The impact of shipping emissions to urban air quality in Europe – Detailed port-city analysis
Air pollutants concentrations have shown a declining trend over the last decades in Europe as a result of decreasing emissions in many sectors. However, the strong emission reductions in some sectors, such as traffic, have shifted the focus to other less strongly contributing sources, such as shipping whose emissions relative contributions increase, in order to further reduce air pollutant concentrations.
In this report the influence of shipping emissions on the air quality in European port cities is investigated with the chemical transport model LOTOS-EUROS. Using the model’s source apportionment capabilities, the contribution of international and inland shipping emissions to atmospheric air pollutant concentrations in 19 European port cities is computed.
In the emission set used in this study, the shipping emission on seas are derived from Automatic Identification System (AIS) data of all ships sailing in the total geographic domain of the calculations. These emissions are higher than the emissions reported to the European Environment Agency (EEA) as a result of the restrictive definition of maritime emissions in the national inventories of the EU Member States which do not include any shipping emission outside the territorial waters of the Member States. The total European NOx emissions used in this simulation are ~9.3 Mton for the simulation domain of which 64 kton (0.7%) originates from inland shipping and 2.2 Mton (23%) originates from international shipping emissions.
For the entire European domain, international shipping is predicted to contribute about 18% to the atmospheric surface concentration of NO2 in 2018. This is the average contribution to the surface concentration in the entire simulation domain that includes sea covered areas. For SO2, PM2.5 and PM10 the contributions are at respectively about 11%, 5% and 3%. Inland shipping has only a minor contribution (<1%) for the average annual pollutant concertation for all investigated components.
Locally, shipping emissions contribute significantly to atmospheric pollutant concentrations in areas around big ports and port cities. For example, in the Rijnmond region around Rotterdam almost 30% of the NO2 annual mean concentration in 2018 originates from a combination of international and inland shipping emissions. Similar relative contributions are found for other cities with large ports, while in some cases (e.g. Piraeus) the contribution of shipping emissions is predicted to be dominant compared to other sectors. For all the port cities examined, the relative contribution from international shipping was 22% on average, while the contribution is 28% on average when only sea ports are taken into account. This shows the significance of emissions from shipping on the local air quality in cities around big ports in Europe and indicates that mitigation policies aimed at reducing emissions from shipping can be effective for improving the air quality in port-cities.
Meteorological conditions play an important role in physical and chemical processes in the atmosphere and hence may influence pollutant concentrations. For port-cities a particular windspeed and -direction ‘optimally’ transport a pollutant with a given lifetime from the port into the city center and thereby cause most severe air quality deterioration attributable to the port activities.