The modern development of the industry, new technologies and a lot of harmful substances more than 2500 names attracts a lot of attention to industrial ventilation systems. The subject of this paper is analysis and generalization of foreign experience within the limits of proposed theory. In this paper, as a continuation of the previous papers the basics of designing effective industrial ventilation systems by optimizing air flow were described. An integrated exponential power dependence for defining the recovery effectiveness of different harmful substances by different local exhaust devices was proposed. The conception of equivalent effective velocity was proposed and substantiated. The method of optimal air exchange calculation and engineering design techniques were proposed.