Avoiding Heat Illness

Exposure to extreme heat and high humidity can subject employees to physical conditions that can range from uncomfortable to life threatening. This section describes those conditions and the environmental and personal factors that create risk to employees.

All California outdoor workplaces are subject to the heat illness standard. Other places of outdoor employment are subject to both the standard and special high-heat procedures.

Cal/OSHA, per a statutory mandate, began working on draft regulations for an indoor heat illness standard, at the beginning of 2019.1 After a lengthy rulemaking process, including several revisions of the proposed standard, the indoor heat illness standard went into effect on July 23, 2024. The indoor heat standard parallels the outdoor heat standard in many ways, requiring employers to implement control measures at a certain temperature, provide water and cool-down areas, and have response procedures ready if someone shows signs of heat illness. For more information, see Heat Illness Prevention Overview: Outdoor and Indoor Standards.

Heat Illness Prevention Overview: Outdoor and Indoor StandardsHeat Illness Prevention Overview: Outdoor and Indoor Standards
Currently, the heat illness standard applies to all outdoor places of employment. The California Code of Regulations (CCR), Title 8, section 3395 (Heat Illness Prevention) contains the high-heat procedures and the heat illness standard.

Scope and Application: Outdoor Workplace vs. Indoor WorkplaceScope and Application: Outdoor Workplace vs. Indoor Workplace
Under current law, the heat illness standard now applies to both indoor and outdoor places of employment.

Providing WaterProviding Water
You must provide employees with free, ready access to fresh, pure, suitably cool, potable drinking water.

Providing Access to Shade and Cool-Down AreasProviding Access to Shade and Cool-Down Areas
Shade must be present when the temperature exceeds 80 degrees Fahrenheit.

Implementing High-Heat Procedures for Outdoor WorkersImplementing High-Heat Procedures for Outdoor Workers
Employers in specified industries must implement high-heat procedures when the temperature equals or exceeds 95 degrees Fahrenheit.

Assessment and Control Measures for Indoor WorkersAssessment and Control Measures for Indoor Workers
Cal/OSHA's indoor heat illness prevention standard has unique assessment and control measure requirements that do not overlap with the outdoor standard's requirements.

Emergency Response ProceduresEmergency Response Procedures
Employers are required to implement effective emergency response procedures.

AcclimatizationAcclimatization
The body must adapt when working in hotter environments; acclimatization is the process the body undergoes to adjust to increased heat exposure.

Heat Illness TrainingHeat Illness Training
You must provide training before an employee or supervisor begins outdoor work. To comply with the heat illness standard, all employees must be trained on your established policies and procedures.

Documenting Heat Illness Prevention ProceduresDocumenting Heat Illness Prevention Procedures
You must establish, implement and maintain a written Heat Illness Prevention Plan. The plan can be included as part of your IIPP.

Recognizing Conditions That Create Heat IllnessRecognizing Conditions That Create Heat Illness
Employees’ exposure to high air temperature and relative humidity, radiant heat from the sun and other heat sources cause medical conditions that lead to the stages of heat illness.

Recognizing Symptoms of Heat IllnessRecognizing Symptoms of Heat Illness
Heat illness occurs when the body’s temperature control system cannot maintain an acceptable temperature. Under normal circumstances, the body cools itself by sweating.

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