A review of the influence of particle size, puff volume, and inhalation pattern on the deposition of cigarette smoke particles in the respiratory tract.

Ventilation of the cigarette was designed to allow dilution of the cigarette smoke and thereby reduce the dose delivered to the smoker. Following the toxicological principle of dose response, a lower concentration of cigarette smoke should be associated with a lower toxicological response. However, there have been many studies reporting on the phenomenon of compensation whereby the smoker increases puff volume and/or frequency in order to obtain higher volumes of smoke This article reviews studies of the particle size of cigarette smoke and examines, based on available literature, the associated differences in the tobacco smoke and smoking behavior and their relationship to deposition patterns in the lung. The data available indicate that particle size of the cigarette smoke does not significantly change as a function of cigarette type or smoking behavior. The cigarette smoke particle size is in the same range as the minimum deposition particle size in the lung. While varying concentrations of particles are taken into the mouth, the subsequent inhalation pattern has been reported as remaining constant and also does not appear to change significantly under different smoking types and conditions. The dynamics of what happens to the smoke in the short time it is retained in the mouth have not been studied, and this perhaps should be the subject of future investigations. The current data therefore suggest that the particle deposition pattern of the smoke within the lung would not change significantly if compensation occurs.