Green roofs involve growing vegetation on rooftops and are one tool that can help mitigate the negative effects of pollution. This review encompasses published research to date on how green roofs can help mitigate pollution, how green roof materials influence the magnitude of these benefits, and suggests future research directions. The discussion concentrates on how green roofs influence air pollution, carbon dioxide emissions, carbon sequestration, longevity of roofing membranes that result in fewer roofing materials in landfills, water quality of stormwater runoff, and noise pollution. Suggestions for future directions for research include plant selection, development of improved growing substrates, urban rooftop agriculture, water quality of runoff, supplemental irrigation, the use of grey water, air pollution, carbon sequestration, effects on human health, combining green roofs with complementary related technologies, and economics and policy issues.Planting on roofs and walls began in Europe, but it is now becoming popular all over the world. Green roofs and walls reduce pollution and run-off, and also help insulate and reduce the maintenance needs of buildings. Planting Green Roofs and Living Walls discusses the practical techniques required to make planting on roofs and walls a reality. It describes how roofs may be modified to bear the weight of vegetation, considers the different options for drainage layers and growing media, and lists the plants suitable for different climates and environments.