Associations between exposure to blue spaces and natural and cause-specific mortality in Greece: An ecological study.

BACKGROUND

A growing body of evidence suggests that exposure to natural environments, such as green space, may have a beneficial role in health. However, there is limited evidence regarding the effects of exposure to blue spaces and mortality. We investigated the association of exposure to blue spaces with natural and cause-specific mortality in Greece using an ecological study design METHODS: Mortality and socioeconomic data were obtained from 1,035 municipal units (MUs) from the 2011 census data. To define exposure to "blue" we used a rate of the land cover categories related to blue space from the COoRdination and INformation on the Environmental (CORINE) 2012 map per 10,000 persons in the municipal unit. We further assessed the exposure to blue space in the MUs that are located in the coastline of Greece using the distance to the coast as a proxy for proximity to blue space. the Annual PM, NO, BC and O concentrations for 2010 were predicted by land use regression models while the normalized difference vegetation index was used to assess greenness. We applied single and two exposure Poisson regression models accounting for spatial autocorrelation and adjusting for unemployment and lung cancer mortality rates, percentages of the population aged 25-64 with upper secondary or tertiary education attainment and of those born in Greece, and urbanicity. The analysis was conducted for the whole country and separately by varying geographical definitions.

RESULTS

An interquartile range (IQR) increase of blue space per 10,000 persons was associated with decreased risk in natural mortality (Relative Risk (RR): 0.98 (95% confidence interval (CI): 0.98, 0.99), as well as in mortality due to cardiovascular causes, respiratory causes and diseases of the nervous system 0.98 (95% CI: 0.97, 0.99); 0.97 (95% CI: 0.95, 0.99); 0.94 (95% CI: 0.88, 1.00) respectively). We estimated protective associations for ischemic heart disease (IHD) mortality (RR = 0.98, 95% CI: 0.97, 1.00 per IQR); COPD mortality (RR = 0.97, 95% CI: 0.93, 1.00 per IQR) and mortality from cerebrovascular disease (RR = 0.97 (95% CI: 0.96, 0.99 per IQR). We estimated protective associations for the distance from the coast and mortality from the diseases of the nervous system (RR = 0.75, 95% CI: 0.61, 0.92, ≤1 km from the coast versus >1 km). Our results were stronger for inhabitants of the islands, the coastline and in the rural areas of Greece while the estimates were robust to co-exposure adjustment.

CONCLUSIONS

We estimated statistically significant protective effects of exposure to blue space on mortality from natural, cardiovascular and respiratory causes, diseases of the nervous system, cerebrovascular and ischemic heart disease for in Greece with higher estimates in the coastline and the islands. Further research is needed to elaborate our findings.