For years, California’s heat illness rules applied only to outdoor work. That changed when Cal/OSHA adopted Title 8, Section 3396, the indoor heat illness prevention standard. If you operate a warehouse, distribution center, commercial kitchen, laundry, foundry, bakery, or manufacturing floor anywhere in California, and the temperature inside reaches 82°F, you now have a written-plan obligation and a set of physical controls to back it up. Many employers still have not heard of this standard, and Cal/OSHA inspectors are asking about it on routine visits.
Who Section 3396 Covers
The standard applies to all indoor places of employment where the temperature equals or exceeds 82°F when employees are present. It does not matter whether the heat comes from the weather, from ovens and fryers, from machinery, or from a metal roof with no air conditioning under it. If the thermometer reads 82°F or higher inside, you are covered.
The workplaces I see most often affected in Southern California are:
- Warehouses and fulfillment centers without full climate control
- Restaurant and institutional kitchens
- Commercial laundries and dry cleaners
- Manufacturing, metalworking, and plastics operations
- Loading docks, truck trailers, and shipping containers
- Boiler rooms, mechanical rooms, and attics where maintenance staff work
There are limited exceptions. Incidental exposure, where an employee is in a hot area for less than 15 minutes in any 60-minute period, is not covered. Employees working from home are excluded, as are emergency operations directly involved in protecting life or property. If your workplace has both indoor and outdoor exposures, both Section 3395 and Section 3396 apply, and your written plan needs to address both.
The Two Temperature Thresholds: 82°F and 87°F
The standard works in two tiers, and understanding the difference is the key to compliance.
At 82°F, the baseline requirements apply. You must provide drinking water, access to cool-down areas, cool-down rest periods, emergency response procedures, acclimatization for new and returning workers, training, and a written plan.
At 87°F, additional requirements are triggered. The employer must measure and record the temperature or heat index, whichever is greater, and must assess and implement control measures to reduce the heat. The 87°F trigger drops to 82°F in two situations: where employees wear clothing that restricts heat removal, such as chemical protective suits or heavy uniforms, and where employees work in high radiant heat areas, such as next to ovens, furnaces, or hot process equipment.
This is where kitchens and manufacturing floors get caught. A cook working the line in front of a broiler is in a high radiant heat area, so the measurement and control requirements kick in at 82°F, not 87°F.
Water, Cool-Down Areas, and Rest Periods
The water requirement mirrors the outdoor standard: fresh, pure, suitably cool drinking water, free of charge, located as close as practicable to the work area. Where plumbed water is not available, you must provide enough for every employee to drink at least one quart per hour for the full shift.
Cool-down areas are the indoor equivalent of shade. The area must be kept below 82°F when feasible, must be blocked from direct sunlight and shielded from radiant heat sources, and must be large enough to accommodate the number of employees on a rest break at the same time. A break room that is itself 85°F does not qualify. A small office with air conditioning that only one person can fit into does not qualify either.
Employees must be allowed and encouraged to take a preventative cool-down rest whenever they feel the need to protect themselves from overheating. When an employee takes that rest, you must monitor them, encourage them to stay in the cool-down area, and not order them back to work until symptoms are gone. If an employee shows signs of heat illness, first aid or emergency response must begin immediately.
Measuring Temperature and Implementing Controls
Once the 87°F threshold (or 82°F for restrictive clothing and radiant heat) is reached, you must measure the temperature and heat index and keep those records. Measurements have to be taken where employees actually work, at the times of day when heat is highest, and whenever there is a change that could reasonably be expected to increase the heat, such as a new process or a heat wave. Employees and their representatives are entitled to observe the measurements.
The standard follows the traditional hierarchy of controls. Engineering controls come first: air conditioning, evaporative coolers, ventilation, fans, insulation of hot surfaces, and shielding of radiant sources. If engineering controls cannot get the heat down enough, administrative controls follow: rotating employees, scheduling hot work for cooler hours, adding rest breaks, and reducing work pace. Personal heat-protective equipment, such as cooling vests, is the last resort, not the first.
Cal/OSHA does not require you to air-condition a 200,000-square-foot warehouse. It does require you to evaluate what is feasible and document why you chose the controls you chose.
Acclimatization, Training, and the Written Plan
New employees, employees returning after an absence, and all employees during a heat wave must be closely observed during their first 14 days of exposure. Heat illness is disproportionately an early-days problem, and inspectors know to ask how you handle it.
Training must cover the environmental and personal risk factors for heat illness, your procedures for water, cool-down rests, and emergency response, the importance of acclimatization, the signs and symptoms of heat illness, and the employee’s right to take a cool-down rest without retaliation. Supervisors need additional training on how to implement the plan and how to respond when a worker shows symptoms.
The written Indoor Heat Illness Prevention Plan must be in English and in the language understood by the majority of your workforce, and must be available at the worksite. It can be a standalone document or integrated into your Injury and Illness Prevention Program under Section 3203, but it has to actually exist, and it has to reflect what your facility actually does. A plan downloaded from the internet that talks about shade structures and agricultural crews will not survive an inspection of a food-processing plant.
Common Gaps Cal/OSHA Finds
- No written plan, or an outdoor plan that never mentions indoor work areas
- No temperature or heat index records for hot days
- No identified cool-down area, or one that is not actually cooler than the work area
- Supervisors who have never been trained on the standard
- No acclimatization procedure for new hires in summer
- Radiant heat and restrictive clothing not accounted for, so the 82°F trigger is missed
Each of these is citable. Where heat exposure could realistically cause serious harm, the violation will be classified as serious, and penalties can reach well into five figures per serious violation and higher for willful or repeat violations.
What to Do Now
- Buy a thermometer or heat index meter and take readings on your floor during the hottest part of the day this week.
- Identify every work area at or above 82°F, and flag areas with radiant heat sources or protective clothing.
- Designate and verify a cool-down area that is genuinely below 82°F and large enough for the crew.
- Write or update your Indoor Heat Illness Prevention Plan and integrate it with your IIPP.
- Train all affected employees and supervisors, and document the training.
- Set up a log for temperature measurements and a procedure for acclimatizing new employees.
If you are not sure whether your facility is covered, or you need a written plan that reflects your actual operation rather than a template, McNeil Safety Consulting can assess your heat exposures, draft a compliant Section 3396 plan, and train your supervisors. Learn more about our safety plan writing services or call (626) 546-9384 to schedule a consultation.