Lethal Heat and Humidity Events

Climate change increasingly threatens global health as more frequent extreme heat events, combined with varying humidity levels, exacerbate both direct and indirect health risks, strain energy resources, and lead to economic loss. Vulnerable populations, including the elderly, young children, and those with preexisting health conditions, face greater risks due to lower physiological adaptive capacity. Those from socioeconomically disadvantaged communities are also vulnerable because of increased exposure and reduced capacity. While research has expanded our understanding of the physiological effects of extreme heat and humidity, challenges persist, including inconsistent data, lack of unified heat wave definitions, and limited knowledge of their impact on mortality and morbidity especially in specific populations. Addressing these challenges requires enhanced data and a comprehensive evaluation of humidity's modifying effects. Global collaboration to strengthen heat health action plans is essential, with future efforts focusing on enhancing the accessibility and effectiveness of interventions, especially in underresourced regions.