Does urban greenspace reduce racial and socioeconomic disparities in mortality in Philadelphia, PA?

Abstract

BACKGROUND AND AIM: A small body of research suggests greenspace may reduce socioeconomic health inequalities. Little is known about whether this effect extends to racial health disparities. We investigated if higher amounts of tree canopy cover or perceived park access were linked to smaller disparities in all-cause and cardiovascular (CVD) mortality rates by neighborhood SES or race composition in Philadelphia, PA. METHODS: We linked census-tract level mortality count data (years 2008-2015) with % living in poverty and % non-Hispanic Black data from the American Community Survey; LiDAR derived % tree canopy measures, and survey derived estimates of % of residents reporting perceived park access. We used age-adjusted negative binomial models, including the natural logarithm of age-specific population counts as an offset, to estimate associations between % non-Hispanic Black and % poverty (categorized in quartiles) with all-cause and CVD mortality. We quantified heterogeneity of associations across quartile-based categories of % tree canopy and perceived park access, by inclusion of interaction terms. RESULTS:Rates of mortality were higher in tracts with higher % residents living in poverty, and higher % non-Hispanic Black residents (e.g., Relative Rate [RR] of CVD mortality, highest vs. lowest quartile of % non-Hispanic Black: 1.57, 95% CI: 1.44 – 1.70). Disparities in mortality rates across categories of % living in poverty were smaller in areas with more greenspace (RR for high vs. low % poverty census tracts: 1.03 [95% CI: 0.77,1.36] among tracts with high % residents reporting access to parks; 1.76, [95% CI: 1.33, 2.33] among tracts with low % residents reporting access to parks). By contrast, disparities in mortality across non-Hispanic Black composition categories persisted, regardless of tree canopy cover or park access. CONCLUSIONS:Our preliminary results suggest that greenspace may reduce socioeconomic, but not racial health disparities. Further research is needed to clarify the reasons underlying these differences. KEYWORDS: Green space, Environmental disparities, Socio-economic factors (non-chemical stressors), Mortality, Environmental justice