Twenty years of Belgian North Sea aerial surveillance: A quantitative analysis of results confirms effectiveness of international oil pollution legislation

► Effectiveness of international regulations on ship-source oil pollution. ► MARPOL Special Area and EU Directive on Port Reception Facilities are key measures. ► There is a stepwise decrease in operational oil pollution over the last 20 years. ► Turning points coincide with the actual implementation of these key measures. ► Minor slicks still lead to chronic oil pollution with important environmental impact.