Long before high temperatures can cause heat illness and even death, heat exposure is linked to subtler impairments in physiological and cognitive performance, according to a new study, “A Nationwide Analysis of Heat and Workplace Injuries in the United States,” published in the journal, Environmental Health. One of the six study authors from Harvard and George Washington University is former OSHA chief Dr. David Michaels.

Research indicates high temperatures can impair hand-eye coordination, cause postural instability, lead to muscular fatigue, and reduce physical reaction times. Cognitive effects of heat include reduced attention, memory, information processing, and overall judgment.

Studies connecting these broader heat-related impairments to workplace injuries in the U.S. have typically used workers’ compensation claims data correlated with temperature data — but no national assessments of work injuries due to heat exist, according to the new analysis. Individual states including California, Washington, and Texas have conducted such studies.

Using 2023 injury case data submitted to OSHA and weather data for the specific injury day, the paper’s analysis shows the odds of suffering a work injury increasing with a rising heat index, with a clear upward trend starting around 85⁰ F and accelerating above 90⁰F.

Heat was found to cause 27,953 excess workplace injuries each year -- traumatic cases such as slips, trips, falls and cuts.

The paper concludes that heat exposure increases the overall risk of work injury in nearly all major industries. Waste management, agriculture, manufacturing, transportation, warehousing and construction were industries with very hot temperature exposures.

The findings indicate that hot temperatures are not just a health concern for heat illness or heat stroke, but also a significant risk factor for a wide number of workplace injuries. These injuries are typically not labeled as “heat-related.” The overall risks of injury were lower in states with workplace rules protecting workers from exposure to extreme heat.

Researchers recommend that occupational safety and health training should clearly warn about the effect of heat on worker awareness, coordination and judgment and the potential for traumatic injuries beyond the well-known heat-related illnesses.

The paper favors an OSHA heat illness prevention standard, currently at the proposal stage. “As climate change intensifies and extreme heat events become more frequent and pervasive, adopting and enforcing comprehensive heat safety regulations will become increasingly important,” the researchers state.