Integrating health impact assessment and causal layered analysis to examine transport-related health impacts: a case study of a rapidly transforming port city southeastern Iran

Health Impact Assessment (HIA) identifies health impacts but may not fully explain the structural and socio-cultural processes that sustain them. This study integrated HIA with Causal Layered Analysis (CLA) to examine transport-related health impacts and their underlying drivers in Chabahar, a rapidly transforming port city in southeastern Iran. A qualitative design combined 60 semi-structured interviews with urban managers, community activists, and residents, field observations, and a thematic analysis of policy documents. HIA guided the appraisal of perceived health impacts, while CLA examined observable problems, systemic causes, dominant worldviews, and underlying cultural narratives. Motorcycle-related injuries, reduced physical activity, stress, sleep disturbances, and declining social and spritual well-being. These concerns were linked to fragmented governance, limited inter-agency coordination, the concentration of urban services, car-oriented planning, and inadequate pedestrian and public transport infrastructure. The analysis also highlighted tensions between formal planning priorities and persistent transport problems. Integrating HIA and CLA extends impact assessment beyond identifying health impacts to examining the institutional, structural, and cultural processes that generate and sustain them. This approach can support more health-sensitive planning, strengthen attention to implementation conditions, and inform impact assessment in rapidly transforming urban contexts.