In the run up to the United Nations Framework Convention on Climate Change negotiations culminating in Paris in December 2015, there has been a great deal of high-level global political focus on the issue of climate change. As air quality problems in cities from Beijing to New Delhi become increasingly severe, the links between action to address climate change and to curb local air pollution have attracted increasing attention as a means to mobilize political support. This paper highlights the interconnection that exists between reducing greenhouse gas emissions and reducing emissions of other air pollutants. It presents case studies of efforts in four cities— New York, Istanbul, Toronto, and Beijing—to improve urban air quality. These cities can provide lessons for other cities seeking to reduce the potentially severe health consequences of urban air pollution