Table of Contents

Introduction

The Division of Occupational Safety and Health of California (Cal/OSHA) has adopted detailed temperature regulations to safeguard workers from heat illnesses in:

  • Outdoor workspaces
  • Indoor work environments

These rules are some of the strictest heat illness prevention standards in the U.S., with precise requirements that differ depending on the work environment and temperature levels.

California's Heat Illness Prevention Framework

California has two main heat illness prevention regulations:

  • Section 3395 for outdoor industries (in effect since 2005)
  • Section 3396 for indoor industries (in effect from July 23, 2024)

The two pieces of legislation complement each other to cover workers in all types of environments where exposure to heat is dangerous.

Indoor Heat Illness Prevention (Section 3396)

Temperature Thresholds and Applicability

The indoor heat standard applies to all interior working spaces where temperatures are 82°F or greater when workers are present. Indoor workplaces are areas below a ceiling that limits air movement and are enclosed by walls, doors, windows, or other obstructions that limit air movement.

Stronger requirements become effective when one or more of the following conditions exist:

  • Temperature or heat index equals or exceeds 87°F
  • Employees wear restrictive clothing and temperature equals or exceeds 82°F
  • Employees perform high radiant heat work and temperature equals or exceeds 82°F

Major Requirements for Indoor Workplaces

  • Water Provision: Employees must be supplied with fresh, cool drinking water at no cost. A minimum of one quart per employee per hour is required, located close to the workspace and cool-down area.
  • Cool-Down Areas: Employers must maintain cool-down areas below 82°F, large enough for resting employees and protected from sunlight and radiant heat.
  • Temperature Monitoring: Employers must measure and record temperature and heat index values (whichever is higher) when enhanced rules apply. Records must be kept for 12 months.
  • Engineering Controls: Employers must use ventilation, air conditioning, or fans to maintain safe temperatures unless infeasible. Targets are ≤87°F or ≤82°F under special clothing/heat conditions.

Exceptions to Indoor Standards

  • Telework locations chosen by employees and not controlled by the employer
  • Incidental exposures under 15 minutes in a 60-minute period (excluding non-air-conditioned vehicles and shipping containers)
  • Emergency operations directly protecting life or property
  • State and local government-owned correctional facilities

Outdoor Heat Illness Prevention (Section 3395)

Temperature Thresholds

For outdoor workplaces, prevention measures for heat illness start at 80°F and include heightened "high-heat procedures" at 95°F. The outdoor standard covers all outdoor locations of employment, though certain industries are held to further standards.

Core Requirements for Outdoor Workplaces

  • Water: Fresh, pure, adequately cool water for drinking at no cost must be provided by employers. The minimum is one quart per employee for each hour, with effective replenishment practices during the course of the shift.
  • Shade: Shade is required when temperatures are more than 80°F and must be provided for all employees on rest breaks. Shade must also be provided upon request when temperatures are less than 80°F.
  • High-Heat Procedures: At or above 95°F, specific industries (agriculture, construction, landscaping, oil and gas extraction, and certain transportation sectors) must implement:
    • Increased communication systems
    • Increased employee monitoring (up to 20 employees per supervisor)
    • Designated emergency contact personnel
    • Reminders for regular water intake
    • Pre-shift safety meetings
  • Agricultural-Specific Provisions: At 95°F or higher, employers in agriculture must ensure workers take at least a 10-minute cool-down rest every two hours.

Universal Requirements Applicable Under Both Standards

Emergency Response Procedures

  • Good communication systems for calling supervisors or emergency services
  • Quick response measures for symptoms of heat illness
  • Procedures for extreme heat illness (e.g., reduced consciousness, staggering, vomiting, disorientation)
  • Clear instructions to workplaces for emergency responders
  • Ban on isolating symptomatic employees or sending them home without appropriate attention

Acclimatization Requirements

New hires and those newly placed in hot work sites must be closely monitored during their initial 14 days. All employees need supervision during heat waves (when temperatures are at least 80°F and at least 10°F higher than the average of the prior five days).

Training Requirements

Both employees and supervisors must be trained on:

  • Environmental and individual risk factors for heat illness
  • Company policies for adherence
  • Need for regular intake of water (up to 4 cups an hour)
  • Types of heat illness, symptoms, and first aid measures
  • Emergency process and reporting requirements

Written Heat Illness Prevention Plans

Employers must develop and maintain written Heat Illness Prevention Plans in English and the primary languages spoken by their employees. These plans should include:

  • Water provision procedures
  • Shade and cool-down area access procedures
  • High-heat procedures (for outdoor settings) or assessment/control measures (for indoor settings)
  • Emergency response procedures
  • Acclimatization methods

Additional Temperature Requirements Under Wage Order 15

California Industrial Wage Commission Order 15 outlines additional temperature comfort requirements for certain indoor environments such as retail distribution and e-commerce warehouses:

  • Reasonable comfort temperatures per industry standards
  • Minimum 68°F in restrooms, toilet rooms, and changing rooms during use
  • Heated rooms at 68°F minimum for employees working in environments below 60°F

Enforcement and Penalties

Cal/OSHA strongly enforces heat illness prevention standards. In December 2024, it issued a $276,425 citation to a landscape maintenance firm for willfully violating these protections.

Current Cal/OSHA Penalties (Effective January 2025):

  • General and regulatory violations: Up to $16,285
  • Serious violations: Up to $25,000
  • Willful and repeated violations: Up to $162,851
  • Minimum willful violation penalty: $11,632

Implementation and Compliance Considerations

For Indoor Workplaces

Because the indoor standard became effective immediately in July 2024, indoor employers with work areas reaching 82°F must:

  • Evaluate existing conditions and determine areas affected by the regulation
  • Create or revise Heat Illness Prevention Plans
  • Provide temperature monitoring systems for greater requirement areas
  • Implement engineering controls where possible
  • Train staff and management on updated requirements
  • Provide cool-down spaces to regulatory standards

For Outdoor Workplaces

Employers need to be in continuous compliance with promulgated outdoor standards:

  • Check weather conditions daily when warm weather prevails
  • Implement high-heat policies at 95°F for covered industries
  • Have proper water and shade supplies available
  • Regular monitoring of employees during periods of high risk
  • Record training and procedures in preparation for Cal/OSHA inspections

Best Practices for Compliance

  • Engineering Solutions: Favor permanent engineering controls like air conditioning, ventilation systems, and heat shields over temporary solutions.
  • Administrative Controls: Establish work/rest schedules, job rotation, and reduced work hours during times of high heat.
  • Personal Protective Equipment: Issue cooling vests, water-cooled clothing, or other personal heat-protective clothing when engineering and administrative solutions fall short.
  • Employee Engagement: Engage workers and union representatives in designing and implementing measures to prevent heat illness, as mandated by the indoor standard.

Conclusion

California's heat illness protection regulations are an all-inclusive effort to safeguard employees from temperature-related injury. With indoor requirements now fully implemented in combination with existing outdoor regulations, employers have a responsibility to thoroughly examine their operations and put suitable control measures in place to ensure compliance and safeguard employee health and safety.

The large fines for non-compliance emphasize the value of proactive compliance and the establishment of strong heat illness prevention programs specific to the conditions of a given workplace.