Exposure to Greenness and Mortality in a Nationwide Prospective Cohort Study of Women

http://dx.doi.org/10.1289/ehp.1510363



Table 4. Estimated proportion of association between greenness and mortality in the Nurses’ Health Study explained by physical activity, air pollution exposure, social engagement, and mental healtha,b.
Mediator Proportion of association of cumulative average greenness in 250-m buffer
explained by mediator (95% CI)
Proportion of association of cumulative average greenness in 1,250-m buffer explained by mediator (95% CI)
Abbreviations: CI, confidence interval; MET, metabolic equivalent of task; PM2.5, particulate matter < 2.5 μm in aerodynamic diameter.
aAnalyses adjusted for age and calendar year, race/ethnicity, smoking status, pack-years smoked, parental occupation, registered nurse (RN) degree, marital status, husband’s highest education, census-tract median home value, and census-tract median income. bMediation analyses assume that there is no unmeasured exposure–outcome confounding, no unmeasured mediator–outcome confounding, no unmeasured exposure–mediator confounding, and no mediator–outcome confounder affected by exposure.
Total physical activity (< 3 MET hr/week vs. ≥ 3 MET hr/week) 2.1% (0.2%, 19.3%) 1.1% (0.1%, 15.8%)
Air pollution [modeled PM2.5 < 9.7 μg/m3 (quintile 1) vs. ≥ 9.7 μg/m3 (quintiles 2–5)] 4.4% (2.4%, 7.7%) 5.1% (2.4%, 10.5%)
Social engagement (participate in groups > 1 per week vs. ≤ 1 per week) 19.1% (10.0%, 33.3%) 12.8% (6.4%, 24.0%)
Mental health (physician-diagnosed or antidepressant use vs. none) 30.6% (15.5%, 51.4%) 25.5% (12.8%, 44.4%)
All mediators combined 27.1% (14.7%, 44.6%) 19.8% (10.2%, 35.0%)