Investigation on sociodemographic and health inequity of greenspace using different greenspace indicators in 3 US urban communities

Abstract

BACKGROUND AND AIM Study results are inconclusive regarding how greenspace exposure differs by sociodemographic status potentially due to lack of consideration of varying dimensions of greenspace. We investigated the inequity of greenspace and its health effects by sociodemographic status comparing various greenspace metrics. METHODS We used five metrics: vegetation levels measured by Enhanced Vegetation Index (EVI), percent greenspace, percent tree cover, percent tree cover along walkable roads, and percent people living <500m of a park entrance (park accessibility). We used data for 2008–2013 in Census block groups in 3 US regions: New Haven, Connecticut; Baltimore, Maryland; Durham, North Carolina. We examined associations between each greenspace metric and indicators of income, education, linguistic isolation, race/ethnicity, and age. Logistic regressions examined associations between these greenspace metrics and age-standardized mortality controlling for sociodemographic indicators. RESULTS The region with the highest greenspace differed across metrics. Average percent greenspace was highest in Durham and lowest in Baltimore. Average percent people living <500m of a park entrance and percent tree cover along walkable roads were highest in New Haven. An interquartile range (64.7%) increase in people of color was associated with a 6.2% (95%CI: 3.1–9.3) increase in park accessibility, whereas it was associated with 0.03–7.3% decreases in other greenspace metrics. A 15.5% increase in the lower-education population was associated with a 2.1% increase (95%CI: -0.3%–4.6%) in park accessibility but decreases with other greenspace metrics (0.02–5.0%). The odds ratios of having an all-cause standardized mortality rate ≥75th percentile were inversely associated with all greenspace metrics except for park accessibility (OR=1.40, 95% CI: 0.52–3.75). CONCLUSIONS Environmental justice concerns and health benefits of greenspace can differ by form of greenspace and socioeconomic status within communities. Comparisons of greenspace between different greenspace metrics should be incorporated in decision-making. KEYWORDS Environmental justice, greenspace, health inequity.