The aim is to systematically identify and synthesize evidence on the specific green space settings and conditions that influence heat and air quality to answer the question: What is the evidence that green space can support health in urban communities by reducing heat and air pollution? [...] PAGE 9 Figure 1. The data gap: understanding the evidence base on green space, heat, air quality and health (a) Strong evidence base on the relationship between heat and health and air pollution and health; (b) Large and growing evidence base on the relationship between green space and health in general; (c) Growing evidence base on the relationship between green space heat and air quality but gap [...] The data set also includes first-of-its-kind studies, such as the cooling effects of parks on surrounding air and surface temperatures (see Feyisa et al., 2014), the impact of greening on individual and household-level exposure to air pollution (see Dadvand et al., 2012 and Maher et al., 2013), the impact of urban green spaces on human thermal comfort in winter (see Cohen et al., 2012), differenti [...] The first-known study of green roofs on air quality in a street canyon found that the cool air produced from the roof flows into the canyon and improves air flow and air quality near the road. [...] PAGE 23 In summary, the confluence of traffic emissions, the trees’ effect on air flow, local wind conditions and the three-dimensional configuration of the street and buildings need to be considered to determine the benefits of tree-planting in certain street canyons.