Projecting long-term population health benefits of urban greening in Barcelona: a life-table modelling approach.

BACKGROUND: Urban greening is increasingly promoted as a strategy to improve population health, yet most assessments focus on impacts within a single year under static population conditions. METHODS: We conducted a long-term Health Impact Assessment (HIA) of two urban greening scenarios in Barcelona - the Green Corridors (EV) programme and the Urban Master Plan (PDUM) - using a longitudinal life-table modelling framework. Changes in greenness were estimated at the census tract level and linked to mortality and morbidity outcomes through exposure-response functions (ERFs). Health impacts were projected from 2022 to 2100, accounting for projected changes in population size and age structure, and quantified in terms of avoided deaths, incident disease cases and disability-adjusted life years (DALYs). FINDINGS: Both scenarios resulted in substantial health gains that increased over time, with larger benefits under EV. By 2050, EV was estimated to prevent 1,537 (95% CI: 940-2,218) deaths among women and 2,753 (1,685-3,971) among men, compared with 1,239 (760-1,791) and 2,209 (1,354-3,197) under PDUM. By 2100, cumulative avoided deaths increased to 5,224 (3,195-7,542) and 9,459 (5,790-13,646), respectively. When considering overall disease burden, both scenarios resulted in large reductions in DALYs. Health gains varied across space and socioeconomic groups, with larger benefits observed in intermediate socioeconomic quintiles. INTERPRETATION: Urban greening strategies can generate substantial long-term population health benefits, particularly when evaluated using approaches that account for demographic change and cumulative impacts. Integrating health considerations into urban planning can support both population health and equity-oriented urban planning.