As temperatures rise, so does the risk of heat illness—a serious and potentially fatal condition that threatens workers across nearly every industry. Whether you’re an EHS professional managing a worksite or an employee working in hot conditions, understanding heat illness is the first step to preventing it.
What Is Heat Illness?
Heat illness is a spectrum of conditions that occur when the body can no longer regulate its internal temperature. In the workplace, it ranges from mild heat cramps and heat exhaustion all the way to life-threatening heat stroke. Contributing factors include high air temperature, humidity, direct sun exposure, physical exertion, and inadequate rest or hydration. Certain medications and pre-existing health conditions can also increase a worker’s susceptibility.
Being able to recognize the warning signs, such as heavy sweating, dizziness, nausea, rapid heartbeat, confusion, or loss of consciousness, is important for providing timely response and preventing symptoms from worsening.
The Regulatory Landscape
Heat illness prevention is addressed at both the federal and state levels.
Federally, the Occupational Safety and Health Administration (OSHA) launched an updated National Emphasis Program (NEP) for Outdoor and Indoor Heat-Related Hazards, effective April 10, 2026, focusing on inspections and outreach in industries with higher risks of heat-related hazards. OSHA is also developing a dedicated Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings standard (public hearings concluded in 2025; a final rule is pending). In the meantime, employers are held accountable under OSHA’s General Duty Clause, which requires providing a workplace free from recognized hazards. OSHA also promotes the National Institute for Occupational Safety and Health (NIOSH) Recommended Heat Standard as a benchmark for best practices.
At the state level, some OSHA-approved State Plans have enacted their own regulations that go beyond federal requirements. Although temperature thresholds for enforcement vary, the rules share common provisions, such as requiring written policies that address heat illness (e.g., Heat Illness Prevention Program), providing sufficient cool drinking water and shade, prescribing rest break frequency and duration, and enforcing acclimatization periods.
- California has two distinct standards enforced by Cal/OSHA. The outdoor standard (Title 8 CCR 3395) is applicable to all outdoor workplaces and imposes progressively stricter requirements as outdoor temperature rises. The indoor standard (Title 8 CCR 3396) applies whenever the indoor temperature or heat index exceed 82°F. Employers with both indoor and outdoor workers must comply with both standards.
- Washington requires employers in general industry, agriculture, and firefighting to address outdoor heat exposure year-round under WAC 296-62-095. The rule is applicable when temperatures reach 52°F for employees wearing non-breathable clothes (e.g., vapor barrier PPE or clothing) and 80°F for employees wearing all other clothing.
- Minnesota takes a unique approach under MN Rule 5205.0110, focusing exclusively on indoor workplaces. Rather than using ambient temperature, Minnesota uses the Wet Bulb Globe Temperature (WBGT) index to set permissible heat exposure limits by workload: 77°F WBGT for heavy work, 80°F for moderate work, and 86°F for light work. The rule also sets minimum indoor temperatures (60°F for heavy work areas, 65°F for light-to-moderate work) and mandates outdoor air supply of at least 15 cubic feet per minute per worker.
- Oregon enforces Heat Illness Prevention rules that cover both indoor and outdoor work whenever the heat index equals or exceeds 80°F. Most industries, including construction and forestry, fall under OAR 437-002-0156. Agriculture is regulated with similar provisions under OAR 437-004-1131.
EHS professionals operating in these states must ensure compliance with the applicable state standard and should note that state standards generally provide greater worker protection than the federal baseline.
Building a Heat Illness Prevention Program
A strong Heat Illness Prevention Program is the foundation of workplace heat safety. The key components are listed below:
- Training workers and supervisors to recognize, report, and respond to heat illness
- Monitoring daily weather forecasts and on-site conditions (heat index, wet bulb temperature)
- Conducting heat hazard assessments to identify high-risk tasks, locations, and populations
- Implementing prevention strategies such as acclimatization schedules for new and returning workers, engineering controls, and administrative controls like rotating shifts
- Establishing emergency protocols for responding to heat-related medical emergencies, including first aid procedures and a chain of communication
Heat illness is preventable with awareness, preparation, and consistent action. By understanding the risks, staying informed about evolving regulations, and implementing a comprehensive Heat Illness Prevention Program, employers and employees can work together to create safer environments. As temperatures continue to rise, prioritizing heat safety is not just a regulatory obligation, but a critical investment in worker health, productivity, and well-being.
If you need support developing a customized Heat Illness Prevention Program tailored to your organization and workforce, contact us.
This blog was written by Mutya Cruz, PhD, a Quality, Research, and Training (QRT) Specialist at Safety Partners.
