A cigarette filter is a component of a cigarette designed to reduce the inhalation of harmful substances in tobacco smoke. Typically made from cellulose acetate, a type of plastic fiber, the filter is located at the end of the cigarette that is held between the lips during smoking. It functions by trapping some particulate matter, including tar, through mechanical filtration as the smoke is drawn through its fibrous structure.
Filters may also include perforations (known as filter ventilation) that allow ambient air to mix with the smoke, which can dilute the measured concentrations of tar and nicotine in standardized smoking machine tests. However, this does not necessarily correspond to reduced health risks for smokers, as behavioral compensations—such as inhaling more deeply or smoking more cigarettes—may offset potential benefits.
The use of filters became widespread in cigarette manufacturing during the mid-20th century, particularly as public awareness of the health risks of smoking increased. Filtered cigarettes were marketed as a "safer" alternative to unfiltered ones, though medical and public health authorities have emphasized that no cigarette is safe, and filtration does not eliminate the health risks associated with smoking.
Modern cigarette filters do not significantly reduce the overall health risks of smoking-related diseases, including cancer, cardiovascular disease, and chronic obstructive pulmonary disease. Additionally, used cigarette filters are a major source of environmental litter, as the cellulose acetate material is not readily biodegradable.
Accurate information is not confirmed regarding any substantial long-term health benefits conferred by cigarette filters to smokers.