Helbich, MarcoBrowning, Matthew H. E. M.Voets, DirkDadvand, Payam2025-09-172025-09-172025Helbich M, Browning MHEM, Voets D, Dadvand P. Adherence to the 3+30+300 urban green space rule and mental health, physical activity, and overweight: A population-based study in the Netherlands. Environ Int. 2025 Aug;202:109643. DOI: 10.1016/j.envint.2025.1096430160-4120http://hdl.handle.net/10230/71207Background: 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.application/pdfeng© 2025 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).info:eu-repo/semantics/articlehttp://dx.doi.org/10.1016/j.envint.2025.1096433-30-300Healthy citiesLaser scanningNature-based solutionsParksTreesUrban forestsinfo:eu-repo/semantics/openAccess