Emissions of Megacities and Their Impact on Air Quality Over Europe

PMCAMx-2008, a three dimensional chemical transport model (CTM) was applied in Europe, to quantify the influence of emissions in European Megacities (Paris, London, Rhine-Ruhr, Po Valley) on the concentration of the major PM_2.5 components. Different emissions scenarios were applied (e.g. an “annihilation” scenario zeroing all anthropogenic emissions in Megacities), and the impact of Megacities emissions on air quality within Megacities and also in the surrounding regions was investigated. Two simulation periods were used, summer 2009 and winter 2010, to study the seasonal effect of Megacities emissions. The results show that the impact of the local emissions on the concentration of total PM_2.5 within Megacities is in the 10–60% range during wintertime depending on the chemical component and in the 5–40% range during summer. Local sources are especially important for black carbon (BC) contributing more than 40% of its concentration within Megacities, during both periods (up to 90% in Po Valley). Megacities emissions also influence the air quality of the surrounding regions within an average radius of 250 km from the Megacity.