The impact of ship emissions on air quality and human health in the Gothenburg area – Part 1: 2012 emissions

Abstract

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 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 were calculated with the Ship Traffic Emission Assessment Model (STEAM), 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 to be substantial, especially in areas around the city ports. The relative contribution from local shipping to annual mean NO2 concentrations was 14 % as the model domain average, while the relative contribution from regional shipping in the North Sea and the Baltic Sea was 26 %. In an area close to the city terminals, the contribution of NO2 from local shipping (33 %) was higher than that of road traffic (28 %), which indicates the importance of controlling local shipping emissions. Local shipping emissions of NOx led to a decrease in the summer mean O3 levels in the city by 0.5 ppb (∼2 %) on average. Regional shipping led to a slight increase in O3 concentrations; however, the overall effect of regional and the local shipping together was a small decrease in the summer mean O3 concentrations in the city. In addition, volatile organic compound (VOC) emissions from local shipping compensate up to 4 ppb of the decrease in summer O3 concentrations due to the NO titration effect. For particulate matter with a median aerodynamic diameter less than or equal to 2.5 µm (PM2.5), local ship emissions contributed only 3 % to the annual mean in the model domain, while regional shipping under 2012 conditions was a larger contributor, with an annual mean contribution of 11 % of 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 decrease in the life expectancy by 0.015 years per person. The relative contribution of local shipping to the impact of total PM2.5 was 2.2 %, which can be compared to the 5.3 % contribution from local road traffic. The relative contribution of the regional shipping was 10.3 %. The mortalities due to the exposure to NO2 associated with shipping were calculated to be 2.6 premature deaths yr−1. The relative contribution of local and regional shipping to the total exposure to NO2 in the reference simulation was 14 % and 21 %, respectively. The shipping-related ozone exposures were due to the NO titration effect leading to a negative number of premature deaths. Our study shows that overall health impacts of regional shipping can be more significant than those of local shipping, emphasizing 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 (SECAs) fuel sulphur limit from 1 % to 0.1 % in 2015, leading to a strong decrease in the formation of secondary particulate matter on a regional scale was an important step in improving the air quality in the city.

The impact of ship emissions on air quality and human health in the Gothenburg area – Part II: Scenarios for 2040

“…Also, different methods of health impact assessment used in these studies are briefly reviewed. In Tang et al (2020) we discuss that shipping in Gothenburg in 2012 was a significant source of air pollution, contributing with 35 % and 12.5 % to the annual exposure to NO2 and PM2.5, respectively, and that the regional shipping outside the city was responsible for 20 % and 10 % of the NO2 and PM2.5 exposure, contributing more than the local shipping in and around the harbours. According to the study of Karl et al (2019a), the introduction of the SECA with a fuel Sulphur limit of 0.1 % decreased the exposure to PM2.5 at the Swedish West coast by approximately 35 %.…”

“…However, the abatement measures considered as well as the methods used differ from our approach. The first part of our study (Tang et al, 2020) gives a brief overview of previous studies about impacts of shipping emissions on air quality and health at the Swedish west coast. It provides discussion on how the legislation changed between the base year used in our study (2012) and the situation today.…”

“…This paper is the second part of a study about the current and future air quality situation in the Gothenburg urban area. Part 1 by Tang et al (2020) is published in the same spacial issue.…”

Urban population exposure to NO<sub>x</sub> emissions from local shipping in three Baltic Sea harbour cities – a generic approach

“…In combination with no exceedances of measured PM2.5 limit values in 2012 in any of the domains and large negative BIAS for PM2.5 due to underestimated regional background concentrations, we decided not to show the total air quality and contribution of shipping to PM2.5 here and in the exposure evaluation. Besides this, a study in preparation (Tang et al 2019) for the city of Gothenburg, showed a small impact of local shipping to PM2.5 contribution (0.07 µg m -³) but higher PM2.5 contribution from regional shipping (0.49 µg m -³).…”

“…The same regional CTM system was used in a study in preparation (Tang et al, 2019) to perform local CTM simulations in the Gothenburg area with the chemistry transport module of TAPM but with a different preparation of boundary concentrations from CMAQ: TAPM allows just 1-d boundary concentration fields with time being the only variable, and therefore the TAPM boundary concentrations were calculated using horizontal wind components on each of the four lateral boundaries for weighting the boundary concentrations. Matthias et al (2018) have discussed the necessity to utilize emission data in high spatial and temporal resolution on a coordinate grid that is in agreement with the CTM grid, due to emission data being probably the most important input for chemistry transport model (CTM) systems.…”