AkolaIndia’s clinicians still debate whether heat can kill.
Indian death certificates name comorbidities, not heat, as cause; researchers say India has the world’s highest heat-mortality burden but no surveillance baseline.
HeatWatch tracks cases from informal workers; no national framework mandates heat as a reportable cause of death.
Sources: Dialogue Earth
THE WET-BULB LIMIT
Wet-bulb temperature combines heat and humidity into a single number: the lowest temperature a wet surface can reach through evaporation. At 35°C wet-bulb, a healthy young adult in shade dies within roughly six hours because sweat can no longer cool the body. South Asian cities already approach 33-34°C wet-bulb during peak summer.
WHY DEATH CERTIFICATES MISS HEAT
Heat rarely kills directly. It triggers cardiac arrest, kidney failure, or stroke in someone already vulnerable. The certificate names the proximate cause — myocardial infarction, acute renal failure — and heat disappears from the record. Without an explicit reporting requirement, the signal is invisible by construction.
THE EXCESS-DEATHS METHOD
Epidemiologists work around the certificate problem by counting deaths above a seasonal baseline during heat events. France's 2003 heatwave was estimated this way at roughly 15,000 excess deaths — a figure no death certificate database produced. The method requires reliable baseline mortality data, which India's civil registration system does not consistently provide.
WHO IS EXPOSED
Heat mortality clusters among outdoor laborers, the elderly, and those without air conditioning. In India, roughly half the workforce is in agriculture or construction — outdoors during peak heat, paid by the day, with no practical option to stop working when the temperature rises.
THE DATA GAP
Two-thirds of all deaths worldwide — roughly 35 million per year — are never assigned a medical cause. Most occur in sub-Saharan Africa and South Asia, where civil registration exists on paper but lacks the doctors and infrastructure to function. Heat surveillance sits on top of that broken foundation.
WHY THE NUMBER MATTERS
A reportable cause of death drives budgets: cooling shelters, work-hour restrictions, hospital protocols, insurance payouts. Until heat appears on certificates at scale, the political pressure to fund adaptation stays weak — and the deaths keep registering as something else.