Megapolis area comprises a zone of interaction of a great number of anthropogenic factors that shall be considered while defining quality of environmental conditions, and first of all while identifying sources of pollution. One of essentially important tasks is to identify local sources of pollution at general background. These sources have not made their considerable contribution to overall condition of the territory yet, but, nevertheless, they are potentially hazardous in the future. The authors consider methods for handling the information on pollution of similar local areas and specifics of recording such a varied information.