Assessing life expectancy disparities in Chicago with a deep dive into green space

Abstract

BackgroundFew studies have examined the association between green space and life expectancy, and only one study has looked at that data for small areas in the United States. These studies have found a positive association between green space and life expectancy. This study investigates the association between green space and small-area life expectancy in Chicago, a city in the United States with distinct environmental and socioeconomic characteristics and the largest U.S. life expectancy gap between neighborhoods. MethodsWe conducted a spatial analysis using the green space metrics of normalized difference vegetation index (NDVI), park access, and tree canopy. Additionally, we included 18 lifestyle, environmental, and social covariates. Diagnostic analytics included multiple linear regression, Moran I test for spatial dependence, and principal component analysis with CAR Gaussian model. We performed a simulation to predict life expectancy gain if NDVI was brought to median levels. ResultsOur study revealed that after adjusting for covariates and spatial dependence (Moran I test p = 0.012) with a CAR Gaussian model, NDVI (credible interval = 0.292-0.894) demonstrated significance at a 5 % level, while tree canopy (credible interval = -0.404-0.109) and park access (credible interval = -0.258-0.161) did not. Excluding non-significant variables (tree canopy and park access) from the CAR Gaussian model, the median effect of NDVI on life expectancy was 0.491 (95 % credible interval: 0.24–0.718). Projecting this effect to tracts below the median NDVI predicted a gain of 476,000 years of life expectancy for Chicago residents. ConclusionThis study provides evidence that green space and LE are positively correlated, suggesting the potential to increase green space to address current LE gaps. Future research should investigate the mechanisms by which green space correlates to lifespan.