We review recent empirical economic studies on urban ambient air pollution from a mayor's perspective. We discuss the sources of urban air pollution, the economic costs that it imposes, and the policy tools available to a mayor to alleviate it. For economic costs, we briefly summarize traditional estimates of health and mortality costs and focus on more recent evidence on mental and psychological health, labor productivity and supply, avoidance behavior, willingness to pay for clean air and long-term (multi-decade) impacts. The policy tools we evaluate include pollution information disclosure, auto license and driving restrictions, congestion tolls, public transit investments, emission standards and controls, and gasoline taxes. We also discuss challenges posed by transboundary pollution across cities and the extent to which mayors' incentives encourage tackling air pollution under different political systems. We briefly discuss possible future research agendas. JEL Codes: H23, H75, O18, Q51, Q52 Keywords: urban air pollution; environmental costs and benefits; urban public policy, environmental policies; incentives 1 This chapter was prepared for Handbook of Real Estate and Macroeconomics to be published by Edward Elgar Publishing Ltd. We thank the Editor Charles Leung for inviting us to write this chapter. We thank Jessie Qin, Tie Shi, and Yinlong Wang for providing excellent research support.