Green space and mortality in European cities: a health impact assessment study

Background: Natural outdoor environments including green spaces play an important role in preserving population health and wellbeing in cities, but the number of deaths that could be prevented by increasing green space in European cities is not known. We aimed to estimate the number of natural-cause deaths among adult residents that could be prevented in cities in 31 European countries, if the WHO recommendation for universal access to green space was achieved. Methods: In this health impact assessment study we focused on adult residents (aged ≥20 years; n=169 134 322) in 978 cities and 49 greater cities, in 31 European countries. We used two green space proxies: normalised difference vegetation index (NDVI), and percentage of green area (%GA). The exposure was estimated at a fine grid-cell level (250 m × 250 m) and the preventable mortality burden for 2015 was estimated at the local city-level. Findings: For 2015 we found that meeting the WHO recommendation of access to green space could prevent 42 968 (95% CI 32 296–64 177) deaths annually using the NDVI proxy (ie, 20% [95% CI 15–30] of deaths per 100 000 inhabitants-year), which represents 2·3% (95% CI 1·7–3·4) of the total natural-cause mortality and 245 (95% CI 184–366) years of life lost per 100 000 inhabitants-year. For the %GA proxy 17 947 (95%CI 0–35 747) deaths could be prevented annually. For %GA the number of attributable deaths were half of that of the NDVI and results were non-significant due to the exposure response function considered. The distribution of NDVI and %GA varied between cities and was not equally distributed within cities. Among European capitals, Athens, Brussels, Budapest, Copenhagen, and Riga showed some of the highest mortality burdens due to the lack of green space. The main source of uncertainty for our results was the choice of the age-structures of the population for the NDVI analysis, and exposure-response function for the %GA analysis. Interpretation: A large number of premature deaths in European cities could be prevented by increasing exposure to green space, while contributing to sustainable, liveable and healthy cities. Funding: GoGreenRoutes, Internal ISGlobal fund, and the United States Department of Agriculture Forest Service.