Based on the analysis of data on the volume of emission from 163 enterprises, a classification of industrial projects that are the sources of ambient air pollution has been developed, which includes: an estimate of the degree of hazard (5 classes) from enterprises by the total volume of emission irrespective industrial affiliation and the kind of activities; the relative index (RI) of hazard from an enterprise, which considers the volume of emission and the degree of toxicity of each pollutant (the RI specifies the class of an enterprise); the possible sizes of sanitary-hygiene zones in relation to the total volume of emission (tons per year). Testing the developed classification, by using 64 enterprises and various projects as an example has shown the expedisanitary-hygiene zones of an enterprise and projects of any branches of industry or the kind of activities, which are ambient air pollution sources.