Determination of Particle-Size Distribution and Concentration of Cigarette Smoke by a Light-Scattering Method

A new method for determining particle-size distribution of cigarette smoke particles was developed by simultaneous measurement of scattered light at three angles for a fixed wavelength. A theoretical chart useful for this purpose, which was made of the relative intensities of scattered light at the angles 45° and 135° to that at the angle 90°, was calculated on the basis of the Mie theory. The number concentration was determined from the Rayleigh ratio using the working standard method. The measurements were rapidly performed, without change of particle size during measuring time, with a device for dilution. The geometric mean diameter, the logarithmic standard deviation and the number concentration of mainstream smoke were found to be about 0.18 um, 0.4 and 3 X 10¹⁰ particles per cubic centimeter, respectively. Although the particle size presented here is smaller and the number concentration is higher than many of the previous results, the particle size is in good agreement with a few results which are considered to be more accurate. Further, the geometric mean diameter and logarithmic standard deviation of sidestream smoke .were found to be about 0.1 um and 0.4, respectively. Some previous papers have indicated that alteration of smoking conditions, tobacco type, etc. had no detectable effects on particle size; however, present work revealed a significant change in particle size and number concentration. The rapid measurement of diluted smoke by our new method seems to detect the particle size dependence on smoking variables in detail.