Tobacco

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Tobacco Smoke

Tobacco smoke is made up of  “sidestream smoke” from the burning tip of the cigarette and  “mainstream smoke” from the filter or mouth end. Tobacco smoke contains thousands of different chemicals which are released into the air as particles and gases. Many toxins are present in higher concentrations in sidestream smoke than in mainstream smoke and, typically, nearly 85% of the smoke in a room results from sidestream smoke. [4] The particulate phase includes nicotine, "tar" (itself composed of many chemicals), benzene and benzo(a)pyrene. The gas phase includes carbon monoxide, ammonia, dimethylnitrosamine, formaldehyde, hydrogen cyanide and acrolein. Some of these have marked irritant properties and some 60, including benzo(a)pyrene and dimethylnitrosamine, have been shown to cause cancer. One study has established the link between smoking and lung cancer at the cellular level. It found that a substance in the tar of cigarettes, benzo(a)pyrene diol epoxide (BPDE), damages DNA in a key tumour suppresser gene. [5]



What is tar?

“Tar”, also known as total particulate matter, is inhaled when the smoker draws on a lighted cigarette.  In its condensate form, tar is the sticky brown substance which can stain smokers’ fingers and teeth yellow-brown.  All cigarettes produce tar but the brands differ in amounts.  The average tar yield of British cigarettes (as measured by a standard machine method by the Government Chemist) has declined from about 30mg per cigarette in the period 1955‑61 to 11mg today.  There have also been reductions in nicotine (from an average of about 2mg in 1955‑61 to about 0.9mg by 1996). [6] [7]