There is mounting concern for the health of urban populations as cities expand at an unprecedented rate. Urban green spaces provide settings for a remarkable range of physical and mental health benefits, and pioneering health policy is recognizing nature as a costeffective tool for planning healthy cities.
Despite this, limited information on how specific elements of nature deliver health outcomes restricts its use for enhancing population health. We articulate a framework for identifying direct and indirect causal pathways through which nature delivers health benefits, and highlight current evidence.
We see a need for a bold newresearchagenda founded on testing causality that transcends disciplinary boundaries between ecologyandhealth. Thiswill lead to cost-effective and tailored solutions thatcouldenhance population health and reduce health inequalities.