The paper presents a comparative analysis of the accuracy characteristics of different types of photoelectric counters (PEC's). Their basic applicability limits have been analyzed. In this case primary emphasis is placed on the elimination of errors caused by the physical nature of particles. It is shown that this factor can be eliminated using interferometric counters of aerosol particles, in particular, those using radiation at different wavelengths. The paper describes the basic relations determining the metrological characteristics of such counters.