Heat, Humidity, and Infant Mortality in the Developing World

We study how extreme temperature exposure impacts infant survival in the developing world. Our analysis overcomes the absence of vital registration systems in many poor countries, which has been a limiting factor in the temperature-mortality literature, by extracting birth histories from household surveys. Studying 53 developing countries that span the globe, we find impacts of hot days on infant mortality that are an order of magnitude larger than estimates from rich country studies, with humidity playing an important role. The size and implied geographic distribution of harms documented here have the potential to significantly alter assessments of optimal climate policy.