The article highlights an environmental problem that is relevant for industrial cities, namely the identification of the source of excess emissions. The existing monitoring systems are not designed to identify sources that are violators, and the Supervisory authorities currently lack not only a tool, but also an algorithm for identifying the violator when determining excess pollution levels. The article considers current methods and devices aimed at locating a source that has allowed an excess emission, but all of them have their own disadvantages and limitations. The article presents a method for identifying the source of excess emission based on air sampling conducted by mobile laboratories. The proposed method was tested on mobile laboratory data obtained during an atmospheric air survey in the Soviet administrative district of Omsk. The results of the estimated emission power, determining the multiplicity of excess for each of the considered sources, and identifying the most likely source that allowed an excess emission are presented. Locations have also been identified for confirming windward and leeward sampling from the suspected offending source. The developed method is based on the use of a method approved in Russia for calculating the dispersion of pollutants, which makes it possible to use the results obtained by Supervisory environmental authorities as an evidence base for specific sources of pollution.