Exposure to air pollution, blue and green spaces and cause-specific mortality in Greece: An ecological study

Abstract

BACKGROUND AND AIM: Previous studies have documented the effects of long-term exposure to ambient particulate pollution on mortality outcomes, while recently there is growing interest in the effects of green and blue spaces and their possible synergistic effects. We investigated the association of exposure to air pollution, green and blue spaces with cause-specific mortality in Greece using an ecological study design. METHODS: We collected socioeconomic and cause-specific mortality data for 1,035 Municipal Units (MU) from the 2011 Census. Annual fine particulate matter (PM2.5), nitrogen dioxide (NO2), black carbon (BC) and ozone (O3) concentrations for 2010 were predicted at 100x100m grids by hybrid LUR models and a weighted average based on the built-up area percentage of each MU was estimated. The normalized difference vegetation index (NDVI) and the percentage of water bodies were used to assess exposure to green and blue spaces. We applied single and two-exposure Poisson regression models on standardized mortality rates accounting for spatial autocorrelation. RESULTS:PM2.5 was associated with increased mortality from cardiovascular and respiratory causes (Relative Risk (RR): 1.10 and 1.11, per 3.34 μg/m3 respectively), ischemic heart disease (RR: 1.05), cerebrovascular diseases (RR: 1.14) and also from diseases of the nervous system (RR: 1.14). Both BC and NO2 were associated with cardiovascular and cerebrovascular mortality. No associations with O3 were found. NDVI was associated with lower cause-specific mortality (RR: 0.90; 0.92; 0.91 per 0.16 for chronic obstructive pulmonary disease, respiratory mortality and mortality from diseases of the nervous system, respectively), while we did not find any association between exposure to blue spaces and mortality. Estimates were mostly robust to co-exposure adjustment. CONCLUSIONS:Our results support independent associations of air pollution and greenness with mortality. Further research is needed to investigate the role of blue spaces and the possible complex interactions between components of the physical environment. KEYWORDS: Air pollution, Blue space, Green space, Long-term exposure, Mortality