Résumé : Abstract Aim This study examines how urban planning in Belgium impacts public health by influencing air pollution and green space. It analyses the link between these environmental factors and health issues such as mortality, cardiovascular disease, diabetes, asthma, and depression. Subject and methods This study quantifies the combined disease burden attributable to fine particulate natter (PM 2.5 ), NO 2 , and insufficient green space in Brussels, Liège, and Mechelen using a multiplicative population preventable fraction (PF) approach with World Health Organization (WHO) exposure target values as counterfactual scenario. Results Our findings reveal that reducing PM 2.5 and NO 2 and increasing green space to WHO-recommended levels could lower total mortality by 14.7% (95% CI 9.4–19.8) in Brussels, 11.7% (95% CI 7.5–16.3) in Liège, and 12.0% (95% CI 7.7–16.3) in Mechelen. Cardiovascular mortality could decrease by 13.4% (95% CI 5.8–21.0) in Brussels, 10.3% (95% CI 4.1–16.0) in Liège, and 11.0% (95% CI 5.1–16.6) in Mechelen. Diabetes reductions are estimated at 25.4% (95% CI 7.0–40.3) in Brussels, 21.6% (95% CI 7.2–37.0) in Liège, and 19.9 (95% CI 6.7–33.9) in Mechelen. Focusing on background concentrations for NO 2 underestimates health effects. Traffic contributes 73.2–78.6% of NO 2 , with local traffic accounting for 40.9–55.0% of concentrations. Conclusion This study identifies a statistically significant link between elevated air pollution, limited green space, and the potential to reduce chronic disease prevalence by adhering to WHO guidelines. It underscores the importance of health-centred urban planning, advocating for green space expansion, air quality improvements, and more precise NO 2 source allocation to better pinpoint and mitigate pollution sources, ultimately fostering healthier communities.