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To evaluate the actual exposure level of nonsmokers to environmental tobacco smoke (ETS) in their daily life, the exposure level of ambient nicotine was measured with a nicotine personal monitor carried by a nonsmoker. Average exposure levels of nicotine, even in such smoky places as cars, coffee shops and pubs, were less than 45 micrograms/m3. As a result of all-day monitoring, the highest amount of nicotine inhaled in a day was estimated, in this study, to be up to 310 micrograms, equivalent to actively smoking 0.31 ordinary cigarettes.

The values of effective thermal conductivity, specific heat and thermal diffusivity of various kinds of tobacco shreds, which are necessary for the solution of heat transfer problems of a smouldering cigarette, were determined. Effective thermal conductivity of tobacco shred packed into simulated cigarette columns was measured by a transient hot-wire method as a function of packing fraction at conditions of 20°C and 60 % relative humidity. Specific heat was measured with the aid of a differential scanning calorimeter (DSC). The thermal diffusivity was obtained from the values of effective thermal conductivity, specific heat and packing density. Effective thermal conductivity increased with increasing packing fraction (1 - e) and was uniformly expressed as a function of the total void fraction (et) inside the column regardless of tobacco types and stalk positions, whereas thermal diffusivity decreased with the packing fraction. At the same packing fraction, bright shreds produced higher values of effective thermal conductivity as well as higher specific heats (although specific heat was independent of the packing fraction) but had lower thermal diffusivity values than Burley and Matsukawa shreds.

In this paper, thermal analyses (thermogravimetry, TG: derivative thermogravimetry, DTG: differential scanning calorimetry, DSC) of the tobacco char left after pyrolysis of tobacco shreds were carried out in a nitrogen atmosphere containing given amounts of oxygen under a linear heating or an isothermal condition. The principal object of the present work is to obtain apparent kinetic parameters useful in predicting the overall rate of the tobacco char - oxygen reaction. The TG-DTG-DSC curves obtained under linear heating conditions showed that the oxidation process of the tobacco char apparently consisted of two main steps ( I and II), which were independent of each other. Assuming that a uniform reaction model based on reaction rate - determined processes could be applied to the tobacco char - oxygen reactions in both steps, the oxidation rates for both steps were determined. The results showed that the oxidation rates of both steps could be expressed as:The values of activation energies, E, and pre-exponential factors, Z, for the oxidation reactions in steps I and II were found to be 19-21, 33-40 kcal/mol and 5.9 × 10NomenclatureAs reactant (solid phase, tobacco char)E activation energy [kcal molpo2,∞ ambient oxygen partial pressure [atm, 1 atm = 1.013 × 10R gas constant [ 1.98 cal molT temperature [K]t time [min]W weight loss of tobacco char up to time, t, or temperature, T [mg]Wc weight loss of tobacco char at completion of reaction [mg]Z pre-exponential factor [mina fraction of As decomposed at time, t, defined by a = W/W