Jagai, J., Grossman, E., Navon, L. et al. (2017). Real-Time Surveillance of Heat-Related Morbidity: Relation to Excess Mortality Associated with Extreme Heat. PLoS One. 12(9): e0184364.
The authors combined data from emergency medical services (EMS) and emergency department (ED) visits over a period of time in New York City to calculate heat-related mortality. They found a (statistically significant) 7% increase in non-external cause mortality associated with one-day lagged heat-related EMS calls and a 5% mortality increase with one-day lagged ED visits.