Heat-related illness (HRI) refers to conditions such as heat rash, heat cramps, heat exhaustion, or heat stroke. Heat stroke is a medical emergency that can lead to death if not treated immediately. In some cases, HRI is mild and can be treated with water and cool down rest breaks. In other cases, HRI can be serious, and treatment may require immediate medical attention.
Closely monitor worker if any of the following HRI signs and symptoms occur: 
Heat Rash
- Red clusters on the skin or skin rashes
Heat Cramps
- Heavy sweating
- Muscle pain or spasms
Act fast, stay with worker if any of the following symptoms occur:
Heat Exhaustion
- High body temperature
- Heavy Sweating
- Headache
- Tired or weakness
-
Nausea or vomiting
- Fainting
- Dizziness
Heat Stroke
- Very high body temperature
- Red, dry or damp skin
- Nausea or vomiting
- Headache
- Dizziness
- Confusion
- Unconsciousness
For serious or life-threatening emergencies such as fainting, confusion, or unconsciousness, call 911 immediately. For more information about heat related illness (HRI) signs and symptoms, download Stay Heat-Safe at Work (English, PDF) and Stay Heat-Safe at Work (Spanish, PDF).
Several factors can lead to HRI at work. These include a person not being used to heat (lack of acclimatization), as well as environmental conditions and other risk factors.
Acclimatization: Acclimatization allows the body to gradually adjust to hot conditions. Workers need about 4-14 days to acclimate and build up their heat tolerance. Otherwise, they are more likely to face heat illness.
As an employer, you must monitor employees that are:
- New to a job.
- Starting new tasks in a hot environment.
- Working during heat waves, or in hot areas.
Closely observe your employees within the first two weeks. Monitor them for symptoms to reduce their risk of heat illness.
Environmental Factors: Certain climate and workplace conditions also contribute to heat hazards.
Climate conditions include:
- High temperatures
- High humidity
- Lack of wind or air circulation
- Heat waves
- Direct sunlight
Workplace conditions include:
- Outdoor radiant heat sources at work such as:
- Hot surfaces (black asphalt, metal roofs, or concrete)
- Outdoor Equipment (machines like generators, engines, or large electrical units)
- Personal protective equipment (PPE) or clothing that trap heat
- Operating heavy machinery
Other Risk Factors
Some additional factors may contribute to heat-related illness among workers. This includes:
- Advanced age
- Chronic health conditions or disabilities
- Pregnancy
- Certain medications (examples include stimulants, diuretics, antidepressants and psychiatric medicines)
- Alcohol and other drug use
- Strenuous physical activity during work hours
- Dehydration (not drinking enough fluids)
California employers must follow the California Division of Occupational Safety and Health (Cal/OSHA) regulations to prevent heat-related illness (HRI) in outdoor workplaces. This law, known as the “outdoor heat standard" applies to outdoor workplaces when workers are present. For laws pertaining to indoor workplaces please refer to
California’s indoor heat standard.
A summary of employer responsibilities under the outdoor heat standard follows. However, the summary does not include all provisions. Please read the
law and
Cal/OSHA’s official guidance for all requirements.
Cool Drinking Water
- Provide access to
safe drinking water (PDF, 1.1MB) that is fresh, cool, free of charge, and as close as possible to work areas. Encourage workers to drink water throughout the workday and provide time for them to do so.
Shade Access
- Provide access to
shade when temperatures are greater than 80°F or upon request by employees when temperatures are below 80°F. Shaded area must be:
- Blocked from direct sunlight
- Large enough to accommodate the number of workers on rest breaks so they can sit comfortably
- As close as possible to the work areas
Rest Periods
High Heat Procedures
- Develop and implement High-Heat Procedures for outdoor settings where temperatures reach or exceed 95°F. These settings include:
- Agriculture
- Construction
- Landscaping (excluding fixed establishments with plumbed drinking water)
- Oil and Gas Extraction
- Transportation (excluding air-conditioned vehicle operations without loading/unloading)
- These procedures must include:
- Observing employees for signs of heat illness
- Reminding workers to drink water regularly
- Encouraging cool-down rest periods as needed
Weather
- Train supervisors on how to check and respond to weather forecasts when indoor temperatures are affected by outdoor weather.
Emergency Response
- Provide first aid emergency response to any workers showing heat illness signs or symptoms,
including contacting emergency medical services.
Acclimatization
- Begin a 14-day acclimatization period. Actively monitor employees newly assigned to hot areas, as well as all employees during heat waves.
Training
- Provide trainings for workers and supervisors that include topics about HRI prevention.
Heat Illness Prevention Plan
- Develop and keep an outdoor
Heat Illness Prevention Plan (HIPP) (Word).
- Make sure the HIPP is available in the language understood by the majority of the employees.
- Include procedures for water, cool down areas, rest periods, close observation during acclimatization, prompt emergency response, and heat illness prevention training.