The symposium will investigate the tropospheric composition, how this is altered by human activities and the natural variability of the environment and the impact of these changes on air quality and climate. The symposium invites presentations on new findings on emissions, transport and transformation of pollutants in the troposphere that highlight the relations between induced forces and impacts to the environment. Attention will be given to the interactions between natural and anthropogenic substances, element cycles as well as gaseous and particulate phases in the troposphere. There are many major international projects related to these topics like AC&C (IGAC/SPARC), T&TP in ACCENT, the Megacities-Asia subproject of IGAC (and the two new EU FP7 projects MEGAPOLI and CITYZEN), from which we especially welcome contributions. The symposium welcomes laboratory, field, remote sensing and modelling investigations as well as integration of observations and modelling. Specific topics of interest are outlined:

• Emissions (emission inventories, emission factors, gases and aerosols, inverse modelling, constrains).
• Atmospheric transport and transformation of pollutants, including aerosols.
• Oxidizing capacity in the troposphere (daytime/nighttime chemistry, free radicals, organics, missing reactivity, halogen chemistry).
• Chemistry at the interfaces (ice/ snow/ aerosols/precipitation)
• Role of Megacities and other 'hot spot' areas on regional air quality and climate.
• Observing atmospheric composition change, including remote sensing and state of the art observations

• Yugo Kanaya, Frontier Research Center for Global Change,
  Yokohama, Japan