Accurately quantifying heat-related health risks is essential for reducing morbidity and mortality caused by heat stress. The US developed the Heat Index in 1979 to convey human discomfort under typical temperature and humidity conditions.
But it was built on simplified assumptions that do not adequately reflect extreme temperatures and humidities of today’s intensified heatwaves when the planet is surpassing past heat records at an alarming rate, says Sanjay Srivastava, Chief, Disaster Risk Reduction at UN-ESCAP, based in Bangkok.
“In India, for instance, heatwave season has arrived unusually early, with temperatures along the West Coast soaring in February. Scientists attribute this early onset to an exceptionally dry winter, among other factors,” Srivastava told businessline.
This period of extreme heat extends beyond typical seasonal patterns and geographical expectations. Extended Heat Index (EHI) capable of capturing heat stress even under extreme conditions is needed to improve risk assessment and preparedness. Scaling EHI across diverse climate and socio-economic vulnerability contexts will provide a more accurate measure of heat exposure.
Translational science - process of applying scientific discoveries to real-world health challenges - addresses non-economic loss and damage (NELD) associated with extreme heat. “Centre for Disaster Management at Kasturba Medical College, Manipal, is working on including an easily executable Heat Stroke Score System and its application in patient population,” Srivastava said.
Scientists have found climate change added 41 extra days of “dangerous” heat in 2024. Record global temperatures led to extreme rainfall, triggering catastrophic flooding. Of 16 floods studied, 15 were directly linked to climate change-driven rainfall.
Extreme heat poses severe health risks, as highlighted in a comprehensive analysis of temperature-attributable mortality worldwide. A study analysing data from 65 million deaths across nine countries found that extreme temperatures, hot or cold, are linked to 17 causes of death, primarily cardiorespiratory and metabolic diseases. Research published in The Lancet’s Heat and Health Series (2021) underscores how heat directly impacts human body, leading to dehydration and cardiovascular strain.
Efforts to adapt to extreme heat have led to development of Heat Action Plans (HAPs) at local level. These plans incorporate early warning systems, community engagement, targeted outreach to at-risk populations and cross-sectoral collaboration.
While HAPs have shown promising results in mitigating heat-related health risks, rising temperatures demand more effective and science-driven interventions. HAPs must integrate latest scientific findings, establish localised temperature and humidity thresholds for high-risk urban areas, and utilise risk analytics to better identify and protect most vulnerable populations.
Current approaches to managing extreme heat primarily focus on emergency response, but a broader strategy need to be adopted - one that integrates non-NELD factors into heat management frameworks, Srivastava opined.
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