Association Between Work‐Related Hyperthermia Emergency Department Visits and Ambient Heat in Five Southeastern States, 2010–2012—A Case‐Crossover Study

The objective of this study is to assess ambient temperatures' and extreme heat events' contribution to work‐related emergency department (ED) visits for hyperthermia in the southeastern United States to inform prevention. Through a collaborative network and established data framework, work‐related ED hyperthermia visits in five participating southeastern U.S. states were analyzed using a time stratified case‐crossover design. For exposure metrics, day‐ and location‐specific measures of ambient temperatures and county‐specific identification of extreme heat events were used. From 2010 to 2012, 5,017 work‐related hyperthermia ED visits were seen; 2,298 (~46%) of these visits occurred on days when the daily maximum heat index was at temperatures the Occupational Safety and Health Administration designates as having “lower” or “moderate” heat risk. A 14% increase in risk of ED visit was seen for a 1°F increase in average daily mean temperature, modeled as linear predictor across all temperatures. A 54% increase in risk was seen for work‐related hyperthermia ED visits during extreme heat events (two or more consecutive days of unusually high temperatures) when controlling for average daily mean temperature. Despite ambient heat being a well‐known risk to workers' health, this study's findings indicate ambient heat contributed to work‐related ED hyperthermia visits in these five states. Used alone, existing OSHA heat‐risk levels for ambient temperatures did not appear to successfully communicate workers' risk for hyperthermia in this study. Findings should inform future heat‐alert communications and policies, heat prevention efforts, and heat‐illness prevention research for workers in the southeastern United States.