“…The advection-diffusion equation aims at representing the time behavior of the entire concentration field, while existing ARIMAX (as well as ARIMA) applications supply only a local or aggregate description of the pollution phenomenon. Precisely, they are univariate models, namely they aim at representing the dynamics of a single variable, either the concentration in a certain monitoring station or a spatial concentration average (the DAP or Dosage Area Product 11 ). An intermediate detail of description of the phenomenon of pollutant dispersion is given by the stochastic models illustrated in the present paper, together with their application to a real case (sulphur dioxide pollution in the heating season, in Milan, Italy).…”