Urban population exposure to NOx emissions from local shipping in three Baltic Sea harbour cities – A generic approach


Ship emissions in ports can have a significant impact on local air quality (AQ), population exposure, and therefore human health in harbour cities. We determined the impact of shipping emissions on local AQ and population exposure in the Baltic Sea harbour cities Rostock (Germany), Riga (Latvia) and the urban agglomeration of Gdansk-Gdynia (Poland) for 2012. An urban AQ study was performed using a global-to-local Chemistry Transport Model chain with the EPISODE-CityChem model for the urban scale. We simulated NO2, O3 and PM concentrations in 2012 with the aim to determine the impact of local shipping activities to outdoor population exposure in Baltic Sea harbour cities. Based on simulated concentrations, dynamic population exposure on outdoor NO2 concentrations for all urban domains was calculated. We developed and used a novel generic approach to model dynamic population activity in different microenvironments based on publicly available data. The results of the new approach are hourly microenvironment-specific population grids with a spatial resolution of 100 × 100 m2. We multiplied these grids with surface pollutant concentration fields of the same resolution to calculate total population exposure. We found that the local shipping impact on NO2 concentrations is significant, contributing with 22 %, 11 %, and 16 % to the total annually averaged grid mean concentration for Rostock, Riga and Gdansk-Gdynia, respectively. For PM2.5, the contribution of shipping is substantially lower with 1–3 %. When it comes to microenvironment-specific exposure to annual NO2, the highest exposure to NO2 from all emission sources was found in the home environment (54–59 %). Emissions from shipping have a high impact on NO2 exposure in the port area (50–80 %) while the influence in home, work and other environments is lower on average (3–14 %), but still with high impacts close to the port areas and downwind of them. Besides this, the newly developed generic approach allows for dynamic population exposure calculations in European cities without the necessity of individually measured data or large-scale surveys on population data.
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