Cigarette smoke is made up of both a gas phase and particulate phase.
Together they include more than 4,000 substances.
Automatic cigarette-puffing machines have been devised to collect and to study smoke.
The smoke is separated into the gas and solid (particulate) phases by passing it through a filter pad (Cambridge filter), which traps particles larger than one micrometre.
And collects the rest (gas phase) in a storage tank.
The machines are calibrated to smoke the cigarettes the way a typical smoker might smoke them.
During a puff, the un-burned cigarette is comprised of many organic components (tobacco leaves, paper products, sugars, nicotine) and inorganic (water, radioactive elements, metals) materials.
The tip of the burn-in cone in the centre of the cigarette reaches a temperature of nearly 1,093 degrees C.
(2,000 degrees F.
) during each puff.
This tiny blast furnace results in a miniature chemical plant, which uses the hundreds of available materials to produce many more.
In fact, some of the most important parts of tobacco smoke (including tar and carbon monoxide) are not even present in an unburned cigarette, but are produced when a puff is taken and the cigarette burns.
Study of the smoke is made even more complicated since there are both side stream and mainstream smoke which must be separately collected and studied.
The mainstream smoke is collected from the stream of air passing through the centre of the cigarette.
It is filtered by the tobacco itself and perhaps further by a filter.
It is also diluted by air passing through the paper (most modern cigarettes also have tiny ventilation holes which further dilute the smoke).
Side stream smoke is that which escapes from the tip of the cigarette.
It is not filtered by the cigarette and results from a slightly cooler burning process at the edge of the burning cone.
Since the tobacco is therefore burned less completely, the side stream smoke has more particulate (unburned material) in it.
Cigarette Engineering The above process is complicated even further by the engineering efforts of the tobacco manufacturers.
They specifically construct cigarettes in ways to control a wide range of factors: keeping the cigarette burning between puffs, reducing spoilage of the tobacco, altering the flavor of the smoke, and controlling the amounts of substances (tar and nicotine) measured by government agencies.
The porosity of cigarette paper is specifically controlled to regulate the amount of air that passes through and dilutes the smoke.
Porosity also affects how rapidly the cigarette burns.
Phosphates are added to the paper to ensure steady and even burning.
Several kinds of additives are present in the tobacco itself.
One type of additive is called humectants.
Humectants are chemicals that help retain the moisture (humidity) of the tobacco.
This is important in how the tobacco burns.
Humectants also affect the taste and temperature of the smoke.
The most commonly used humectants are glycerol, D-sorbitol, and diethylene glycol.
Humectants comprise a new per cent of the total weight of the tobacco.
Another type of additive is called a casing agent.
This helps blend the tobacco and hold it together.
It also affects the flavor of the smoke and how quickly the tobacco burns.
Most commonly used casing agents include sugars, syrups, licorice, and balsams.
The amount of casing agents used ranges from about 5% of the total weight of the tobacco in cigarette tobacco to about 30% of the weight of pipe tobacco.
Specific flavoring agents are also added to the tobacco to control the characteristic taste of a cigarette.
These include fruit extracts, menthol oils, spices, coca, aromatic materials, and synthetic additives.
Flavor is also controlled by curing processes and, of course, the type of tobacco itself.
A variety of other substances are added at various stages of tobacco processing to retard spoilage.
In addition, metals such as nickel and potassium are taken up from the soil, as are pesticides and fertilizers used in tobacco farming.
There are also radioactive elements such as potassium-40, lead-210, and radium-226, which result from fallout and the natural background.
Together they include more than 4,000 substances.
Automatic cigarette-puffing machines have been devised to collect and to study smoke.
The smoke is separated into the gas and solid (particulate) phases by passing it through a filter pad (Cambridge filter), which traps particles larger than one micrometre.
And collects the rest (gas phase) in a storage tank.
The machines are calibrated to smoke the cigarettes the way a typical smoker might smoke them.
During a puff, the un-burned cigarette is comprised of many organic components (tobacco leaves, paper products, sugars, nicotine) and inorganic (water, radioactive elements, metals) materials.
The tip of the burn-in cone in the centre of the cigarette reaches a temperature of nearly 1,093 degrees C.
(2,000 degrees F.
) during each puff.
This tiny blast furnace results in a miniature chemical plant, which uses the hundreds of available materials to produce many more.
In fact, some of the most important parts of tobacco smoke (including tar and carbon monoxide) are not even present in an unburned cigarette, but are produced when a puff is taken and the cigarette burns.
Study of the smoke is made even more complicated since there are both side stream and mainstream smoke which must be separately collected and studied.
The mainstream smoke is collected from the stream of air passing through the centre of the cigarette.
It is filtered by the tobacco itself and perhaps further by a filter.
It is also diluted by air passing through the paper (most modern cigarettes also have tiny ventilation holes which further dilute the smoke).
Side stream smoke is that which escapes from the tip of the cigarette.
It is not filtered by the cigarette and results from a slightly cooler burning process at the edge of the burning cone.
Since the tobacco is therefore burned less completely, the side stream smoke has more particulate (unburned material) in it.
Cigarette Engineering The above process is complicated even further by the engineering efforts of the tobacco manufacturers.
They specifically construct cigarettes in ways to control a wide range of factors: keeping the cigarette burning between puffs, reducing spoilage of the tobacco, altering the flavor of the smoke, and controlling the amounts of substances (tar and nicotine) measured by government agencies.
The porosity of cigarette paper is specifically controlled to regulate the amount of air that passes through and dilutes the smoke.
Porosity also affects how rapidly the cigarette burns.
Phosphates are added to the paper to ensure steady and even burning.
Several kinds of additives are present in the tobacco itself.
One type of additive is called humectants.
Humectants are chemicals that help retain the moisture (humidity) of the tobacco.
This is important in how the tobacco burns.
Humectants also affect the taste and temperature of the smoke.
The most commonly used humectants are glycerol, D-sorbitol, and diethylene glycol.
Humectants comprise a new per cent of the total weight of the tobacco.
Another type of additive is called a casing agent.
This helps blend the tobacco and hold it together.
It also affects the flavor of the smoke and how quickly the tobacco burns.
Most commonly used casing agents include sugars, syrups, licorice, and balsams.
The amount of casing agents used ranges from about 5% of the total weight of the tobacco in cigarette tobacco to about 30% of the weight of pipe tobacco.
Specific flavoring agents are also added to the tobacco to control the characteristic taste of a cigarette.
These include fruit extracts, menthol oils, spices, coca, aromatic materials, and synthetic additives.
Flavor is also controlled by curing processes and, of course, the type of tobacco itself.
A variety of other substances are added at various stages of tobacco processing to retard spoilage.
In addition, metals such as nickel and potassium are taken up from the soil, as are pesticides and fertilizers used in tobacco farming.
There are also radioactive elements such as potassium-40, lead-210, and radium-226, which result from fallout and the natural background.