Cigarette filter

A cigarette filter is a component of a cigarette, along with cigarette paper, capsules and adhesives. The filter may be made from cellulose acetate fibre, paper or activated charcoal (either as a cavity filter or embedded into the cellulose acetate). Macroporous phenol-formaldehyde resins and asbestos have also been used in cigarette filters. The acetate and paper modify the particulate smoke phase by particle retention (filtration), and finely divided carbon modifies the gaseous phase (adsorption). Filters can reduce "tar" and nicotine smoke yields up to 50%, with a greater removal rate for other classes of compounds (e.g., phenols), but are ineffective in filtering toxins such as carbon monoxide. Most factory-made cigarettes are equipped with a filter; those who roll their own can buy them from a tobacconist.

In 1925, Hungarian inventor Boris Aivaz patented the process of making a cigarette filter from crepe paper.

From 1935, a British company began to develop a machine that made cigarettes incorporating the tipped filter. It was considered a speciality item until 1954, when manufacturers introduced the machine more 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. Production of filter cigarettes rose from 0.5 percent in 1950 to 87.7 percent by 1975.

Between the 1930s and the 1950s, most cigarettes were 70 mm long. The modern cigarette market includes mainly filter cigarettes that are 80 mm (in boxes), 85 mm (in softpack), 100, or even 120 mm long.

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