According to the European Seveso III Directive, Member States should ensure that their land-use policy aims at maintaining appropriate safety distances between Seveso establishments and areas with high population densities. In Flanders, the location specific and societal risk of (upper-tier) Seveso establishments are calculated and evaluated against strict criteria when changes to the activities and/or the installations with dangerous substances within the Seveso establishment are planned. However, when new land developments that increase the off-site population are planned, the societal risk is often not recalculated. As a result of this and because of the difficulty (if not impossibility) to assess the impact of an increase in population on the societal risk without additional calculations, such off-site developments could unknowingly result in an exceedance of the societal risk criteria.
In order to aid land-use planners and the authorities in the evaluation of new developments in the vicinity of a Seveso establishment, a quick scan method has been developed to assess the impact of an increased population on the societal risk posed by the Seveso establishment. Restrictions that apply to the increase of population in the surroundings of the establishment can also be visualised on a map. In this paper this method is described, together with some worked-out examples.