Integrated strategies for road transportation-related multi-pollutant control: A cross-departmental policy mix

Road transportation significantly contributes to air pollution. However, how different air pollutant concentrations are subject to transportation-related factors and what policymakers can do to address them simultaneously remains controversial. We explore the heterogeneous effects of traffic volumes, traffic flow structure, and road network patterns on air pollutants including CO, NO2, PM2.5, and PM10, and introduce policy mixes that synergize transportation management, urban planning, and environmental monitoring based on a spatial differentiation strategy. Results show that road network patterns exhibit stronger effects on NO2 and PM10 than CO and PM2.5. A context-based policy mix is proposed in areas where all pollutants exhibit high concentrations or specific pollutants are highlighted, to address potential conflicts between policy interventions targeting different air pollutants. Such a policy-oriented framework will help in highly diversified urban areas in which a wide range of emission sources, policy authorities, and transportation infrastructure are involved in the dynamics.