Heat and Healthcare Utilization in the Tropics: Evidence from India

We estimate the effect of physiological heat stress on tertiary healthcare utilization and its fiscal cost using the universe of claims from a statewide social health insurance program in Andhra Pradesh, a large tropical Indian state (2007-2015). Exploiting plausibly exogenous day-to-day variation in wet-bulb temperature within districts, we find that a day with wet-bulb temperature of at least 28 °C relative to a day in the reference bin [24 °C, 26 °C), raises the number of daily claims by 3.5%, total disbursements by 4%, and the likelihood that a district records an in-hospital death on a given day by 3.52 percentage points. Utilization is flat across cooler temperatures and rises steeply once wet-bulb temperature exceeds roughly 26 °C. Aggregated over a year, extreme-heat days add about 2.4% to program disbursements -- a lower bound on the fiscal burden. Dry-bulb temperature yields a gradient of the opposite sign, because the hottest ambient days fall in the dry pre-monsoon while physiological stress peaks in the humid monsoon. Studies relying on dry-bulb temperature in monsoonal settings may therefore recover sign-reversed estimates and understate the health costs of a warming climate.