Associations between surrounding greenness, tree cover and all-cause mortality in Jordan: a 14-year nationwide panel...

The association between greenness and mortality remains largely unexamined in the Eastern Mediterranean Region (EMR). In this study, we estimated associations between long-term district-level greenness and all-cause mortality among Jordanian adults according to sex, age group, and climatic zone.

We conducted a 14-year nationwide longitudinal panel study, using district-year as the unit of analysis. Greenness was characterized using the Normalized Difference Vegetation Index (NDVI) and tree cover percentage. Associations between each greenness metric and all-cause mortality were estimated using a correlated random-effects Poisson model, with covariate adjustment sets identified through a causal inference framework. Analyses were stratified by sex, age group, and climatic zone.

No overall association was observed for either NDVI (IRR 0.959, 95% CI 0.878-1.046 per 0.1-unit increase) or tree cover (IRR 0.977, 95% CI 0.893-1.069 per 1-percentage-point increase). However, in semi-arid districts, higher NDVI was inversely associated with all-cause mortality, particularly among working-age males, with associations observed from ages 20-29 (IRR 0.744, 95% CI 0.556-0.997) through 50-59 years (IRR 0.746, 95% CI 0.613-0.906). Associations were null across all strata in arid districts. Tree cover showed a comparable but more modest pattern.

Although overall associations were null, inverse associations were observed in semi-arid districts, particularly among working-age males. Further studies using individual-level data are needed to confirm these findings and clarify potential underlying mechanisms.