Cigarettes

Cigarette is a product consumed through smoking and manufactured out of cured and finely cut tobacco leaves and reconstituted tobacco, often combined with other additives, then rolled or stuffed into a paper-wrapped cylinder (generally less than 120 mm in length and 10 mm in diameter). The cigarette is ignited at one end and allowed to smoulder for the purpose of inhalation of its smoke from the other (usually filtered) end, which is inserted in the mouth. They are sometimes smoked with a cigarette holder. The term cigarette, as commonly used, refers to a tobacco cigarette but can apply to similar devices containing other herbs, such as cannabis.
Nicotine, the primary psychoactive chemical in tobacco, is addictive. Cigarette use has also been shown to cause multiple types of cancer, heart disease, respiratory disease, circulatory disease, birth defects (which include mental and physical disability) and emphysema.
Rates of cigarette smoking vary widely. While rates of smoking have leveled off or declined in the developed world, they continue to rise in the undeveloped world.
A cigarette is distinguished from a cigar by its smaller size, use of processed leaf, and white paper wrapping. Cigars are typically composed entirely of whole-leaf tobacco.

Manufacturing
Commercially manufactured cigarettes are seemingly simple objects consisting mainly of a tobacco blend, paper, PVA glue to bond the outer layer of paper together, and often also a cellulose acetate–based filter.While the assembly of cigarettes is straightforward, much focus is given to the creation of each of the components, in particular the tobacco blend, which may contain over 100 ingredients, many of them flavourants for the tobacco. A key ingredient that makes cigarettes more addictive is the inclusion of reconstituted tobacco, which has additives to make nicotine more volatile as the cigarette burns.

Paper
Main article: Cigarette paper
The paper for holding the tobacco blend may vary in porosity to allow ventilation of the burning ember or contain materials that control the burning rate of the cigarette and stability of the produced ash. The papers used in tipping the cigarette (forming the mouthpiece) and surrounding the filter stabilise the mouthpiece from saliva and moderate the burning of the cigarette as well as the delivery of smoke with the presence of one or two rows of small laser-drilled air holes.
The burn rate of cigarette paper is regulated through the application of different forms of microcrystalline cellulose to the paper. Cigarette paper has been specially engineered by creating bands of different porosity to create "fire-safe" cigarettes. These cigarettes have a reduced idle burning speed which allows them to self-extinguish. This fire-safe paper is manufactured by mechanically altering the setting of the paper slurry.
New York was the first U.S. state to mandate that all cigarettes manufactured or sold within the state comply with a fire-safe standard. Canada has passed a similar nation-wide mandate based on the same standard. Many other U.S. states have passed or are considering fire-safe mandates.

Tobacco blend
The tobacco part viewed from a cigarette
The process of blending, like the blending of scotch and cognac, gives the end product a consistent taste from batches of tobacco grown in different areas of a country that may change in flavour profile from year to year due to different environmental conditions.
Modern cigarettes produced after the 1950s, although composed mainly of shredded tobacco leaf, use a significant quantity of tobacco processing by-products in the blend. Each cigarette's tobacco blend is made mainly from the leaves of flue-cured brightleaf, burley tobacco, and oriental tobacco. These leaves are selected, processed, and aged prior to blending and filling. The processing of brightleaf and burley tobaccos for tobacco leaf "strips" produces several by-products such as leaf stems, tobacco dust, and tobacco leaf pieces ("small laminate"). To improve the economics of producing cigarettes, these by-products are processed separately into forms where they can then be possibly added back into the cigarette blend without an apparent or marked change in the cigarette's quality. The most common tobacco by-products include:
Blended leaf (BL) sheet: a thin, dry sheet cast from a paste made with tobacco dust collected from tobacco stemming, finely milled burley-leaf stem, and pectin.
Reconstituted leaf (RL) sheet: a paper-like material made from recycled tobacco fines, tobacco stems and "class tobacco", which consists of tobacco particles less than 30 mesh in size (~0.599 mm) that are collected at any stage of tobacco processing. RL is made by extracting the soluble chemicals in the tobacco by-products, processing the leftover tobacco fibres from the extraction into a paper, and then reapplying the extracted materials in concentrated form onto the paper in a fashion similar to what is done in paper sizing. At this stage ammonium additives are applied to make reconstituted tobacco an effective nicotine delivery system.
Expanded (ES) or improved stems (IS): ES are rolled, flattened, and shredded leaf stems that are expanded by being soaked in water and rapidly heated. Improved stems follow the same process but are simply steamed after shredding. Both products are then dried. These two products look similar in appearance but are different in taste.
Whole tobacco can also be processed into a product called expanded tobacco. The tobacco is "puffed", or expanded, by saturating it with supercritical carbon dioxide and heating the CO2 saturated tobacco to quickly evaporate the CO2. This quick change of physical state by the CO2 causes the tobacco to expand in a similar fashion as polystyrene foam. This is used to produce light cigarettes ("Lights") by reducing the density of the tobacco and thus maintain the size of a cigarette while reducing the amount of tobacco used in each cigarette.
A recipe-specified combination of brightleaf, burley-leaf and oriental-leaf tobacco will be mixed with humectants such as propylene glycol or glycerol, as well as flavouring products and enhancers such as cocoa, licorice, tobacco extracts, and various sugars, which are known collectively as "casings". The leaf tobacco will then be shredded, along with a specified amount of small laminate, expanded tobacco, BL, RL, ES and IS. A perfume-like flavour/fragrance, called the "topping" or "toppings", which is most often formulated by flavor companies, will then be blended into the tobacco mixture to improve the consistency in flavour and taste of the cigarettes associated with a certain brand name. As well, they replace lost flavours due to the repeated wetting and drying used in processing the tobacco. Finally the tobacco mixture will be filled into cigarettes tubes and packaged.
In recent years, the manufacturers' pursuit of maximum profits has led to the practice of using not just the leaves, but also recycled tobacco offal and the plant stem. The stem is first crushed and cut to resemble the leaf before being merged or blended into the cut leaf.

Cigarette litter
A cigarette disposal canister, encouraging the public to dispose of their cigarettes properly.
Cigarette filters are made from cellulose acetate and is biodegradable, however depending on environmental conditions it can be resistant to degradation. Accordingly, the duration of the degradation process is cited as taking al little as 1 month to 3 years to as long as 10-15 years.
This variance in rate and resistance to biodegradation in many conditions is a factor in littering andenvironmental damage. It is estimated that 4.5 trillion cigarette butts become litter every year. In the 2006 International Coastal Cleanup, cigarettes and cigarette butts constituted 24.7% of the total collected garbage, over twice as much as any other category.
Cigarette butts contain the chemicals filtered from cigarettes and can leach into waterways and water supplies.
Cellulose acetate and carbon particles breathed in from cigarette filters is suspected of causing lung damage.

Cigarette advertising
In many parts of the world tobacco advertising and even sponsorship of sporting events has been outlawed. The ban on tobacco advertising and sponsorship in the EU in 2005 has prompted Formula One Management to look for races in areas that allow the tobacco sponsored teams to display their livery. As of 2007, only the Scuderia Ferrari retains tobacco sponsorship, continuing their relationship with Marlboro until 2011.
In some jurisdictions, such as Saskatchewan, Canada, the retail store display of cigarettes is completely prohibited if persons under the legal age of consumption have access to the premises