 double reaction and filtration system to lower the concentrations of particulate, hydrochloric acid, hydrofluoric acid, sulphur dioxide, heavy metals, dioxins and furans and aromatic polycyclic hydrocarbons (the Modena plant has a bag filter and an electrostatic precipitator);  double reaction system (catalytic and non-catalytic) to reduce concentrations of nitrogen oxides;  double fume monitoring system for process control: the two systems measure the concentrations of the main pollutants emanating from the oven and downstream of the first reaction and filtration phase, on the basis of which a calculation is made of the volume of reactants required to ensure treatment levels that guarantee respect for legal emission limits and which are, on average,  continuous double monitoring system for chimney emissions: one as a reserve for the other in order to guarantee the continuity of the analysis of concentrations in atmospheric emissions.