The particle, size distribution and particulate concentration of cigarette smoke has been measured using a centrifugal collection instrument called the "Conifuge." The instrument avoids the difficulty of direct size measurement by continuously grading the particles according to settling velocity or size. It is capable of collecting particles ranging in diameter between 0.05 and 10 microns. For these reasons the instrument is well suited for measurement of the size distribution of cigarette smoke and other aerosols. The size distribution and particulate concentration of smoke were found to be reproducible quantities for similar cigarettes, but were found to vary according to the age of the smoke sample, even after considerable dilution. The rate of decrease of the number concentration of smoke particles was found to agree reasonably well with the rate predicted by the modified Smoluchowski coagulation equation. Alteration of a number of smoking and cigarette variables was found to have no detectable effect on the particle size distribution, but changed the concentration of particles in a manner similar to the effect of these variables on the weight of smoke. A preferential removal of larger particles was observed for high­efficiency tobacco and cigarette filters, in addition to a considerable decrease in particulate concentration. The essentially constant size distribution appears to arise through the removal of small particles through coagulation and larger particles through filtration by the tobacco strands.

(Full article published with kind permission from "Tobacco International")