Heat exposure leads to physiological and cognitive impairments that increase the risk of injuries in the workplace, according to an analysis of an OSHA study on heat and workplace injuries in the United States. The analysis assessed injury patterns from heat by industry sector and in states both with and without workplace heat standards.

The study, which was published in the journal Environmental Health, found that exposure to heat affects worker vigilance, coordination and judgement—all critical skills for electrical construction. It can also lead to heat illness, heat exhaustion and heat stroke, which can be life-threatening, according to the Mayo Clinic.

Starting in 2024, businesses in high-hazard industries with 100 or more employees were required to send detailed injury records for the previous year to OSHA’s Injury Tracking Application. High-hazard industries include agriculture, construction, manufacturing and healthcare.

The risk of workplace injury increases with a rising heat index, according to the analysis. Approximately 1.18% of all injuries in 2023 were attributed to heat exposure on days exceeding a heat index of 70°F, according to the analysis.

Researchers found that an upward trend of workplace injury started around 85°F and accelerated above 90°F. The results were consistent across almost all industry sectors, including ones that are predominantly indoors, the analysis said. When the heat index reached 110°F or higher, the odds of workplace injury increased by 9% in states with occupational heat rules and by 22% in states without these safety standards.

Climate change increases the frequency, intensity and duration of extreme heat events, heatwaves and prolonged excess heat conditions, according to a World Health Organization (WHO) factsheet. This, in turn, raises the risk of heat-related injuries in the workplace.

WHO describes heat as an environmental and occupational health hazard. “Heat will reduce working productivity and increases the risk of accidents,” the factsheet said. “It is difficult to complete work … in very hot weather. Heatwaves can also be associated with hazardous air pollution events.”

The risk of heat-related injury can be lowered with proper workplace heat safety regulations that protect workers from heat exposure, the study found.

Florida, Texas and the city of Phoenix recently passed laws that prevent or prohibit local governments from mandating water breaks for outdoor workers, which can put workers in dangerous situations, according to an article in Construction Dive. The American Civil Liberties Union (ACLU) and some cities have sued over the laws.

To lower the risk of heat-related workplace injury, the analysis encouraged employers to put heat safety measures in place such as sufficient time to rest, providing water and shade and creating clear heat plans. Occupational safety training must also explicitly warn about the role of heat in workplace injuries, the analysis suggested.

OSHA is developing a heat safety standard, which will include guidance to protect workers from heat illness. The proposed rule will require employers to implement plans such as access to water, rest and shade. It will also require specific actions that are triggered at heat index levels of 80°F—providing water, rest areas and acclimatizing new workers—and 90°F— implementing mandatory paid breaks, monitoring for heat illness symptoms and providing a written heat injury and illness prevention plan.

Other heat-related resources include a new report from the WHO and World Meteorological Organization providing guidance to protect workers from increasing heat stress. The WHO also has a “Beat the Heat” initiative, which aims to protect the health and safety of workers and spectators at workplaces, sporting and other mass gathering events.