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Wednesday, February 22, 2012

What's in a cigarette?

Modern cigarette manufacturing is a sophisticated, complex industry in which manufacturers compete to satisfy the demands and preferences of consumers. As cigarette use spread, the cultivation of tobacco gained in popularity. At first, all cigarettes were rolled manually, whether by the individual smoker or by shop workers, who rolled and glued cigarettes before they were packaged.

Cigarette Structure
Cigarette applications
TOBACCO
Only a portion of the tobacco inside a cigarette comes from the leaf of a tobacco plant. A significant amount of the shredded brown innards of most modern cigarettes is a paper product called "reconstituted tobacco" or "homogenized sheet tobacco," which is made from a pulp of mashed tobacco stems and other parts of the tobacco leaf that would otherwise go to waste.

In addition to reconstituted tobacco, cigarette companies pack cigarettes with so-called puffed tobacco (also called "expanded tobacco"), which allows them to produce more cigarettes per pound of tobacco grown with lower levels of tar particles in the smoke.
PAPER WRAP
Though seemingly innocuous, cigarette paper is largely responsible for the rate at which a cigarette burns and the amount and density of the smoke it produces. The paper displays a pattern of concentric circle striations called "burn rings." The burn rings correspond to two different thicknesses in the paper, which serve to precisely control the speed at which the cigarette burns, slowing it automatically when the smoker is not inhaling in order to prolong the cigarette's consumption and speeding it up as the smoker takes a drag so as to maximize smoke intake.

FILTER

The filter cigarette was a specialty item until 1954, when manufacturers introduced it broadly following a spate of speculative announcements from doctors and researchers concerning a possible link between lung diseases and smoking. Reacting to smokers' voiced fears and sudden reduced cigarette consumption, cigarette companies, by altering the filter's structure and materials, began making competing claims about how low their brands' tar and nicotine levels were.
Some cigarettes today boast the inclusion of a "charcoal filter" in addition to the more common dense, synthetic fiber filters seen in almost all filter cigarettes. Manufacturers claim that charcoal filters in cigarettes, which contain bits of charcoal embedded within the fiber filters, reduce certain toxins in the smoke.
Most filter cigarettes also bear ventilation holes punched around the circumference of the filter tip. (Regular cigarettes might feature one ring of ventilation holes, while light and ultra-light cigarettes of the same brand might have two or more rings.) These tiny holes, which you can see by holding the unrolled paper up to a bright light, can allow enough fresh air into the smoke that such cigarettes can test quite low in tar and nicotine levels when smoked by machines, which do not cover the holes. However, smokers' fingers or lips often cover some of these holes as they puff, giving them much higher doses of tar and nicotine than advertised. According to critics of the tobacco industry, the holes create a flexible dosing system that allows addicted smokers to maintain the tar and nicotine levels they crave while believing they are receiving lower, safer doses.

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