Evaluating Heat Stress Vulnerability and Adaptation in Malaysia: Integrating System Thinking as a Public Health Intervention

Abstract

Climate-induced heat stress poses escalating threats to public health, particularly among vulnerable populations in tropical countries. This study applies a systems thinking approach to evaluate heat stress vulnerability and adaptation capacity in Malaysia, focusing on high-risk urban and rural communities. A mixed-methods design was used, integrating physiological biomarkers (e.g., HSP70 expression, core body temperature), principal component analysis (PCA), and participatory stakeholder input into causal loop diagrams (CLDs) to model system dynamics. Distinct urban and rural CLDs were developed to map feedback loops and identify leverage points across five dimensions: environmental exposure, physiological response, housing quality, behavioral adaptation, and policy intervention. Findings revealed contrasting pathways of vulnerability. In urban settings, poor housing infrastructure and weak policy enforcement exacerbated chronic indoor heat exposure. In rural areas, prolonged outdoor work and infrastructural deficits were key contributors. Despite stronger adaptive behaviors in rural populations, systemic limitations impeded resilience. This study highlights the importance of targeting interventions to context-specific system structures. The integrated framework offers a transferable model for diagnosing heat-health risks and guiding equitable public health adaptation strategies in other tropical regions experiencing similar vulnerabilities.