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" A lit cigarette is like a chemical factory, releasing poisonous fumes into your lungs and air. Only the tobacco companies know exactly what goes into each cigarette, and only some of this information is available. This means research is still underway to determine exactly what goes into a cigarette. So far more than 4000 different substances have been identified in cigarette smoke. Around half of these substances are found in the tobacco itself, the rest are produced as the tobacco burns. Studies are ongoing to determine which additives and ingredients in tobacco smoke are harmful. For example, health authorities in Canada have produced a list of 44 substances they consider to be particularly harmful:  ammonia carbon monoxide   nicotine nitric oxide hydrogen cyanide mercury  tar*  toxic trace metals (nickel*, lead, cadmium*, chromium*, arsenic* and selenium) tobacco-specific nitrosamines (TSNAs): N-nitrosonornicotine*, nicotine-derived nitrosamino ketone (NNK)*, N-nitrosoanatabine* and N-nitrosoanabasine*.  aromatic amines: 1-aminonapthalene, 2-aminonapthalene, 3-aminobiphenyl and 4-aminobiphenyl* benzo[a]pyrene*   volatile carbonyls (formaldehyde*, acetaldehyde*, acetone, acrolein, propionaldehyde, crotonaldehyde, methyl ethyl ketone and butyraidehyde) 10 selected basic semi-volatiles: pyridine and quinoline 11 phenolic compounds: hydroquinone, resorcinol, catechol, phenol, m+p-cresol, and o-cresol   13 selected volatiles: 1,3-butadiene*, isoprene, acrylonitrile*, benzene*, toluene and styrene.   *carcinogenic (cancer causing) How do these ingredients harm health?  Tobacco-specific nitrosamines (TSNAs) and tar are particularly carcinogenic, while carbon monoxide decreases the amount of oxygen in your blood. This means your heart has to work harder to pump blood around the body, raising your pulse and blood pressure, and can lead to shortness of breath. As well as being a carcinogen, tar condenses into a brown sticky substance that deposits in the lungs, transporting many other harmful chemicals from smoke in the process. Tar clogs up the small hairs (cilia) that protect and clean the lungs. Nicotine causes addiction, making it difficult to stop smoking and avoid the illnesses it causes. Even when faced with amputation if they don&amp;#039;t quit, some smokers cannot give up. Some studies say ammonia makes nicotine more addictive by increasing nicotine vapour in a cigarette to give a bigger &amp;#039;kick&amp;#039;. The tobacco industry has been accused of adding ammonia to cigarettes, but this is the subject of much disagreement because the natural ammonia content of various tobacco types differs, and ammonia is also a by-product when a cigarette is smoked.  Formaldehyde can cause cancer and damage to your skin, lungs, stomach and bowels. Hydrogen cyanide is one of the most toxic chemicals in cigarette smoke. It can cause headaches, nausea, dizziness and vomiting. Benzene can cause cancer, particularly leukaemia. Cadmium can cause brain, kidney and liver damage. Lead can cause damage to the brain, kidney and red blood cells.  Why are additives used?  Additives are used for a variety of purposes. For example, an absorbent substance such as glycerol is added to prevent the tobacco crumbling. Various salts are added to give the cigarette an even-burning quality, and additives are used in the paper. Flavours are used to give a brand of cigarette a particular taste. Menthol and eugenol (the aroma of cloves) are added because they act as a pain reducer on the mucous membranes of the throat, making cigarette smoke less irritating. Various flavours are added to give a better taste, for example cocoa, liquorice and sugar. Smoke harms non-smokers  While all tobacco smoke is bad for your health, there are two types of smoke. The smoke you inhale is called mainstream smoke, the smoke from the cigarette tip between puffs is called sidestream smoke. Mainstream and sidestream smoke have different chemical compositions: sidestream smoke contains a higher concentration of harmful substances. Almost 85 per cent of smoke in a room comes from sidestream smoke. Because smokers are exposed to both types of smoke, this doesn&amp;#039;t mean that passive smoking is more dangerous. But a non-smoker who lives in a smoky environment will have nicotine content in their blood as high as that of a moderate smoker, ie 10 a day. Is all tobacco equally dangerous? Tobacco is generally divided into two categories: &amp;#039;smoke-free&amp;#039; tobacco, such as snuff and chewing tobacco, and &amp;#039;smoking&amp;#039; tobacco, which includes cigarettes, pipe tobacco, cigars and cheroots. All these products create dependency and are harmful to health. &amp;#039;Mild&amp;#039; brands  Since September 2003 terms such as &amp;#039;low-tar&amp;#039;, &amp;#039;light&amp;#039; and &amp;#039;ultra light&amp;#039; have been banned. This is because the difference between these brands and regular cigarettes is dependent on the filter alone, which uses microscopic air holes: the &amp;#039;lighter&amp;#039; the cigarette, the more holes it has for drawing in air that thins and cools the smoke. However, the thinned smoke contains less nicotine. Smokers can, unwittingly or otherwise, solve the &amp;#039;problem&amp;#039; of reduced nicotine either by dragging harder on the cigarette or by grasping the filter and blocking the holes.  Research has shown that, contrary to the numbers on the packet, smokers of &amp;#039;mild&amp;#039; brands are likely to inhale as much tar and nicotine as smokers of regular cigarettes. And because the same blend of tobacco is used, you can take in as many cancer-causing substances. Cigars and pipes  A large cigar can contain 400 times more nicotine than a cigarette. However cigar smokers only inhale a small percentage of this, and it is quickly broken down.  Because cigar and pipe smokers who have never smoked cigarettes tend not to inhale, they are exposed to lower amounts of tar and other harmful substances in tobacco. While this means a lower risk of smoking-related illness than cigarette smokers, there is still a health impact. Regardless of how little you inhale, your mouth and throat are exposed to smoke, which dissolves into salvia and is swallowed. So cigar and pipe smokers face an increased risk of cancers of the mouth, throat and oesophagus. Cigar and pipe smokers also have an increased risk of lung cancer. This is partly from frequent exposure to sidestream smoke, which is greater from cigars than cigarettes, and raises even a non-smoker&amp;#039;s risk of lung cancer by 20 per cent. Cigar smoke also contains higher levels of cancer-causing TSNAs and tar. In all cases the risk of a smoking-related illness is substantially higher if pipe and cigar smokers are ex-smokers of cigarettes. Snuff and chewing tobacco Snuff and chewing tobacco are not widely used in the UK, but are relatively common in mainland Europe. Dried snuff is inhaled through the nose and moist snuff is placed between the lip and the gum. Smoke-free tobacco products don&amp;#039;t contain tar, but have a high nicotine content - 10 times as much as cigarettes. Because nicotine causes dependency, users of these products find it more difficult to stop. While smoke-free tobacco doesn&amp;#039;t cause lung damage, the carcinogenic substances produced in its manufacture increase the risk of mouth and throat cancer. Smoke-free tobacco also increases the risk of gum disease, and discolours and scratches teeth.  Based on a text by Sven Edelfors, biochemist  Last updated 27.08.2012 "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.netdoctor.co.uk/healthy-living/wellbeing/a5024/the-chemical-factory/>