Variable gases

Table 1 gives the concentration and residence time of atmospheric gases on the basis of the data of different authors. In the table the concentrations of quasipermanent and variable gases are expressed partly in parts per hundred (percent by volume) and partly in parts per million (ppm). In the case of some highly variable gases the concentrations are also expressed in /ig/m3 STP because these units are widely used in atmospheric chemical measurements. (For the conversion of ppm concentrations into /tg/m3 values see Table 4, p. 30). 

Again, just as the fixed gases are present in nearly every material present on the Earth s surface, variable gases are also present in all materials that are porous and can be found on the surfaces of many other materials. 

Tobacco contains all of the fixed gases that are present in the atmosphere. It also contains a variety of variable gases... 

The concentration of the fixed and variable gases in tobacco smoke is not directly related to the concentration of these gases in tobacco. As tobacco smoke is the result of combustion and pyrolysis of tobacco, the concentration and types of fixed and variable gases formed vary considerably. 

Volume Percentages of Some Variable Gases (Inorganic and Organic) in the Atmosphere (19A04)... 

Ishiguru and Sugawara in 1980 (1884) cataloged the components of tobacco smoke. In their review, they listed 1889 components of tobacco smoke [see Table 1 in (1884)]. They commented that the number could be about 2500 but they had omitted those components that were only partially identified. Among the components that they discussed were the fixed and variable gases in tobacco smoke. 

In 1996, Green and Rodgman (1373) summarized all the historical and currently used analytical methods for the identification of chemicals isolated from tobacco and tobacco smoke. Their review is so complete and so well documented that the reader is directed to read their review article to determine the analytical method best suited for the analysis of a particular chemical constituent in tobacco and smoke. All of the past and current methods for the determination of fixed and variable gases in tobacco and tobacco smoke can be found in their article and will not be included in this chapter. Only a few specific examples of analytical methods for the most important variable gases will be provided (1884). 

Major Fixed and Variable Gases in Non-Filtered Whole Tobacco Smoke... 

Table XIX-5 is a catalog of the fixed and variable gases in tobacco, tobacco smoke, and tobacco substitute smoke. The catalog contains only thirty-five entries. This number of entries represents a very small fraction of the total number of identified components in tobacco and tobacco smoke but amazingly the weight contributed by fixed and variable gases represents about 90% of the whole smoke from a cigarette.

Eixed and Variable Gases in Tobacco, Tobacco Smoke, and Tobacco Substitute Smoke... 

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