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A cigarette filter has the purpose of reducing the amount of smoke, tar, and fine particles as combustion products from a cigarette, being inhaled. All this makes the smoke seem somewhat less harsh to the smoker.

Contents 1 History 2 Manufacture 3 "Light" cigarettes 4 Ultra-fine fibers 5 See Also 6 External links

The filter cigarette was a specialty item until 1954, when manufacturers introduced it broadly following a spate of speculative announcements from doctors and researchers concerning a possible link between lung diseases and smoking. Since filtered cigarettes were considered "safer", by the 1960s, they dominated the market.

With classic filter cigarettes, the filter is covered with a cork-colored mouthpiece. Nowadays, some cigarette brands use a white mouth piece, especially those which are oriented to a predominantly female target group, it is also used to signify a menthol cigarette in the United Kingdom.

Most factory-made cigarettes are equipped with a filter; those who roll their own can buy them in a tobacco store.

The raw material for the manufacture of cigarette filters is cellulose (obtained from wood). The cellulose is acetylated, dissolved, and spun as continuous synthetic fibers arranged into a bundle called tow. The cellulose is a substituted diacetate (actually 1.5 to 2.0 substitution range) cellulose, due to its chemical and physical processing. This tow is opened, plasticized, shaped, and cut to length to act as a filter.

In the early 1950s Kent brand cigarettes used crocidolite asbestos as part of the (Micronite) filter. Asbestos fiber is heatproof, insoluble and forms extremely fine fibers--but has been proven to cause lung cancer when inhaled.[1]

The initial use of filters in cigarettes was a move on the part of the manufacturers to reduce the production costs and increase profits.^{[citation needed]} The US Department of Agriculture price support for the various grades of tobacco favored the use of #4 and 5 grade, included what were known as sand lugs and floor sweepings at 10 cents/lb versus #1 grade at close to 70 cents. During the 1940s, it was less expensive to manufacture a filtered cigarette than a regular one. The filter masked the harsh cheap tobacco. It was simple enough to test this known fact. A filtered cigarette such as Viceroy or Parliament with the filter removed were practically unsmokable.

The decline in sales in the U.S. of top grade tobaccos as a result of this shift left the US government having to buy and store tremendous quantities of top grades, which were sold at a loss (to the US taxpayer) to European manufacturers.^{[citation needed]}

Especially with "light" cigarettes, the filter is perforated with tiny holes in order to dilute the smoke with air. As such, it contains less tar and nicotine. It is said however, in practical use, the average smoker covers parts of the holes with his fingers and lips, so that the inhaled smoke contains a higher concentration of tar and nicotine than determined by the smoke-testing machines and as printed on the pack. Anecdotal evidence indicates that many smokers can differentiate between light and regular cigarettes.^{[citation needed]}

Cigarette filter fibers are considered to be much too large in diameter to be inhaled into the lungs. With inhalation, theoretically, fine fibers are transported into the lungs and the amount of inhaled substances increases. At the same time, the greater resistance when inhaling leads to a longer suction phase and thus to a deeper inhalation than with non-filter cigarettes--again theoretically. There is no conclusive scientific evidence that filter cigarettes are less harmful than non-filtered.

• Nicotine
• Tobacco smoking
• Chemicals in a cigarette
• List of additives in cigarettes

• How stuff works: Cigarette filters
• Article on Tobacco Control website on the "defective design" if cigarette filters ("Essentially, this journal offers a one-stop shopping guide for anti-smoking literature and other resources." - Philip Morris 1992.)
• PBS's NOVA Search for a Safer Cigarette