Heat Illness Prevention in Indoor Places of Employment

On June 20, 2024, the Occupational Health and Standards Board approved California Code of Regulations, Title 8, section 3396 (§3396). This Cal/OSHA regulation aims to prevent heat illness in indoor workplaces.

This standard went into effect on July 23, 2024. Employers must take steps to protect workers from heat illness in both indoor and outdoor workplaces.

1. Who does the regulation apply to?

It applies to most indoor workplaces with temperatures equal to or greater than 82°F. “Indoor” refers to a space that is under a ceiling or overhead covering that restricts airflow and is enclosed along its entire perimeter by walls, doors, windows, dividers, or other physical barriers that restrict airflow, whether open or closed. All work areas that are not indoor are considered outdoor and covered by the Outdoor Heat Illness Prevention Regulation (Section 3395).  

Indoor workplaces that meet these conditions are subject to rules governing provision of water, access to cool-down areas, assessments, control measures, emergency response, acclimatization, written plan development, training, and supervision.

Exceptions to regulation at UC Davis:

• Places of employment where workers are teleworking that are not under the control of UC Davis.
• Emergency operations directly involved with the protection of life or property.
• Incidental heat exposures where employees experience temperatures between 82°F and 95°F for less than 15 minutes in any 60-minute period (this exemption does not apply to vehicles without air conditioning and shipping container loading and unloading work). With some exceptions, it applies to indoor workplaces with temperatures equal to or greater than 82°F. 

2. When must employers implement ALL the requirements of this Regulation (including temperature assessments and controls)?

When one or more of the following conditions exist:

• The temperature or heat index equals or exceeds 87°F when employees are present (ex. employees working in an indoor cage wash facility where relative humidity is recorded at 60% and the temperature is 84°F, causing the adjusted heat index temperature to exceed 87°F. (See Appendix A of §3396 to review the heat index chart that adjusts the effective temperature for relative humidity). 
• Employees wear clothing that restricts cooling and temperature equals or exceeds 82°F (ex: employees performing asbestos abatement work in full PPE in an unventilated indoor space during a hot summer day).
• Employees work in a high radiant heat area and the temperature equals or exceeds 82°F (ex: employees working in a high-volume kitchen near ovens and stoves).

3. What are the required training elements?

An updated LMS training module which meets requirements of both indoor and outdoor heat illness prevention regulations can be found here. 

Training is required annually for both supervisors and affected employees. Topics covered include environmental and personal risk factors for heat illness, signs and symptoms of the different types of heat illness, the importance of water consumption, methods of acclimatization, employer procedures for responding to signs and symptoms of heat illness, and emergency response procedures. As a supplement to that online training, supervisors must be trained on how to monitor and respond to hot weather reports, if the work area is affected by outdoor temperatures.

4. How can I prepare myself and my staff for the implementation of this new regulation?

1. Share this webpage with all staff who you think may be subject to the regulation.
2. Identify areas where employees will or may be exposed to conditions described in Section 2 above. Measure the temperature and relative humidity in those areas and create a log.
3. If you can reasonably expect workers in your indoor areas to be exposed to high heat, prepare a written plan, which can be a standalone document or incorporated into your IIPP. In addition, workplaces such as office or academic settings, which would not usually be impacted by the regulation other than during emergencies, can use a simplified “indoor only” manual. EH&S has provided the following resources to meet this requirement:
   • Heat Illness Plan Templates
     • Indoor and Outdoor Heat Illness Plan Template (for general use)
     • Indoor Heat Illness Plan Template (for office/academic settings)
4. Ensure employees and supervisors are trained. This can be accomplished using the online training and supplemental instruction as described in Section 3.
5. Schedule a seminar with EH&S. Our Industrial Hygiene team (healthandsafety@ucdavis.edu) will begin offering training seminars to provide support and supplemental training beyond the online training to departments affected by this regulation.
6. Utilize the resources mentioned above and make sure you understand the regulation and your responsibilities.

• What are engineering controls and when must they be used?

• When conditions exist as described in Section 2 of this page, engineering controls must be implemented, if feasible. (Note that the employer or supervisor may assume these conditions to be present without monitoring or documentation in the case of obvious high heat locations.)

  Some examples of engineering controls include:
  - Increasing natural ventilation when outdoor temperatures or heat index is lower than indoor temperature or heat index.
  - Cooling fans or air conditioning.
  - Local exhaust ventilation at heat and/or moisture generating sources.
  - Reflective shields to block heat sources.
  - Evaporative (swamp) coolers.
  - Isolating/insulating heat producing components/materials/machinery.
  
  Supervisors must start with feasible engineering controls, then add administrative controls if those are not enough to reduce the temperature or heat index below the levels mentioned in Section 2. Feasibility is evaluated on a case-by-case basis in the event of a compliance inspection and is based on the nature of the work, size and configuration of the space, and radiant heat sources, among other factors.

• What are administrative controls and when must they be used?
• When engineering controls do not decrease temperatures and/or heat index below the levels described in Section 2 (or are not feasible to implement), administrative controls must be implemented. Examples include:
  - Modifying work schedules.
  - Gradually increasing unacclimatized workers shift length over first one or two weeks of exposure.
  - Require mandatory rest breaks in cooler environments.
  - Schedule work for cooler times of the day/evening.
  - Rotate job functions.
  - Reduce work intensity/speed.
  - Modifying work clothing.
  - Mark radiant heat sources and create exclusion zone.
  - Work in pairs to monitor each other for signs of heat illness
• What is personal heat-protective equipment and when must it be used?
• If engineering controls and administrative controls fail to minimize the risk of heat illness, then personal heat-protective equipment can be used to protect workers from heat exposure. These can consist of simple ice water-soaked garments, specialized water and air cooled garments, heat reflective clothing, and supplied air personal cooling systems.