Exploring links between greenspace and sudden unexpected death: A spatial analysis.

Environ Int. 2018 Feb 5;113:114-121. doi: 10.1016/j.envint.2018.01.021. [Epub ahead of print] Wu J1, Rappazzo KM2, Simpson RJ Jr3, Joodi G3, Pursell IW4, Mounsey JP4, Cascio WE2, Jackson LE5. Author information 1 Oak Ridge Institute for Science and Education, US EPA, Office of Research and Development, Research Triangle Park, Durham 27711, NC, USA. Electronic address: w_jianyong@hotmail.com. 2 US EPA, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Research Triangle Park, Durham 27711, NC, USA. 3 Division of Cardiology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. 4 Division of Cardiology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; The Department of Cardiovascular Sciences, East Carolina University, Greenville, NC 27834, USA. 5 US EPA, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Research Triangle Park, Durham 27711, NC, USA. Electronic address: Jackson.Laura@epa.gov. Abstract Greenspace has been increasingly recognized as having numerous health benefits. However, its effects are unknown concerning sudden unexpected death (SUD), commonly referred to as sudden cardiac death, which constitutes a large proportion of mortality in the United States. Because greenspace can promote physical activity, reduce stress and buffer air pollutants, it may have beneficial effects for people at risk of SUD, such as those with heart disease, hypertension, and diabetes mellitus. Using several spatial techniques, this study explored the relationship between SUD and greenspace. We adjudicated 396 SUD cases that occurred from March 2013 to February 2015 among reports from emergency medical services (EMS) that attended out-of-hospital deaths in Wake County (central North Carolina, USA). We measured multiple greenspace metrics in each census tract, including the percentages of forest, grassland, average tree canopy, tree canopy diversity, near-road tree canopy and greenway density. The associations between SUD incidence and these greenspace metrics were examined using Poisson regression (non-spatial) and Bayesian spatial models. The results from both models indicated that SUD incidence was inversely associated with both greenway density (adjusted risk ratio [RR] = 0.82, 95% credible/ confidence interval [CI]: 0.69-0.97) and the percentage of forest (adjusted RR = 0.90, 95% CI: 0.81-0.99). These results suggest that increases in greenway density by 1 km/km2 and in forest by 10% were associated with a decrease in SUD risk of 18% and 10%, respectively. The inverse relationship was not observed between SUD incidence and other metrics, including grassland, average tree canopy, near-road tree canopy and tree canopy diversity. This study implies that greenspace, specifically greenways and forest, may have beneficial effects for people at risk of SUD. Further studies are needed to investigate potential causal relationships between greenspace and SUD, and potential mechanisms such as promoting physical activity and reducing stress. KEYWORDS: Bayesian spatial model; Eco-health; Ecosystem services; GIS; Green space PMID: 29421400 DOI: 10.1016/j.envint.2018.01.021