Greenspace exposure and non-injury mortality in UK Biobank

Abstract

Background: Some cohort studies have shown a protective association of greenness and non-injury mortality, after adjustment for personal contextual and area-level confounding factors, though evidence in the UK is predominantly from ecological studies. We aimed to assess the association of greenspace and non-injury mortality in the UK, using rich confounder data available in the UK Biobank cohort. Methods: We used Ordnance Survey MasterMap Greenspace data, categorized into 18 greenspace functions (e.g., private garden, public park, allotment, cemetery, playing field, etc.) to assess associations of survival and total greenspace cover (18 categories combined) in multiple buffer sizes (100 m, 500 m, 1000 m) surrounding UK Biobank residential addresses (n = 277,236). We used Cox-proportional hazards models, with age as the underlying timescale, adjusted for sex, household income, pack years smoking, alcohol consumption and neighbourhood deprivation. Results: We showed protective associations for UK Biobank participants living in the most green compared to the least green quintile of total greenspace cover in a 100 m circular distance buffer for non-injury mortality (HR = 0.91; 95% CI = 0.84, 0.99). Results were consistent with previous studies, which have shown a small protective association, after adjustment for confounders. Function-specific analyses showed that protective associations of private (residential) garden and mortality remained when other functional greenspace categories were excluded from analysis. Across all buffer sizes, over 50% of total greenspace cover was classified as private (residential) garden, which has important implications for environmental equality. Conclusion: Further analyses of greenspace categories, grouped by function (e.g., private (residential) gardens versus public parks, playing fields and sports facilities) will offer novel insight into specific mechanistic pathways connecting greenspace and health (e.g., the contribution of physical activity), which is critical for designing and/or retrofitting urban environments for health.