Associations between residential greenspace exposure and mortality in 4 645 581 adults living in London, UK: a longitudinal study

Abstract

Background: Urban greenspaces could reduce non-communicable disease (NCD) risk. The links between greenspaces and NCD-related mortality remain unclear. We aimed to estimate associations between residential greenspace quantity and access and all-cause mortality, cardiovascular disease mortality, cancer mortality, respiratory mortality, and type 2 diabetes mortality.

Methods: We linked 2011 UK Census data of London-dwelling adults (aged ≥18 years) to data from the UK death registry and the Greenspace Information for Greater London resource. We calculated percentage greenspace area, access point density (access points per km²), and distance in metres to the nearest access point for each respondent's residential neighbourhood (defined as 1000 m street network buffers) for greenspaces overall and by park type using a geographic information system. We estimated associations using Cox proportional hazards models, adjusted for a range of confounders.

Findings: Data were available for 4 645 581 individuals between March 27, 2011, and Dec 31, 2019. Respondents were followed up for a mean of 8·4 years (SD 1·4). All-cause mortality did not differ with overall greenspace coverage (hazard ratio [HR] 1·0004, 95% CI 0·9996-1·0012), increased with increasing access point density (1·0076, 1·0031-1·0120), and decreased slightly with increasing distance to the nearest access point (HR 0·9993, 0·9987-0·9998). A 1 percentage point (pp) increase in pocket park (areas for rest and recreation under 0·4 hectares) coverage was associated with a decrease in all-cause mortality risk (0·9441, 0·9213-0·9675), and an increase of ten pocket park access points per km² was associated with a decreased respiratory mortality risk (0·9164, 0·8457-0·9931). Other associations were observed, but the estimated effects were small (eg, all-cause mortality risk for increases of 1 pp in regional park area were 0·9913, 0·9861-0·9966 and increases of ten small open space access points per km² were 1·0247, 1·0151-1·0344).

Interpretation: Increasing the quantity of, and access to, pocket parks might help mitigate mortality risk. More research is needed to elucidate the mechanisms that could explain these associations.

Funding: Health Data Research UK (HDRUK).