Rising global temperatures and extreme heat events have made occupational heat stress a major public health challenge, particularly among outdoor local workers and migrant workers who face prolonged exposure and inadequate protection. Despite their shared risks, the differential vulnerability patterns between these groups remain poorly characterized. The objective was to compare Heat Vulnerability Indexes (HVIs) between outdoor local workers and migrant workers to identify distinct susceptibility patterns and inform targeted interventions. A cross-sectional study was conducted in Tamil Nadu using an in-house, multidimensional Heat Vulnerability Index (HVI). The HVI incorporated socio-demographic, occupational, physiological, and environmental factors measured through field assessments, physiological monitoring, and structured questionnaires. HVI scores were derived using Factor Analysis of Mixed Data and categorized into four levels: low ( 1 °C: 21.6% vs. 9.8%) and dehydration (56.7% vs. 73.1%), with a 3.2 fold higher risk of dehydration, driven by intense workloads, inadequate hydration, and poor living conditions. Migrant workers faced higher risk, whereas local workers experienced persistent, chronic exposure risks. The worker specific HVI enables differentiation of vulnerability patterns and provides an evidence base for designing targeted heat mitigation and occupational health policies. Occupational heat stress is a major public health issue, disproportionately affecting outdoor and migrant workers. Previous studies have highlighted heat-related health risks in these groups, but differential vulnerability patterns and risk profiles remain poorly characterized. This study developed and applied a novel Heat Vulnerability Index (HVI) to compare outdoor local workers and migrant workers. Findings show that migrant workers face critically high acute vulnerability due to heavy workloads, poor hydration, and inadequate living conditions, while outdoor local workers experience moderate but chronic risks. The identification of distinct vulnerability patterns enables targeted interventions, with urgent prioritization of migrant workers for protective measures and tailored health strategies. These results provide evidence for policymakers and occupational health practitioners to design context-specific interventions and optimize resource allocation for heat risk management.
Sankar et al. (Tue,) studied this question.