Cal/OSHA Wildfire Smoke Regulation

Cal/OSHA Wildfire Smoke Regulation

Article Details

Last Updated

04 April 2024


17 March 2021



In this article, we discuss Cal/OSHA air quality standards aimed at protecting the health and safety of California’s Workers.

Why is wildfire smoke an issue?

Smoke from wildfires contains chemicals and fine particles that can harm a person’s health significantly. The greatest hazard comes from breathing fine particles in the air, which can reduce lung function, worsen asthma and other existing heart and lung conditions, and cause coughing, wheezing, and difficulty breathing.

The smallest, and usually the most harmful, particulate matter is PM2.5. This consists of solid particles and liquid droplets suspended in the air, with an aerodynamic diameter of 2.5 micrometers or smaller.

CAL/OSHA wildfire smoke regulation background and impetus

The Division of Occupational Safety and Health in California (better known as Cal/OSHA) exists to help protect workers from health and safety hazards on the job in almost every workplace in California.

Cal/OSHA’s Emergency Regulation was approved by the Office of Administrative Law. It requires employers to protect workers from hazards associated with wildfire.

On August 27, 2019, Cal/OSHA convened an advisory committee to further discuss the rule. The Occupational Safety and Health Standards Board, a seven-member body appointed by the Governor, is the standards-setting agency within the Cal/OSHA program. The Standards Board’s objective is to adopt reasonable and enforceable standards at least as effective as federal standards. The Standards Board also has the responsibility to grant or deny applications for variances from adopted standards and respond to petitions for new or revised standards.

A year later, on August 20, 2020, Cal/OSHA reminded employers that Section 5141.1: Protection from Wildfire Smoke is still effective. Cal/OSHA’s wildfire smoke standard applies to workplaces where the current Air Quality Index (AQI) for airborne PM2.5 is 151 or greater (deemed an unhealthy level) and where the employer should reasonably anticipate that employees may be exposed to wildfire smoke. Reference section 5141.1 for details on the scope and application of this regulation.

Aeroqual Series 500 wildfires California 2017

Employers responsibilities under the new regulation

Under the new Cal/OSHA air quality standards, employers must take the following steps to protect workers who may be exposed to wildfire smoke:

  • Identify harmful exposure to airborne particulate matter from wildfire smoke at the start of each shift and periodically thereafter by checking the AQI for PM2.5 in regions where workers are located.

  • Reduce harmful exposure to wildfire smoke if feasible. For example, by relocating work to an enclosed building with filtered air or to an outdoor location where the AQI for PM2.5 is 150 or lower.

  • If employers cannot reduce workers’ harmful exposure to wildfire smoke so that the AQI for PM2.5 is 150 or lower, they must provide:

  • Respirators such as N95 masks to all employees for voluntary use

  • Training on the new regulation, the health effects of wildfire smoke, and the safe use and maintenance of respirators

Where can employers check current AQI and forecasts?

Employers can check AQI forecasts and current AQI for PM2.5 from the following web sources:

Employers can also find out the AQI by telephone, email, and text directly from EPA


Employers can measure local PM2.5 levels with a CAL/OSHA wildfire smoke monitor

Ensuring outdoor workers are protected from the effects of wildfire smoke requires hyper-local data you can trust. Monitoring PM2.5 levels with a ‘direct reading instrument’ is the best way to obtain this vital data. Aeroqual Ranger is a real-time, active-sampling monitor that provides simultaneous measurements of multiple particle fractions in a cloud-capable handheld solution. Designed for use by industrial hygienists, consultants, and environmental health and safety (EHS) professionals, Aeroqual Ranger provides real-time air quality data on a range of airborne hazards (including PM2.5). Access accurate data from anywhere using Ranger Cloud and act quickly to protect worker health. To help with your selection, Cal/OSHA has outlined mandatory requirements for employers wanting to use their own wildfire smoke monitor.

The employer must be able to demonstrate that their chosen PM2.5 monitor:

  • Does not underestimate employee exposure to wildfire smoke

  • Is designed and manufactured to measure ≤ 0.3μm to 2.5μm

  • And all necessary accessories are calibrated, maintained, and used, following the manufacturer’s instructions

  • Is used under the supervision of someone with the necessary experience or training in air quality monitoring

Employers need to use the following table to convert the PM2.5 concentration to the AQI for PM2.5:

PM2.5 in Micrograms per Cubic Meter (µg/m3)

Air Quality Index (AQI) Categories for PM2.5

0 to 12.0

0 to 50

12.1 to 35.4

51 to 100

35.5 to 55.4

101 to 150

55.5 to 150.4

151 to 200

150.5 to 250.4

201 to 300

250.5 to 500.4

301 to 500

Aeroqual offer a Cal/OSHA wildfire smoke monitoring kit, created specifically to help employers comply with the Cal/OSHA wildfire smoke regulation and subsequently protect the health of their outdoor workers.

For more on how we can help you protect your workers and meet your obligations under the Cal/OSHA air quality standards, please get in touch.

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