The Ambient Temperature and Occupational Safety and Health study (A-TOSH) - Ambient heat poses a critical threat to population health, particularly for workers in industries with high heat exposure—such as construction, manufacturing, and agriculture. These workers face disproportionately high risk of experiencing a range of adverse heat-associated outcomes, including acute cardiovascular and respiratory events, injuries, and death. According to the Bureau of Labor Statistics, heat exposure in the U.S. is associated with over 3,500 workplace injuries and illnesses and 34 deaths annually. However, these figures likely underestimate the true burden due to frequent misclassification of heat-related outcomes. To capture the true burden of occupational heat-related morbidity and mortality, state-of-the-art statistical approaches are required. The impact of heat exposure is likely higher among workers who lack access to factors such as healthcare and safe housing, which influence workers’ ability to withstand and recover from heat stress. Understanding the magnitude of differences in heat exposure and associated health outcomes across these characteristics is essential for designing effective interventions. Existing workplace heat safety protocols provide a useful basis for evaluating whether real-world population health intervention strategies are associated with reductions in heat-related illness and injury in work environments. These protocols vary in their requirements but commonly include measures such as rest breaks, medical monitoring, heat safety training, acclimatization periods, and other practices intended to support worker health and safety. Yet, there is a striking lack of empirical evidence regarding the effectiveness of these protocols for protecting workers from heat-associated mortality or morbidity. Here, we will address critical gaps in knowledge about the burden of occupational heat-related injuries, illnesses, and deaths, as well as the effectiveness of workplace heat safety interventions by: (1) Quantifying the annual burden of heat-related workplace injuries, illnesses, and fatalities from 2003 to 2023 across counties, states, industries, and job titles; (2) Assessing differences in heat exposure and adverse outcomes based wage level, educational attainment, household composition, housing conditions, and worker job category; and (3) Calculating associations of workplace heat safety protocol adoption with rates of heat-related injuries, illnesses, and deaths among laborers. To accomplish these aims, we will leverage advanced statistical methods and nationally representative longitudinal data; develop an open-source database of workplace heat safety protocols; and conduct a robust natural experiment. This study will provide the most comprehensive, high-resolution estimates of occupational heat-related injuries, illnesses, and deaths across the U.S. It will also provide essential empirical data on workplace heat safety protocols as intervention strategies, generating evidence relevant to whether these approaches are associated with improved worker health and safety. This study represents a critically important step toward advancing health and safety in the American workforce.
