Size matters – air quality in megacities
Urban centres can have a major effect on air quality and climate as a result of human activities such as energy production, industry, transport and waste disposal. Six major centres of population in Europe have been identified as megacities. The Megapoli project is helping to formulate a European methodology for assessing the air quality and climate of megacities. The data collated will help improve sustainable management of the environment and its natural resources. The project's main objectives include determining the impacts of megacities on local, regional and global air quality and climate and evaluate the effectiveness of mitigating activities. Researchers performed two measurement campaigns around Paris for primary and secondary organic aerosol (SOA) sources and found the pollution plume was still well-defined more than 100\;km downwind. A database has been developed for evaluating surface flux and urban features used in climate and air quality models. Emission data was collated for Paris, London, Rhine-Ruhr area and the Po valley and integrated with the final European emissions map. An anthropogenic heat flux model (AHF), which shows heat flux resulting from human activities was developed and used to create a record of AHF for Europe. Data from European megacities shows that urban aerosols have a significant effect on meteorological factors such as temperature, inversion layers, cloud formation and precipitation. Satellite-based methods are also being developed and used for measuring gases and aerosols, particularly nitrogen dioxide (NO2), in and around megacities. The Megapoli initiative has brought together leading European research groups, the latest scientific tools and key figures from third countries to study the effect of megacities on local, regional and global air quality and climate. Project data has contributed to the development of a European framework for combining meteorological and atmospheric chemical transport models. The results of Megapoli will be of benefit to local authorities, policy makers, researchers and all those concerned with the impact of megacities on human health and the environment.
