Impact of a European directive on ship emissions on air quality in Mediterranean harbours

► Observations in Mediterranean harbours show impact of EU directive 2005/33/EC on SO2. ► Statistically significant lower SO2 levels were found in 3 out of the 4 EU harbours. ► SO2 did not change in non-EU harbour. ► The average decrease of the daily means was 66%. ► Neither NOx nor BC changed significantly.