This report was researched and drafted by Prof. Dr. Eloise Scotford, Professor of Environmental Law, Centre for Law and Environment, UCL Faculty of Laws, University College London and Prof. Dr. Delphine Misonne, Professor of Environmental Law, Fund for Scientific Research (FNRS) Research Associate and Director of Cedre, Université Saint-Louis Bruxelles. Sean Tseng and Flora McCarthy provided invaluable research assistance, and Michael Rudko managed the research data expertly. An initial draft of the report was presented to focal points of the Fifth Montevideo Programme for the Development and Periodic Review of Environmental Law and the Convention on Long-Range Transboundary Air Pollution (CLTRAP) at webinars organized from 28 September to 9 October 2020. Maria Cristina Zucca, Head of the Pollution and Health Unit; Soraya Smaoun, Air Quality Coordinator, and Victor Nthusi, Pollution and Health Unit, of the Economy Division of the United Nations Environment Programme (UNEP) provided expert input. A final critical review of the report was undertaken by Arnold Kreilhuber, Acting Director and Maria Socorro Manguiat, Head of the National Environmental Law Unit, with support from Soo Young Hwang and Allan Meso, Legal Officers and Lais Paiva Siqueira, Associate Legal Officer, with the Law Division of UNEP.