Application of the phenomena of particle growth by condensation to industrial dust collection was studied. The analysis to evaluate the extent of size enlargement was first introduced to the two essential and industrially useful methods, one of which is the mixing of hot saturated air with cold air, the other being injection of steam into air. Four typical processes are proposed for effective application to industrial exhaust gas and the procedure of using these processes is illustrated according to the various conditions of exhaust gas. The technique for size enlargement of aerosol particles by condensation was found to be essentially applicable to any industrial exhaust gas which contains submicron dust particles in low number concentration when the appropriate process shown herein is selected.