Tar (tobacco residue)

Tar is the common name for the resinous, partially combusted particulate matter produced by the burning of tobacco and other plant material in the act of smoking. Tar is toxic and damages the smoker's lungs over time through various biochemical and mechanical processes. Tar also damages the mouth by rotting and blackening teeth, damaging gums, and desensitizing taste buds. Tar includes the majority of mutagenic and carcinogenic agents in tobacco smoke. Polycyclic aromatic hydrocarbons (PAH), for example, are genotoxic via epoxidation.

There is a common misconception that the tar in cigarettes is equivalent to the tar used on roads. As a result of this, cigarette companies in the United States, when prompted to give tar/nicotine ratings for cigarettes, usually use "tar," in quotation marks, to indicate that it is not the road surface component. Tar is occasionally referred to as an acronym for total aerosol residue, a backronym coined in the mid-1960s.

Tar, when in the lungs, coats the cilia causing them to stop working and eventually die, causing conditions such as lung cancer as the toxic particles in tobacco smoke are no longer trapped by the cilia but enter the alveoli directly. Thus, the alveoli cannot come through with the process that is called ‘gas exchange’ which is the cause of rough breathing.

The tar from cigarette smoke is similar to that of marijuana smoke.

One of the most known diseases caused by smoking is lung cancer. A few carcinogens commonly found in tar include benzene, acrylamide and acrylonitrile. Smoking exposes delicate cells inside the lungs directly to these compounds. This causes mutations in the DNA of the cells, which leads to cancer. According to the World Health Organization's report, "Tobacco Smoke and Involuntary Smoking," 90 percent of all cases of lung cancer are attributable to smoking.

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