A nose filter or nasal filter is an

air filter A particulate air filter is a device composed of fibrous, or porous materials which removes solid particulates such as dust, pollen, mold, and bacteria from the air. Filters containing an adsorbent or catalyst such as charcoal (carbon) may als ...

designed to fit inside the human

nostrils A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbi ...

to prevent the nasal inhalation of

allergen An allergen is a type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body. Such reactions are called allergies. In technical terms ...

s, pollutants, and irritants such as dust, smoke, and foul odors. They are generally not intended for protection against toxic or injurious materials such as

asbestos Asbestos () is a naturally occurring fibrous silicate mineral. There are six types, all of which are composed of long and thin fibrous crystals, each fibre being composed of many microscopic "fibrils" that can be released into the atmosphere b ...

. The filters are available in various sizes, and typically have a center clip to facilitate insertion and removal. Some designs incorporate an adhesive tab or have a flexible bridge to make the product form fitting so it more easily stays in place.

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Further reading