Additives are used to make tobacco products more acceptable to the consumer. While some of these may appear to be quite harmless in their natural form they may be toxic in combination with other substances. Also when additives are burned, new products of combustion are formed and these may be toxic. The nicotine and tar delivery can also be modified by the type of paper used in the cigarette. Filters are made of cellulose acetate and trap some of the tar and smoke particles from the inhaled smoke.
Filters also cool the smoke slightly, making it easier to inhale.
They were added to cigarettes in the 1950s, in response to the first reports that smoking was hazardous to health. Tobacco companies claimed that their filtered brands had lower tar than others and encouraged consumers to believe that they were safer. 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. The gas phase includes carbon monoxide, ammonia, dimethylnitrosamine, formaldehyde, hydrogen cyanide and acrolein.