Here’s a new study on green space and health, based on the large-scale nurses’s study. One interesting finding is that mental health explains around 30% of the total benefit.

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

In models adjusted for mortality risk factors (age, race/ethnicity, smoking, and individual- and area-level socioeconomic status), women living in the highest quintile of cumulative average greenness (accounting for changes in residence during follow-up) in the 250m area around their home had a 12% lower rate of all-cause non-accidental mortality (95% CI 0.82, 0.94) compared to those in the lowest quintile. Results were consistent for the 1,250m area, although the relationship was slightly attenuated. These associations were strongest for respiratory and cancer mortality. Findings from a mediation analysis suggest that the association between greenness and mortality may be at least partly mediated by physical activity, particulate matter less than 2.5 micrometers, social engagement, and depression.