Exploring the role of land-sharing on urban green and cardiovascular health

Abstract

Background Several studies have investigated the association between green infrastructure and human health in cities and showed a positive relationship, as the amount or proximity to green spaces related with a reduction in the risk of cardiovascular diseases, in small geographical scales such as a few minutes walking to access those green areas. We aimed to investigate the effects of green spaces in the number of cardiovascular hospitalisations at an administrative scale (city districts), considering not only the quantity, but also the distribution of green spaces. We also aimed to predict the relative risk of cardiovascular hospitalisation related to the type and distribution of vegetation.Methods We used a land-sharing-sparing approach, accessed by vegetation indexes adapted to urban areas, to estimate the level of land sharing and sparing in each of the 96 districts of São Paulo (Brazil). We also used a vegetation cover map to access the quantity and type of green coverage in each district. We ran a binomial generalised linear model, considering the relative number of hospitalisations in each district in relation to the total population of exclusive users of the public health system. We then constructed models of those hospitalisation rates versus the type of vegetation and distribution (land-sharing-sparing metrics), controlled by social metrics.Findings We found that the best model selected by Akaike information criteria was the model considering total green coverage and land sharing (92% of total weight), with sharing having a bigger effect (β -0•82064, SD 0•05376) than coverage (β -0•15906, 0•04296) in the decrease of cardiovascular hospitalisation rates.Interpretation Our results show the importance of having neighbourhoods that share green spaces and households, potentially through street trees, green squares, parks, and small gardens, with distribution more important for cardiovascular health than simple coverage, perhaps because of a scenic view effect, encouragement of outdoor activities, and daily contact with those areas. Decision makers should consider strategies that increase the green coverage between households, promoting increased contact with green spaces as a potential incentive to experience green spaces and the prevention of cardiovascular hospitalisation.