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A Duty to Prevent Heat Illness

June 29, 2026 | BCSP Staff Guide

A Duty to Prevent Heat Illness

Exposure to environmental heat hazards resulted in an estimated average of 3,793 days away from work, restricted duty, and job transfer (DART) cases per year in the U.S. between 2021 and 2024, according to the Bureau of Labor Statistics (BLS). The BLS also reported that, in that same time, exposure to environmental heat resulted in an average of 48 fatalities per year.

Where heat hazards pose a risk to workers’ safety and health, employers are responsible for ensuring those workers remain unharmed. Covered as part of the OSH Act’s General Duty Clause, the Occupational Safety and Health Administration (OSHA) is increasingly focused on heat hazard mitigation measures.

In response to the persistence of heat-related injuries and illnesses among workers, OSHA recently updated and extended the National Emphasis Program (NEP) on Outdoor and Indoor Heat-Related Hazards. In its initial run, the number of heat-related inspections OSHA conducted rose from an average of about 200 per year between 2015 and 2020 to approximately 7,000 heat-related inspections between April 2022 and December 2024. The NEP was renewed in April 2026.

The NEP outlines how OSHA will continue monitoring for conditions that could lead to heat-related illness or death:

Compliance safety and health officers (CSHOs) who are investigating workplaces for other purposes will expand their inspection or refer a heat-related inspection for any hazardous heat conditions where there is evidence (in records, employee statements, or CSHO observations).
CSHOs engaged in inspections on heat priority days, when the heat index for the day is expected to be 80°F or more, will inquire regarding the existence of any heat-related hazard prevention programs.
Programmed inspections of high-risk industries will occur on any day that the National Weather Service (NWS) has announced a heat warning or advisory for a local area.

This renewal of the NEP on Outdoor and Indoor Heat-Related Hazards comes as OSHA also endeavors to create a formal rule for Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings. There are strong similarities between what is outlined in the two initiatives, and though the rulemaking process is currently paused, safety leaders can use the proposed rule as guidance. Assessing your organization’s policies and procedures with the proposed rule as reference is one way safety leaders might ensure they meet standards while building a safety program that exceeds them.

As currently written, the proposed rule requires:

1. Heat hazards be identified by:

a. Monitoring heat conditions via weather forecasts or direct measurement of the heat index or Wet Bulb Globe Temperature (WBGT) where work is performed outdoors,
b. Monitoring temperatures indoors where workers are, or are potentially, exposed to sources of heat, and
c. Maintaining this data for a minimum of six (6) months.

2. Developing a Heat Injury and Illness Prevention Plan (HIIPP) that:

a. Includes policies and procedures for controlling heat, and
b. Is specific to, and implemented at, all indoor and outdoor sites.

3. Implementing specific control measures where the temperature exceeds 80°F, to include providing:

a. Drinking water or another source of hydration,
b. Break areas with cooling measures,
c. Acclimatization procedures for new or returning employees, and
d. Paid rest breaks if required to keep workers from overheating.

4. Implementing specific control measures where the temperature exceeds 90°F, including:

a. Reminding workers of HIIPP policies and procedures,
b. Requiring workers to take a 15-minute break every two (2) hours,
c. Monitoring employees for heat illness symptoms, and
d. Posting warning signs in indoor areas with ambient temperatures exceeding 120°F.

5. Developing a heat emergency response plan.

6. Providing related training on heat illness for safety coordinators, supervisors, and other employees.

A foundational document for both the NEP and the proposed rule, the NIOSH Criteria Document, Criteria for a Recommended Standard: Occupational Exposure to Heat and Hot Environments, also provides useful guidance for preventing heat illness and fatalities that could be used to further mitigate heat illness. A summary of General Controls for environmental heat based on this publication is included in the NEP document’s appendices.

The controls recommended in that summary include, but are not limited to:

1. Engineering Practice Controls

a. Use air conditioning

b. Increase general ventilation

c. Provide cooling fans

d. Run local exhaust ventilation where heat is produced (e.g., laundry vents)

e. Use reflective shields to block radiant heat

f. Insulate hot surfaces (e.g., furnace walls)

g. Stop leaking steam

h. Provide shade for outdoor work sites.

2. Administrative and Work Practice Controls

a. Schedule hot jobs for cooler parts of the workday; schedule routine maintenance and repair work during cooler seasons of the year when possible.

b. Provide adequate, cool drinking water on the worksite that is easily accessible and permit employees to take frequent rest and water breaks.

c. Use relief workers and reduce physical demands of the job.

d. Use work/rest schedules.

e. Allow new workers and those returning from extended absences to adjust to hot working environments by gradually increasing their workload.

3. Personal Protective Clothing and Equipment

a. Hats for work outdoors in the sun.

b. For indoor work, loosely worn reflective clothing designed to deflect radiant heat, such as vests, aprons, or jackets.

c. Cooling vests and water-cooled/dampened garments may be effective under high-temperature, low-humidity conditions. However, be aware that cooling vests can become insulating once they reach body temperature.

d. In environments where respirator use is required, consult an industrial hygienist to determine appropriate clothing to prevent heat stress while still protecting workers.

OSHA’s renewed focus with the NEP on Outdoor and Indoor Heat-Related Hazards, the proposed rule, and the extensive resources provided by NIOSH and other organizations all reinforce a common message: the causes of heat-related injuries and fatalities are known, and harm to workers is preventable. Rather than wait for regulatory requirements, safety leaders have an opportunity to strengthen their heat illness prevention programs now, improve organizational resilience, and build a culture that protects workers’ well-being in increasingly challenging environmental conditions.

For more tools and information on preventing heat-related hazards, such as using smart tools like the AIHA Heat Stress App, visit Heat Stress Resources on The HUB.

Tags: General Duty Clause, Heat Illness, Heat Stress, NIOSH, OSHA,