SS. However, it does reflect specific trapping systems and analytic methods that have been developed for the standardized determination of individual components or groups of components in MS or SS (Brunnemann and Hoffmann, 1982; Dube and Greene, 1982).
Standardized machine-smoking conditions do not exactly duplicate the smoking patterns of an individual, which depend on many factors. For example, low nicotine delivery in cigarette smoke generally induces a smoker to puff more frequently (up to 5 puffs/minute), to draw larger volumes (up to 55 ml/puff), and to inhale more deeply. Puffing more frequently increases the amount of tobacco consumed during generation of MS and thus diminishes the amount of tobacco burned between puffs. This, in turn, affects the release of combustion products in SS, so an increase in puff frequency diminishes the production of SS and ETS. Also, smoking behavior appears to depend strongly on the blood concentration of nicotine that the smoker desires to reach (Krasnegor, 1979; Grabowski and Bell, 1983).
The smoker, because of proximity to the source, usually inhales more of the SS and ETS originating from the burning of the tobacco product than a nonsmoker; however, we do not know the exact amount and we do not know the degree to which inhaled SS and ETS aerosols are retained in the smoker’s respiratory tract. Model studies with MS have shown that more than 90% of some hydrophilic volatile components (e.g., acetaldehyde) is retained after inhalation by the smoker (Dalham et al., 1968a). Therefore, one may assume that a large proportion of the hydrophilic agents in the vapor phase of SS and ETS is also retained when smoke-polluted ambient air is inhaled. In the case of hydrophobic components of the vapor phase of MS (e.g., carbon monoxide), the retained fraction depends on the depth of inhalation, but it hardly ever exceeds 50% (Dalham et al., 1968b). An active smoker generally retains 90% or more of MS particles (Dalham et al., 1968b; Hiller, 1984), whereas a nonsmoker exposed to ETS appears to retain a smaller percentage of ETS particles. It has been calculated that, depending on the degree of SS pollution, a nonsmoker exposed to ETS can retain 0.014 to 1.6 mg of particles per day from ETS (Hiller, 1984).