This report is authored by the Pollution and Health Unit of the United Nations Environment Programme (UNEP). Staff members involved in its production include Soraya Smaoun, Victor Nthusi, Maria Cristina Zucca, Valentin Foltescu and Richard Miesen. The report was prepared with the assistance of Orbis Air, LLC including Gary Kleiman and Susan Anenberg. The team expresses great appreciation to a number of internal UNEP reviewers who provided comments on early drafts including Kakuko Nagatani-Yoshida, Maria Katherina Patdu, Tomas Marques, Jordi Pon, Luisa Gonzalez, Hilary French, Iyngararasan Mylvakanam, Charles Sebukeera, Sean Khan, Rob De Jong, Jane Akumu, Bert Fabian, Maria Socorro Manguiat, Pushpam Kumar, Atif Ikram Butt, Monika MacDevette and Ligia Noronha. We also wish to thank a panel of external reviewers that included Ernesto Sanchez-Triana of the World Bank, Sara Terry of the United States Environmental Protection Agency, Beatriz Cardena of the World Resources Institute, Tirusha Thambiran of the Council for Scientific and Industrial Research, South Africa, Sophie Gumy of the World Health Organization, Johan Kuylenstierna of the Stockholm Environment Institute, George Mwaniki of the Patra Foundation, Kenya, Najat Saliba of the American University of Beirut, Lebanon, Frank Murray of Murdoch University, Australia and Nguyen Thi Kim Oanh of the Asian Institute of Technology. The team also wishes to thank all representatives of Member States that responded to the survey, enabling this assessment.