Are greener cities healthier? An investigation into the association between green space coverage and health at the city level, in England

摘要

Background. Green space has been identified as a modifiable feature of the urban environment that has relevance to the health and wellbeing of residents. Associations between the availability of green space and physiological and psychological health have been found at the ward and neighbourhood levels. Aim. This study aims to assess the association between health and green space at a larger scale, with English cities as the unit of analysis. Methods. An ecological, cross sectional study design was used. Land use within 50 English cities was classified using satellite-based data. This enabled quantification of the proportion of each city's total area covered by green space. Negative binomial regression models were used to assess the association between city green space coverage and the standardized risk of death from all-causes, cardiovascular disease, suicide and lung cancer, with and without adjustment for relevant confounders. Results. No independent association between green space coverage in English cities and risk of death from all-causes, CVD, lung cancer or suicide in men or women was found. Following adjustment for income deprivation, air pollution and population density, the risk of death from all-causes, CVD and lung cancer, for men and women, and suicide for men only, in the greenest cities did not significantly differ from the risk found in the least green cities; the greenest cities had a significantly excess risk of female suicide. Conclusion. These null findings, as opposed to the positive associations found between green space and health outcomes in published studies conducted at smaller area unit levels, suggest the effects of green space may be local. Further work at smaller area level should seek to account for variation in factors excluded from the present study due to the lack of appropriate data, yet likely to influence the use of available green areas, and hence the relationship between green space and health.