This report specifically deals with airpollution, which was reported, by the World HealthOrganization (WHO), as the single largest environmentalhealth risk globally in 2012 (WHO, 2014a). Air pollutionfrom outdoor and household sources jointly account for morethan 7 million deaths (3.7 million from ambient airpollution and 4.3 million from household air pollution). Thefollowing sections of this chapter present the objectivesof, and key aspects of the institutional context for, thisreport followed by an examination of some of the majordrivers of deteriorating ambient air quality in developingcountries; air pollution sources and impacts; and the statusof air quality management in developing countries. Chaptertwo presents the results of a desk-based portfolio review ofWorld Bank projects that are relevant to reduction of airpollution. This is followed, in chapter three, by anexamination of case studies of World Bank projects whoseobjectives include addressing ambient air pollution,highlighting good practices and lessons for future work ofthe Bank in supporting clients. Chapter four presentspossible approaches for enhancing future Bank support inhelping clients to improve air quality and reduce theassociated adverse health outcomes. Chapter five presentsoverall conclusions and recommendations.