On the first day, several important aspects of urban air quality crystallized out. These include the impact of different pre-cursors which eventually lead to the formation of ozone and particles. As shown by Volker Matthias (HZG Geesthacht), a large amount of the particle load in the Netherlands results from emissions of passing ocean ships. Thus, in order to reduce urban pollution ship emissions also need to be reduced.
Luisa Molina (MIT, USA) showed for Mexico City that emissions from large fires are pre-cursors for several pollutants and considerably increase particle loads, but have almost no impact on ozone. For the future climate, it was determined by Magnus Engardt (SMHI, Norköping) for Stockholm that ozone concentrations will increase further, if no emission reduction measures are put in place. These need not to be directly at the place where the concentrations are high. Such a far-ranging effect might, however, be limited by orography, as Alessio D Allura (Arianet, Milano) has shown for the Po valley which is one of the most polluted area in EU, but impacts the air quality outside this confined North Italian region only under certain meteorological conditions.
The conference will continue for another two days. Interactions of urban air quality and climate change will be discussed further – and the necessary model quality as well as model complexity shall be defined.