Adherence to the 3+30+300 urban green space rule and mental health, physical activity, and overweight: A population-based study in the Netherlands

Background
The 3+30+300 guideline aims to establish a standard for healthier cities to enhance population health through the provision of trees and green space; however, little empirical evidence to support its effectiveness is available.
Objectives
We aimed to 1) evaluate the adherence to the 3+30+300 urban green space rule in the Netherlands; 2) examine the associations between the 3+30+300 rule (and its components) and adults’ health and behavioral outcomes; and 3) assess possible effect modifications by age, sex, income, and urbanicity.
Methods
We used population-based health survey data for 2022 from the Netherlands. Adults’ general health, psychological complaints, anxiety and depression symptoms, psychological resilience, physical activity, and overweight were assessed alongside the 3+30+300 rule at the residential addresses. Covariate-adjusted mixed effects logistic regressions estimated the associations of health and behavioral outcomes with the 3+30+300 components—individually and jointly. Subgroup analyses based on age, sex, income, and urbanicity were also conducted.
Results
Of the 180,949 respondents, 16.4 % met the 3+30+300 rule. Respondents meeting the 3+30+300 rule were significantly less likely to be overweight and were significantly more likely to be physically active than those not meeting the rule. Neither meeting the 3+30+300 rule nor its components showed any association with other health or behavioral outcomes. We found no notable effect modification by age, sex, income, and urbanicity.
Conclusions
Our findings suggest that meeting the 3+30+300 green space rule may promote certain health benefits, particularly by supporting better weight management and higher physical activity levels, though its role in mental health remains inconclusive.