Perron, A.D., Brady, W.J., Custalow, C.B., and Johnson, D.M. (2005). Association of Heat Index and Patient Volume at a Mass Gathering Event. (Abstract only.) Prehospital Emergency Care. 9(1):49-52.
The authors examined the relationship between heat index and the need for medical care during events at a Division I college football stadium located in the southeastern United States. They concluded that for every 10-degree increase in the heat index, three more patients per 10,000 patrons will require care.