Grand Canyon National Park

Exertional Heat-Related Illnesses at the Grand Canyon National Park, 2004–2009

Heat-related illnesses (HRI) pose a significant public health risk to visitors of the Grand Canyon National Park, with nearly 500 nonfatal and six fatal cases reported between 2004 and 2009. The study, analyzing Ranger Emergency Medical Services data, found that 84% of cases involved U.S. residents, primarily hikers aged 43 years on average, with a notable prevalence of cardiovascular conditions (18%). Clinical assessments revealed dehydration (25%), heat exhaustion (23%), and suspected hyponatremia (19%), while 40% required helicopter evacuations. HRI rates peaked in May, underscoring the urgency for targeted prevention efforts, particularly during high-visitation periods.