What emission scenarios of the facility undergoing HIA must be evaluated?

The emission scenarios to be evaluated, in the case of a modification of an existing plant, are those related to the actual ante operam operation (i.e., existing before the implementation of the design modification subjected to an EIA) and the predicted post operam operation. Sometimes the scenario referring to the IPPC (Integrated Pollution Prevention and Control) permit emission values is considered as ante operam configuration, which, however, almost never corresponds to the actual operation of the plant. In the case of a new plant, a comparison between ante and post operam scenarios will not be possible, and the assessment will concern the additional contribution of the plant on the existing situation on the territory.