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December 4, 2023

Heat Stress: Combatting the Silent Killer in the Workplace

Worker drinking water in the heat

Handling Heat Stress Hazards

The summer of 2023, which The National Aeronautics and Space Administration (NASA) recently announced to be Earth’s hottest summer since global records began in 1880, has come to an end. As we transition into cooler months, the feeling of the unrelenting sun, perhaps as we walked across an asphalt parking lot to our air-conditioned car, likely lingers in our memory. For many workers throughout the United States (U.S.), the feeling of laboring in the heat, dehydrated, and to the point of exhaustion, is likely a vivid and painful memory.

For some, they may even be reminded of the co-workers they lost due to heat stroke. According to the U.S. Department of Labor’s Bureau of Labor Statistics (BLS), since 2011 there have been 436 documented heat-related deaths caused by environmental heat exposure among workers in the United States. However, according to The National Institute for Occupational Safety and Health (NIOSH), the total number of heat-related illnesses and fatalities is ultimately unknown, as heat-related events are oftentimes not recognized and the cause of death is frequently listed as a heart attack, rather than exposure to a heat-related hazard.

Research suggests there may be more heat-related deaths occurring in the workplace than recorded. A 2022 study conducted by researchers at the University of Connecticut found that 91.9% of 1,682 severe exertional injuries that were reported to the Occupational Safety and Health Administration (OSHA) between 2015 and 2022 were heat related, as well as 87.6% of the 4,598 exertion-related fatalities investigated by OSHA between 2017 and 2020.

It’s important to note the study only looked at reported injuries (defined by OSHA as an injury resulting in in-patient hospitalization, an amputation, or a loss of an eye) and fatalities. Many heat-related injuries occurring at workplaces in the US may not be severe enough to be reported to OSHA. However, that does not mean their impacts, both to the worker and their employer, are unsubstantial.


What is Heat Stress?

Heat stress, which in recent years has been referred to as “the silent killer,” occurs when the buildup of heat in the body cannot be removed by natural mechanisms, such as convection and evaporation (i.e., sweating). When physical work is performed in conditions with high ambient heat, especially when combined with humidity and inadequate cooling, heat stress may occur. Heat stress can be manifested in several ways. Employees may experience heat rash, heat cramps, heat exhaustion, which can result in symptoms including profuse sweating, weakness, loss of appetite, nausea, and vomiting, and heat stroke.

Common symptoms of heat stroke include extremely high body temperature (104°F-105°F or higher) and rising, shortness of breath, nausea and vomiting, seizures, disorientation, hot, dry skin, and coma. If employees are exhibiting heat stroke symptoms, medical attention must be provided immediately, as fatalities are possible.

Employees working in agriculture are especially vulnerable to heat stress, as they oftentimes spend hours each day working outside. Employees working in buildings with heat-producing equipment, such as ovens, as well as employees who perform moderate or higher physical activity, or wear heavy or bulky clothing or equipment, are also at a high risk of heat stress. Further, those working in hot environments are at a higher risk of injury, as heat may result in sweaty palms, fogged up safety glasses, dizziness, and reduced brain function.

Heat exhaustion vs. heat stress comparison

To prevent heat illness, employers can ensure their employees are protected from occupational heat hazards. To do so, companies can develop and implement heat stress prevention programs, provide effective training to employees, provide time for acclimation of new and returning workers among other measures, and know the signs of heat stress. (NIOAA/Special Graphic) 


OSHA’s National Emphasis Program on Heat-Related Hazards

OSHA recognizes that occupational exposure to heat is a serious hazard. Recently, the agency implemented a National Emphasis Program (NEP) to protect employees from heat-related hazards and resulting injuries and illnesses in outdoor and indoor workplaces. The goal of the NEP, which became effective on April 8, 2022, is to encourage early interventions by employers to reduce heat stress hazards. To achieve this goal, OSHA is conducting targeted enforcement inspections and compliance assistance and outreach activities related to heat-related hazards in the workplace.


Finding Help

Ultimately, employers must ensure their employees are protected from occupational heat hazards. To do so, companies must develop and implement heat stress prevention programs, provide effective training to employees, provide time for acclimatization of new and returning workers, and provide unlimited cool water, access to shaded or cool areas, and scheduled rest breaks for employees.

When it comes to heat stress, prevention is key. Fortunately, there are numerous resources available to employers to help them develop and implement heat stress prevention programs. In addition, tools and applications have been developed to aid supervisors and managers in monitoring environmental conditions in the workplace. For example, The OSHA-NIOSH Heat Safety Tool Application is a resource that provides the forecasted and current heat index and its associated risk level.

The Safety, Health, and Environmental Services (SHES) unit at Georgia Tech is actively working to support small and medium-sized businesses in Georgia with the development of their heat stress prevention programs. Companies can request free and confidential safety and health consultations here.

You can also find heat stress training lesson plans, training guides, and a template for a heat stress prevention program under the “Resources” tab here.


Written by: Rachel González, Safety Consultant

Georgia Tech, Safety, Health, and Environmental Services (SHES)

Rachel González provides occupational safety consulting services for small to medium-sized businesses in Georgia through the OSHA 21(d) Consultation Program at Georgia Tech. Most recently, Ms. González was awarded a Susan Harwood Targeted Topic Training Grant from the Department of Labor to develop and provide training on temperature extremes in the workplace.