Nose hair does indeed have a purpose, and it is not to keep the manufacturers of nose hair trimmers in business. Nose hair, also known as olfactory cilia, is one of the body's first lines of defense against harmful environmental pathogens such as germs, fungus and spores. When a person inhales unfiltered air through his or her nose, he or she is also inhaling whatever solid particles are contained in that air. The thicket of nose hair contained in each nostril helps to trap the larger particles in a sticky layer of mucus. This is why hygienists discourage people from completely eliminating their nose hair while grooming.

Another purpose for nose hair is to provide additional humidity to the inhaled air. As the inhaled air passes through the nasal passages, the mucus and nose hair provide heat and moisture. Humidity is an important factor for the rest of the respiratory system, such as the larynx and lungs. Nose hair in the form of tiny cilia also draw solid particles towards the interface between the nose and throat. Harmful debris is generally directed towards the back of the throat and esophagus for swallowing, while the filtered air continues towards the larynx and lungs.

While excessive nose hair may be considered unsightly, it should never be completely removed. Those who choose to remove almost all of their nose hair may find themselves very susceptible to allergy attacks, sinusitis and respiratory infections. Older people may also want to minimize their nose hair trimming because it often takes longer for the clipped hairs to grow back. Nose hair serves the same filtering purpose as ear hair, both of which may become a little overgrown as time goes by.

Nose hair can be safely trimmed with specialized rotary clippers or mechanical trimmers, but great care should be used to prevent infection or irritation from ingrown hairs. Excessive nose hair can be trimmed until it falls below the line of the nostrils, but any aggressive trimming inside the nasal cavities should be avoided. Dryness in the nasal passages can be temporarily relieved through the use of nasal sprays, but the natural balance of mucus and functional nose hair should be maintained as often as possible.