Comparison of health outcomes from heat-related injuries by National Weather Service reported heat wave days and non-heat wave days - Illinois, 2013-2019.

It is predicted that heat waves will increase as climate changes. Related public health interventions have expanded over the past decades but are primarily targeted at health outcomes occurring during heat waves. However, heat adaptation is dynamic and adverse outcomes related to heat injuries occur with moderate increases in temperature throughout the summertime. We analyzed outpatient and inpatient heat related injuries from 2013 to 2019. National Weather Service event summaries were used to characterize reported heat wave days and weather data was linked to individual cases. Despite the higher rate of heat injury on heat wave days, only 12.7% of the 17,662 heat-related injuries diagnosed from 2013 to 2019 occurred during reported heat waves. In addition, the National Weather Service surveillance system monitoring heat related injuries only captured 2.1% of all heat related injuries and 30.6% of heat related deaths. As climate changes and warmer conditions become more common, public health response to moderate increases in temperature during summertime needs to be strengthened as do the surveillance systems used to monitor adverse heat related health events. Improved surveillance systems, long-term interventions and strategies addressing climate change may help mitigate adverse health outcomes attributable to heat related injuries over the summertime.