Air pollution from ships in three Danish ports

The operational meteorological air quality model (OML) was used to calculate the urban dispersion of air pollutants originating from ships in three Danish ports: Copenhagen, Elsinore and Køge. Oxides of nitrogen (NOx=NO+NO2) emitted by ships in the port of Copenhagen contributed substantially to the overall NOx pollution in central Copenhagen. This would have an impact on human health if most of the NO were occasionally transformed into NO2, for which the European Communityʹs legal limit is defined by the 19th-highest annual hourly value being 200 μg m−3 NO2. Emissions by the ships caused a maximum 19th hourly NOx concentration of 615 μg m−3. In a small area of housing estates and office blocks near the harbour, it exceeded 200 μg m−3 NOx, and over several square kilometres of central Copenhagen, the emission by ships in harbour similarly caused values of 50–200 μg m−3 NOx. In the port of Elsinore, ferries contributed significantly to the NOx pollution in the neighbourhood around the harbour. Emissions of particulate matter (PM) by ships in Copenhagen harbour caused neighbourhood concentrations equivalent to only 0.2–0.4% of the European Communityʹs legal annual mass-based limit value for the protection of human health. However, ship emissions are dominated by ultrafine particles, as are diesel vehicle emissions, which adversely affect human health. Particulate emissions from ships contribute 8–15% of that of all urban road traffic to the background PM10 levels in the harbour neighbourhoods. In Elsinore, the PM problem was less significant than in Copenhagen. Ships in both harbours will contribute insignificantly to urban pollution with sulphur dioxide (SO2), once the anticipated regulations on sulphur content in marine fuels are implemented. In Køge, the low activity in the harbour meant that ships did not significantly affect urban air quality.