In mountain areas as described in the study ‘Mountain areas in Europe: analysis of mountain areas in EU Member States, acceding and other European countries’ commissioned by the European Commission in 2004, higher external-cost charges should be permitted to the extent that objective scientific data prove that air and noise pollution cause greater damage in those mountain areas due to geographic circumstances and physical phenomena such as the gradient of roads, temperature inversions and the amphitheatre effect of valleys.
In berggebieden zoals beschreven in de, in opdracht van de Europese Commissie verrichte, studie „Mountain Areas in Europe: Analysis of mountain areas in EU Member States, acceding and other European countries” van 2004, kunnen hogere externekostenheffingen worden toegestaan voor zover wetenschappelijke gegevens aantonen dat luchtvervuiling en geluidhinder in berggebieden grotere schade veroorzaken ten gevolge van geografische omstandigheden en natuurkundige verschijnselen zoals het stijgingspercentage van de wegen, temperatuurinversies en amfitheatereffecten van valleien.