We discuss the predictability of anti-cyclonic weather conditions that inhibit the dis- persion of pollutants, by means of a numerical weather prediction model (ALADIN). The aim is to get a practical procedure that can be applied by an operational service rather than to gain insight in the mechanism of the dispersion itself. We investigated some meteorological parameters and compared them to the concentrations of some pollutants (NO,NO2,PM10) measured in the region of Brussels during two years. We concluded that for an operational application it is sufficient and advisable to con- sider the presence of inversions and wind speed onldy.