California indoor heat rule uses separate coverage and control triggers

October 7, 2026

California’s indoor heat-illness standard applies to covered indoor work areas when the temperature reaches 82 degrees Fahrenheit and employees are present. Section 3396 became operative on July 23, 2024. Its scope provisions distinguish basic coverage from conditions that trigger additional assessment and control measures.

APT’s California indoor heat standard tracker record connects coverage thresholds with assessment and control triggers.

Temperature, heat index and radiant heat have different roles

The additional assessment-and-control provisions apply when temperature or heat index reaches 87°F. They also apply at 82°F where workers wear clothing that restricts heat removal or work in a high radiant heat area, as defined by the standard.

The thresholds should therefore be read with the work conditions. A dry-bulb temperature below 87°F does not establish that the additional requirements are inapplicable. Protective clothing, radiant heat and heat index can affect which provisions apply.

The rule contains exceptions, including specified incidental exposures and certain facilities. The incidental-exposure exception has conditions and excludes vehicles without effective air conditioning and shipping containers during loading or related work. Applicability should be determined from the complete subsection.

Connect the written plan to the actual work area

The standard addresses drinking water, cool-down areas, emergency response, acclimatization and training as well as applicable assessment and controls. Its rulemaking history records the adopted rule separately from the earlier proceedings.

APT’s practical interpretation is to identify indoor areas, clothing requirements and radiant heat sources when reviewing the plan. The assessment record should show what was measured and the conditions during the work. That gives supervisors a basis for applying each relevant trigger to the area.

Find related developments in the industrial hygiene regulatory tracker.