This project is associated with the proposal for the compute project 2024/5-296. The aim of the project is to assess the effects of the IMO's NOx regulations in the Baltic Sea and the North Sea on air quality and health in Swedish port cities, using Gothenburg as an example. It will also investigate effects of non-compliance and if regional and local measures, such as for example Clean Shipping Index and on-shore electricity in ports, can accelerate the reduction of NOx emissions from shipping in the region. The project builds on results from the Horizon2020 projects SCIPPER and EMERGE and is a research project funded by the Swedish Transport Administration. While emissions of SOx have largely decreased after the latest, most stringent, fuel sulphur content limits entered into force (0.1% in SECAs in 2015, 0.5% globally in 2020), both the absolute and especially the relative contribution of the shipping sector to the burden of emissions of NOx in Europe has been increasing, and in 2020 the share of NOx emissions from shipping on seas surrounding the continent corresponded to 50% of total emissions from all land sources in the EU. Since ships have a rather long lifetime, most of the emission scenarios forecast a very slow decrease of NOx emissions from shipping, with the full effect of the NECA implementation in Northern Europe being around year 2040. Furthermore, recent ship plume monitoring results reveal an increasing, instead of expected decreasing, trend in mean NOx emission factor for ships in the North Sea, which can be correlated to an increased share of the TIER II ships which also show a higher rate of noncompliance than Tier I ships. It has also been observed that Tier III ships will have higher emissions than expected when running at medium to low engine loads, which is often the case close to land; the reason is at least partly that the legislation allows for this, and that SCR system works poorly at low engine loads. Around 50% of Tier III ships were observed to have much higher emissions than the Tier III limit. Thus, there is a risk that the situation with high NOX emissions from shipping and high contribution to health risks, will persist for a long time. In this project we will use scenarios and dispersion modelling to analyse: -What is the effect on health risks if the emissions are higher than anticipated in the NOx-legislation, as observed for a large number of ships? -What is the effect of policy measures aimed at reducing the NOx emissions? A set of scenarios downscaled to the region around Gothenburg will be developed and used in a city-scale model to investigate impacts of the different measures on air pollution situation in the city for 2030 and 2040. Along with assessment of air pollution in the scenarios with respect to the air quality indicators, the impacts of air pollution on human health and the associated costs will be calculated.