[Relevance of green, shaded environments in the prevention of adverse effects on health from heat and air pollution in urban areas].

Adaptation to a warmer world is a priority, especially in large urban centers where the concentration of the population and the urban heat island increase heat-related risks. Cities are also willing to improve their air quality. This paper summarizes and discusses the current knowledge on how green spaces may be used to reduce heat-related health impacts, and on the potential co-benefits, especially through air quality. The literature shows that vegetation contributes to the creation of cool islands in cities, and to locally decrease temperature and air pollutant concentrations. Few epidemiological studies have investigated the associated health impacts, but they indicate that vegetation is probably a protective factor that reduces mortality and morbidity during heat waves. Green spaces can also contribute to the restoration and the building of resilience capacities, thus reducing the health impacts of heat and pollution. Current knowledge allows to develop green space strategies adapted to optimize the benefits in terms of urban heat island, thermal comfort and air quality, with potentially large health benefits. Only a part of those benefits can be quantified with the current health impact assessment tools.