that remain or that are emerging, particularly in the near term. Particularly if government capacity or regulatory structures are lacking, responses that engage a broad mix of stakeholders to integrate air-related concerns into broader policy and investment decisions (e.g. transportation planning, land-use planning, economic development investments, behavioural change) may be more capable of addressing diffuse sources of emissions and promoting innovation.
Cities have been important centres of policy innovation and policy integration and continue to provide important opportunities for progress. The non-governmental organization Clean Air Asia is a leading example of efforts in this arena, bringing together city governments, national ministries, industry and other stakeholder groups from more than 1,000
cities across Asia to share lessons in developing air pollution, climate change, transportation, land-use and energy policies (Clean Air Asia 2017). The C40 Cities Climate Leadership Group is another example, which connects officials in cities to their peers in cities around the world to exchange information as they face common challenges associated with climate change mitigation and adaptation (Day et al. 2018).
At both international and local levels, coalitions and initiatives have formed between governments, industry and other groups to facilitate specific actions. The Climate and Clean Air Coalition for Reduction of Short-Lived Climate Pollutants (CCAC) is an example of a coordinated effort to make near- term progress focused on specific pollutants and sectors (CCAC 2015).