Several industrial hot spots exist in Bulgaria and detail study of every one is worth to be done, but often incidents with high pollution levels over usually relatively clean populated areas cause big political concern. Stara Zagora is one of the biggest towns in Bulgaria (300 000 inhabitants) located in the middle of the country. In the summer of 2004, two high level
pollution events happened causing big public complains and even political and judicial consequences. Analogous events happened in 2005, too. All this requires appropriate measures to be taken by local authorities, first of all a suitable monitoring and forecasting system to be set. For the moment such system does not exist; only ambient air concentrations are measured in several points. This is not sufficient neither to predict nor even to explain the cases. As far as the mathematical modeling is alternative and supplementing tool according to the EU Framework Directive on Air Quality (96/62/ES) and its daughter directives (see, [5,6,7,16]), an attempt to simulate one of these events was done applying one of the most comprehensive and up-to-science modeling tools, mainly the US EPA Model-3 system.