Cigarette smoke

Tobacco smoke is an aerosol produced by the incomplete combustion of tobacco during the smoking of cigarettes, Smoking pipes, or cigars. Temperatures in burning cigarettes range from about 400 ℃ between puffs to about 900 ℃ during a puff. During the burning of tobacco (itself a complex mixture), thousands of chemical substances are generated by combustion, distillation, pyrolysis, and pyrosynthesis. Tobacco smoke is used as a fumigant and inhalant.

The particles in tobacco smoke are liquid aerosol droplets (~ 20% water), with a mass median aerodynamic diameter (MMAD) that is submicrometer (and thus, fairly "lung-respirable" by humans). The droplets are present in high concentrations (some estimates are as high as 10¹⁰ droplets per cm³). Most cigarettes today contain a cigarette filter, which can reduce "tar" and nicotine smoke yields up to 50% by several different mechanisms, with an even greater removal rate for other classes of compounds (e.g., phenols).

Tobacco smoke may be grouped into a particulate phase (trapped on a glass-fiber pad, and termed "TPM" (total particulate matter)) and a gas/vapor phase (which passes through such a glass-fiber pad). "Tar" is mathematically determined by subtracting the weight of the nicotine and water from the TPM. However, several components of tobacco smoke (e.g., hydrogen cyanide, formaldehyde, phenanthrene, and pyrene) do not fit neatly into this rather arbitrary classification, because they are distributed among the solid, liquid and gaseous phases.

Tobacco smoke contains a number of toxicologically significant chemicals and groups of chemicals, including polycyclic aromatic hydrocarbons (benzopyrene), tobacco-specific nitrosamines (NNK, NNN), aldehydes (acrolein, formaldehyde), carbon monoxide, hydrogen cyanide, nitrogen oxides, benzene, toluene, phenols (phenol, cresol), and aromatic amines (nicotine, ABP (4-Aminobiphenyl)). The radioactive element polonium-210 is also known to occur in tobacco smoke. The chemical composition of smoke depends on puff frequency, intensity, volume, and duration at different stages of cigarette consumption.

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