CityZen Objectives

The objectives of CityZen are:

• Quantify and understand current air pollution distribution and development in and around selected megacities/hot spot regions, including the interaction across the different spatial scales
• Estimate the future impact from emission changes with a focus on the effect of rapid growth in the population of megacities/hot spots and the increasing background of pollutants (concentrate on ozone O3, particulate matter PM, and their precursors)
• Estimate how megacities/hot spots influence climate change
• Estimate how megacities are responding to climate forcing which can influence transport patterns, chemical oxidation and biogenic emissions (especially biogenic volatile organic compounds BVOC)
• Study mitigation options, e.g. by introducing biofuel, to keep the air pollution load in and around megacities/hot spots within sustainable limits in terms of human health effects and climate impact.
• Develop tools to estimate interactions between different spatial scales (megacities to global)
• Bring the scientific results and methods developed and applied during the course of the project to semi-operational use with those consortium partners that on a more permanent basis provide technical underpinning of policy work, that is, ensure an excellent return on the investment in the project both during and after the project has ended.

Examples of hypotheses to be tested:

• Megacities and hot spots have changed the regional and global distribution of ozone, particulate matter, and their precursors including carbon monoxide CO and other pollutants significantly compared to what would be the case with more evenly distributed emissions.
• Megacities affect the radiative budget and aerosol microphysics such that precipitation and the number of sunlit hours and thus temperature and photochemistry change significantly both locally and over larger regions. This may become more significant in the future as megacities and their emissions grow.
• Climate change will change weather patterns (winds, temperature, stability, precipitation) and surface properties, which affect air quality in megacities and regional hot spots. If more frequent high pressure situations occur, episodes with reduced air quality will become more frequent.
• Climate change will induce episodic and permanent changes in the natural and anthropogenic cycles of atmospheric trace chemicals.
• Changes in frequency and intensity of forest fires and other biomass burning will at times contribute significantly to air pollution in megacities and hot spots.
• Measures can be defined that reduce the adverse effects of megacity/hot spot emissions. The adverse effects relate both to air quality (human health) and climate change/weather modification.
• The effect on air quality in some megacities following the replacement of gasoline in parts by biofuel is to reduce the formation of secondary pollutants: aerosols and ozone.