Associations of greenspace and cardiorespiratory mortality are driven by private residential gardens: observational evidence from UK Biobank

Abstract

BACKGROUND AND AIM: Longitudinal evidence linking urban greenspace to reduced rates of all-cause and cause-specific mortality has mostly been established using greenness measures of limited specificity such as indices of vegetation (e.g. the Normalized Difference Vegetation Index). Here, we explored the effect of greenspace function on premature cardiorespiratory mortality in a national cohort, by analyzing types of greenspace in proximity to place of residence. METHODS: We assessed associations of greenspace type (including private residential garden, public park, etc.) with all-cause, non-injury, cardiovascular disease (CVD) and respiratory disease deaths using UK Biobank in England – a large, national prospective cohort of adults. We adjusted for individual and area-level confounders, and stratified analyses by sex, household income, and area-level deprivation. In sensitivity analyses, we further adjusted for air pollution, road-traffic noise, indirect household/workplace smoke exposure, physical activity, and length of time residing at address. RESULTS:In 232,926 participants we observed 13,586 all-cause, 13,645 non-injury, 2881 CVD, and 1015 respiratory disease deaths during 2,577,044 person-years of follow-up. The amount of private residential garden cover was inversely associated with all-cause, non-injury, CVD, and respiratory disease mortality, after adjustment for confounders. Effect estimates were also protective, though attenuated, for total greenspace cover and premature mortality. Findings were robust to sensitivity analyses. Stratified analyses indicated that sex, household income, and area level deprivation modified associations. CONCLUSIONS:Our finding that private residential gardens substantially contributed to protective associations of total greenspace and premature mortality has implications for greening policies. Inequities in access, ownership, and use of private residential gardens, and potential health inequities, should be addressed. KEYWORDS: Green space, Built environment, Cardiovascular diseases, Respiratory diseases, Mortality, Environmental disparities