By means of the dispersion quotient method, the aerosol properties of freshly produced sidestream smoke were measured during the puff and subsequent interpuff period. These measurements were made on short time scales and at high aerosol concentrations. Examples are presented, which show the influence of different combustion conditions during the puff (resulting from different degrees of ventilation and different types of tobacco) on the emission of sidestream particles during the interpuff period. The ratio of the volume concentrations of the particles before and during a puff is reduced by ventilation and is nearly unchanged by the variation of the tobacco type.