California’s Indoor Heat Illness Prevention Standard


California is constantly striving to improve its health and safety regulations, evident by the proposed Indoor Heat Illness Prevention Standard, first proposed in 2017. Since 2006, California's Occupational Safety and Health (Cal/OSHA) Department has maintained a Heat Illness Prevention Standard that addresses outdoor heat illness; the Indoor Heat Illness Prevention Standard was created to protect workers from the dangers of working in high indoor temperatures.

As climate change threatens to increase temperatures in arid climates such as California, it is important for employers to understand the severity of both outdoor and indoor heat illness.

What is Heat Illness?

The United States Division of Occupational Safety and Health (OSHA) identifies several heat-related illnesses, including:

  1. Heat Stroke – considered the most serious form of heat-related illnesses.

  2. Heat Exhaustion – how the body responds to a loss of water and salt.

  3. Heat Cramps – caused by the body's loss of water and salt; can be experienced during or after work hours.

  4. Heat Rash – most common symptom of working in hot environments.

Severity of symptoms varies across individuals, with early symptoms including:

  • Fatigue

  • Heavy sweating

  • Headaches

  • Cramping

  • Dizziness

  • Vomiting

Cal/OSHA states that life-threatening symptoms include:

  • High body temperature

  • Red, hot, dry skin

  • Confusion

  • Convulsions

  • Fainting

If these aforementioned life-threatening symptoms are experienced by you or another employee, emergency services should be contacted immediately.

What is the Indoor Heat Illness Prevention Standard?

According to the most recent draft of California's Indoor Heat Illness Prevention Standard, work sites with the following conditions are subject to this rule:

  1. The temperature equals or exceeds 87 degrees Fahrenheit when employees are present; or

  2. The heat index equals or exceeds 87 degrees Fahrenheit when employees are present; or

  3. Employees wear clothing that restricts heat removal and the temperature equals or exceeds 82 degrees Fahrenheit; or

  4. Employees work in a high radiant heat work area and the temperature equals or exceeds 82 degrees Fahrenheit.

This rule is enforceable by Cal/OSHA and may be included within an employer's Illness and Injury Prevention Program (IIPP).

How do I regulate indoor temperatures for my employees?

The draft Standard outlines three (3) main ways employers can regulate indoor working temperatures.

Engineering Controls

These include isolation of hot processes, insulation of hot surfaces, and shielding of workers from hot sources. Additional options include the use of fans, coolers, air conditioners, and ventilation (when outside temperatures are cooler than inside conditions).

Administrative Controls

These controls include employee acclimatization, work schedule rotation, scheduling shifts during cooler times of day, updating work-rest schedules and required clothing, and the use of relief workers. Reducing time and rate of productivity is another option considered to be effective at minimizing risk of heat illness.

Note: The Rule defines acclimatization as the temporary adaptation of the body to work in the heat that occurs gradually when a person is exposed to it. Acclimatization peaks in most people within four to fourteen days of regular work for at least two hours per day in the heat.

Personal Heat-Protective Equipment

This simple control measure should not be overlooked in terms of effectiveness. Equipment includes: water-cooled and air-cooled garments, wet over-garments, heat-reflective clothing, and supplied air personal cooling systems.

How can I prepare for and respond to the possibility of one of my employees experiencing heat illness?

  1. Ensure communication by voice, observation, and electronic means are embedded in your emergency response plan. This ensures that employees can reach a supervisor quickly in a time of emergency.

  2. Understand and be aware of the symptoms of heat illness.

  3. Do not send an employee who is experiencing symptoms of heat illness home without providing on-site or medical emergency services.

  4. Develop and implement clear and precise directions of the work site for medical responders, so they can quickly reach the inflicted employee. Keep these directions in an easily accessible place on-site for all employees.

  5. Communicate to supervisors that new employees should be closely observed for 14 days during the acclimatization period.

  6. Closely observe all employees on days when temperatures are expected to be 10 degrees higher than average daily temperatures.

Employers can spend countless hours and resources developing emergency response procedures to address the health and safety of its employees. However, these efforts are ineffective if supervisors and employees are not actively trained on procedures to protect the health and safety of employees working indoors during the summer months. All work staff should be trained at a minimum one time per year on the site's indoor heat illness prevention procedures and policies before the hot season begins.

KERAMIDA has a multitude of staff members extensively trained on health and safety regulations and procedures, who can both audit your site's health and safety program and provide training to your staff.

Please contact us to find out more information on how KERAMIDA can help your facility. 

Blog Author


Lindsey Popken
Environmental Scientist

Contact Lindsey at