Protect Employees From Heat Illness and Injury

AUGUST 6, 2024

Heat illness affects thousands of indoor and outdoor workers each year and can lead to severe illness or death. Last year was the hottest on record, with an estimated 2,300 people dying in the United States of heat-related illness, according to the National Weather Service. So far, we have experienced even higher temperatures in 2024.

Heat-related illnesses occur when workers build up metabolic heat faster than their bodies can release it and cool down. A study by the Occupational Safety and Health Administration (OSHA) found that heat-related deaths frequently occur when employees are new to the job. This is consistent with other studies that found that the failure to help workers acclimate to the heat appears to be the most common deficiency for employers.

How to Acclimate Workers to Heat

Employers should acclimate workers to hot environments by gradually increasing the duration of work in the hot environment. In particular, employers should provide time for workers to become accustomed to the heat when they have been absent from work for more than a few days. New workers — and all workers returning from an absence of more than a week — should begin with 20% of the usual duration of work in the hot environment on the first day, according to the Centers for Disease Control and Prevention (CDC). Workers can acclimate to heat by increasing their duration incrementally by no more than 20% each subsequent day.

During a rapid increase in excessively hot weather, like a heat wave, the CDC says even experienced workers should begin on the first day of work in excessive heat with 50% of their usual duration, 60% on the second day, 80% on the third day, and 100% on the fourth day. Full acclimation might take up to 14 days or longer, depending on individual or environmental factors.

Heat-Related OSHA Inspections

To help address the significant safety issues caused by extreme heat, OSHA has launched a National Emphasis Program (NEP) focused on protecting workers against heat illness and injuries. Through the program, OSHA aims to conduct heat-related workplace inspections before workers suffer from preventable injuries, illnesses and fatalities.

As part of the program, OSHA will proactively initiate inspections for high-risk industries in indoor and outdoor work settings when the National Weather Service (NWS) has issued a heat warning or advisory for a local area. On days when the heat index is 80 F or higher, OSHA inspectors will engage in proactive outreach and technical assistance to help employers keep workers safe on the job. Inspectors will look for and address heat hazards during inspections, regardless of whether the industry is targeted in the NEP.

While on-site, OSHA inspectors may review work-related illness and injury records, interview employees, and determine if the employer has a heat illness and injury program. This program should:

• Include a means to monitor ambient temperature(s) and levels of work exertion at the worksite.
• Provide easily accessible, unlimited cool water.
• Require additional breaks for hydration.
• Schedule rest breaks.
• Provide shaded outdoor areas.
• Provide time for acclimation of new and returning workers.
• Implement a “buddy” system on hot days.
• Include administrative controls (such as earlier start times and employee/job rotation) to limit heat exposure.
• Provide employee training on signs of heat illness and how to report symptoms; first aid; how to contact emergency personnel; heat illness and injury prevention; and the importance of hydration.

The NEP is a Federal OSHA program. State programs may adopt the NEP or come up with similar programs. In this case, employers should follow the programs that provide guidelines for their states.

OSHA has also developed a Heat Illness Prevention Campaign with a streaming educational video, educational and training materials, Heat Safety Tool Smartphone App, and associated graphics to support the campaign.