The impact of ship emissions on air quality and human health in the Gothenburg area – Part I: 2012 emissions
Authors: Tang Lin , Ramacher Martin O. P. , Moldanová Jana , Matthias Volker , Karl Matthias , Johansson Lasse , Jalkanen Jukka-Pekka , Yaramenka Katarina , Aulinger Armin , Gustafsson Malin 
Published: February 2020

Abstract. Ship emissions in and around ports are of interest for urban air quality management in many harbour cities. We investigated the impact of regional and local ship emissions on urban air quality for 2012-year conditions in the city of Gothenburg, Sweden, the largest cargo port in Scandinavia. In order to assess the effects of ship emissions, a coupled regional and local-scale model system has been set up, using ship emissions in the Baltic Sea and the North Sea, as well as in and around the port of Gothenburg. Ship emissions are calculated with the Ship Traffic Emission Assessment Model (STEAM) model taking into account individual vessel characteristics and vessel activity data. The calculated contributions from local and regional shipping to local air pollution in Gothenburg were found substantial, especially in areas around the city ports. The local shipping contribution of NO2 to annual mean concentrations was up to 3.3 ppb, together with contribution from regional shipping at the North Sea and the Baltic Sea, the contribution was up to 4.3 ppb. In an area close to the city terminals, the contribution of NO2 from local shipping was higher than that of the road traffic, which indicates importance of controlling the local shipping emissions. The local shipping emissions of NOx decreased the summer mean O3 levels in the city by 0.5 ppb on annual mean. The regional shipping lead to a slight increase in the O3 concentrations, however, the overall effect of the regional and the local shipping together was a small decrease of the summer mean O3 concentrations in the city. For PM2.5, the local ship emissions contributed with 0.1 μg m−3 to the annual mean concentrations on the city-domain average, regional shipping was under 2012 conditions a larger contributor to the local PM2.5 than the local shipping, with an annual mean contribution of 0.5 μg m−3 on the city-domain average. Based on the modelled local and regional shipping contributions, the health effects of PM2.5, NO2 and ozone were assessed using the ALPHA-RiskPoll (ARP) model. An effect of the shipping-associated PM2.5 exposure in the modelled area was a mean loss of the life expectancy by 0.015 years per person. The relative contribution of the local shipping to the impact of total PM2.5 was 2.2 % which can be compared to 5.3 % contribution from the local road traffic. The relative contribution of the regional shipping was 10.3 %. The mortalities due to the exposure to NO2 associated to shipping were calculated to be 2.6 premature deaths/year. The relative contribution of the local and the regional shipping to the total exposure to NOLsub>2 in the reference simulation was 14 % and 21 %, respectively. The shipping related ozone exposures were due to the NO titration effect, leading to negative number of premature deaths. Our study show that overall health impacts of regional shipping can be more important than those of local shipping, emphasising that abatement policy options on city-scale air pollution require close cooperation across governance levels. Our findings indicate that the strengthened Sulphur Emission Control Areas (SECA) fuel sulphur limit from 1 % to 0.1 % in 2015, leading to strong decrease in formation of secondary particulate matter on regional scale, has been an important step in improving of the air quality in the city.