Particle Size Distributions
Warren H. Finlay, Chantal Darquenne
Abstract
The distribution of particles sizes within an aerosol is essential information for understanding the behavior of that aerosol. The number of particles within certain size ranges is given by distributions specified by a count distribution if referring to number of particles, or a mass distribution if referring to particle mass. The cumulative number, or mass, of particles less than a certain diameter is determined by integrating the relevant distribution, which allows definition of median diameters. The mass median diameter is a commonly specified diameter. For log-normal distributions, the spread of the distribution is given by the geometric standard deviation. Although particle size distributions of actual aerosols are discrete by nature, the use of continuous functions to describe them is a useful conceptual tool.