Cal/OSHA has an emergency regulation (CCR section 5141.1) to protect employees exposed to wildfire smoke. The regulation requires the following:
a) identification of harmful exposures, b) communication, c) training and instruction, d) control of harmful exposures, and
e) specific particulate sampling requirements if an employer opts to monitor employee exposure with a direct reading instrument.
Employers should be aware that the CCR requirement to follow the "Current AQI" (as found on AirNow.gov)
represents a broad area or county may not represent actual workplace AQI. Site workplace
monitors (such as PurpleAir etc.) are allowed by the CCR might provide better local information but could also be problematic given their data unreliability and that they are not regulatory monitors.
Read the CCR for specific guidance.