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Cigarette filter

A cigarette filter has the purpose of reducing the amount of smoke, tar, and fine particles inhaled during the combustion of a cigarette. Filters also reduce the harshness of the smoke.

History

In 1925 Hungarian inventor Boris Aivaz patented the process of making cigarette filters from crepe paper, with some variants including cellulose wadding, during experiments at the Ortmann plant of Bunzl. Aivaz produced the first cigarette filter from 1927 in co-operation with Bunzl's Filtronic subsidiary, but up take was low due to a lack of machinery to produce cigarettes with the filtered tip.

From 1935, a British company began developing a machine to make cigarettes that incorporated the tipped filter, but it 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 and a "light" cigarette in the United States.

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

Manufacture

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 2.35 - 2.55 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.

The U.S. 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.

"Light" cigarettes

In "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. In theory, this should make the cigarette "safer" than full flavor ones. In practice, however, the average smoker compensates by inhaling more deeply or by covering parts of the holes with fingers or lips. Because of this, smokers of light cigarettes can be exposed to equal or greater doses of carcinogens and tar than they would be with medium tar cigarettes.

Disposal

The cellulose acetate most cigarette filters are made from is a biodegradable resistant material. Depending on conditions, estimates for the time taken for them to degrade range from British American Tobacco's 10 months - 3 years, to 10-15 years.

This resistance to biodegrading is a factor in littering, environmental damage and suggested lung damage. In the 2006 International Coastal Cleanup, cigarettes and cigarette butts constituted 24.7% of the total collected garbage, over twice as much as any other category.

References

External links

How stuff works: Cigarette filters
Article on Tobacco Control website on the "defective design" of cigarette filters ("Essentially, this journal offers a one-stop shopping guide for anti-smoking literature and other resources." - Philip Morris 1992.)
[[Public Broadcasting Service|PBS]'s NOVA Search for a Safer Cigarette]
UCSF Tobacco Industry Videos Collection
UCSF Tobacco Industry Audio Recordings Collection