and atopic dermatitis (skin irritation caused by hereditary hyper-sensitivity). Smoking is widely held to interfere with cilia function. It may even destroy the cells.

Some cultures consider nose hair coming out from the nostrils to be unattractive. The increased production 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 miniature rotary clippers and attachments for electric shavers. However, given the function of nasal cilia, many physicians recommend trimming them lightly, if at all. There is evidence that ciliar motility regularly declines with advancing age, a fact which may be implicated in the higher incidence of respiratory infections in this age group.