Characteristics of Airborne Particles

Airborne particulates are primarily responsible for the visible effects of air pollution and contribute appreciably to the total mass of pollutants. A substantial fraction of the particulates is submicroscopic so optical methods are not suitable for following their life history. Techniques for measuring number and average size of submicroscopic particles over wide ranges have been developed but are not widely known or used outside the laboratory. A review is given here of some of the more useful parameters of particles and methods by which these can be measured.