Nasal hair

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Nasal hair.

Nasal hair, Nose hair or "olfactory cilia" consists of the usually small, hair-like cells in the nose, especially near the nostrils. Healthy cilia beat in a coordinated backward-&-forward motion on an average of sixteen times per second. Biologically, the cilia act as a filter and keep dust and dirt out of the nasal passages. They also draw liquid mucus up from the epithelium by capillary action, and thus help to maintain humidity in the air passages by trapping humidity as one exhales, while evaporation of trapped moisture on the hairs humidifies inhaled air. Cilia are in motion, beating several times per second. By this action, the ciliated cells push mucus back in towards the oropharynx where it can be either swallowed or ejected, a mechanism much like that by which the cilia in the ear canal remove cerumen and other detritus. 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, or even to destroy the cells.

In some cultures nose hair protruding from the nostrils may be thought unattractive, and the increased production of nasal cilia with age (particularly for men) is often a source of anxiety and embarassment. 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 group.