Ramacher, M.O.P., Matthias, V., Aulinger, A., Quante, M., Bieser, J., & Karl, M. (2020): Contributions of traffic and shipping emissions to city-scale NOx and PM2.5 exposure in Hamburg. Atmospheric Environment, Volume 237, 2020, 117674, doi:10.1016/j.atmosenv.2020.117674
We investigated the contribution of road traffic and shipping related emissions of NO2 and PM2.5 to total air quality and annual mean population exposure in Hamburg 2012. For this purpose, we compiled a detailed emission inventory following SNAP categories focusing on the detailed representations of road traffic and shipping emissions. The emission inventory was applied to a global-to-local Chemistry Transport Model (CTM) system to simulate hourly NO2 and PM2.5 concentrations with a horizontal grid resolution of 500 m. To simulate urban-scale pollutant concentrations we used the coupled prognostic meteorological and chemistry transport model TAPM.
The comparison of modelled to measured hourly values gives high correlation and small bias at urban and background stations but large underestimations of NO2 and PM2.5 at measurements stations near roads. Simulated contributions of road traffic emissions to annual mean concentrations of NO2 and PM2.5 is highest close to highways with relative contributions of 50% for NO2 and 40% for PM2.5. Nevertheless, the urban domain is widely affected by road traffic, especially in the city centre. Shipping impact focuses on the port and nearby industrial areas with contributions of up to 60% for NO2 and 40% for PM2.5. In residential areas in the north of the port, shipping contributes with up to 20–30% for NO2 and PM2.5.
Our simulation resulted in 14% of the population of Hamburg being exposed to hourly NO2 concentration above the hourly limit of 200 μg/m³, <1% to annual NO2 concentrations above the annual limit of 40 μg/m³, and 39% to PM2.5 concentrations above the annual WHO limit of 10 μg/m³. The calculation of the population-weighted mean exposure (PWE) to NO2 and PM2.5 reveals mean exposures of 20.51 μg/m³ for NO2 and 9.42 μg/m³ for PM2.5. In terms of PWE to NO2, traffic contributes 22.7% to the total and is 1.6 times higher than the contribution of shipping (13.9%). In total, traffic and shipping contribute with 36.6% to the NO2 PWE in Hamburg in 2012. When it comes to PM2.5, traffic contributes 18.1% and is 5.3 times higher than the contribution from shipping (3.4%). In total, traffic and shipping contribute 21.5% to the PM2.5 PWE in Hamburg in 2012.
Two local scenarios for emissions reductions have been applied. A scenario simulating decrease in shipping emissions by instalment of on-shore electricity for ships at berth, revealed reduction potentials of up to 40% for total NO2 exposure and 35% for PM2.5 respectively. A road traffic scenario simulating a change in the fleet composition in an inner city zone, shows lower reduction potentials of up to 18% for total exposure to NO2 and 7% for PM2.5 respectively. The discussion of uncertainties revealed high potentials for improving the emission inventories, chemical transport simulation setup and exposure estimates. Due to the use of exposure calculations for policy support and in health-effect studies, it is indispensable to reduce and quantify uncertainties in future studies.
Tang, L., Ramacher, M.O.P., Moldanová, J., Matthias, V., Karl, M., Johansson, L., Jalkanen, J.-P., Yaramenka, K., Aulinger, A., & Gustafsson, M. (2020): The impact of ship emissions on air quality and human health in the Gothenburg area – Part 1: 2012 emissions. Atmos. Chem. Phys., 20, 7509–7530, doi:10.5194/acp-20-7509-2020
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.
Ramacher, M.O.P., Tang, L., Moldanová, J., Matthias, V., Karl, M., Fridell, E., & Johansson, L. (2020): The impact of ship emissions on air quality and human health in the Gothenburg area – Part II: Scenarios for 2040. Atmos. Chem. Phys., 20, 10667–10686, doi:10.5194/acp-20-10667-2020
Shipping is an important source of air pollutants, from the global to the local scale. Ships emit substantial amounts of sulfur dioxides, nitrogen dioxides, and particulate matter in the vicinity of coasts, threatening the health of the coastal population, especially in harbour cities. Reductions in emissions due to shipping have been targeted by several regulations. Nevertheless, effects of these regulations come into force with temporal delays, global ship traffic is expected to grow in the future, and other land-based anthropogenic emissions might decrease. Thus, it is necessary to investigate combined impacts to identify the impact of shipping activities on air quality, population exposure, and health effects in the future.
We investigated the future effect of shipping emissions on air quality and related health effects considering different scenarios of the development of shipping under current regional trends of economic growth and already decided regulations in the Gothenburg urban area in 2040. Additionally, we investigated the impact of a large-scale implementation of shore electricity in the Port of Gothenburg. For this purpose, we established a one-way nested chemistry transport modelling (CTM) system from the global to the urban scale, to calculate pollutant concentrations, population-weighted concentrations, and health effects related to NO2, PM2.5, and O3.
The simulated concentrations of NO2 and PM2.5 in future scenarios for the year 2040 are in general very low with up to 4 ppb for NO2 and up to 3.5 µg m−3 PM2.5 in the urban areas which are not close to the port area. From 2012 the simulated overall exposure to PM2.5 decreased by approximately 30 % in simulated future scenarios; for NO2 the decrease was over 60 %. The simulated concentrations of O3 increased from the year 2012 to 2040 by about 20 %. In general, the contributions of local shipping emissions in 2040 focus on the harbour area but to some extent also influence the rest of the city domain. The simulated impact of onshore electricity implementation for shipping in 2040 shows reductions for NO2 in the port of up to 30 %, while increasing O3 of up to 3 %. Implementation of onshore electricity for ships at berth leads to additional local reduction potentials of up to 3 % for PM2.5 and 12 % for SO2 in the port area. All future scenarios show substantial decreases in population-weighted exposure and health-effect impacts.