Emergency Regulation on Protection from Wildfire Smoke

wildfire smoke

This web page provides an overview of Cal/OSHA's emergency regulation to protect workers from wildfire smoke, which went into effect on July 29, 2019.

California Code of Regulations, title 8, section 5141.1 applies to most outdoor workplaces where the current Air Quality Index (current AQI) for airborne particulate matter 2.5 micrometers or smaller (PM2.5) is 151 or greater, and where employers should reasonably anticipate that employees could be exposed to wildfire smoke.

Wildfire smoke is composed of harmful chemicals and tiny particles suspended in the air that present a significant health hazard for workers exposed to it. These particles can irritate the lungs and cause serious or even fatal health effects, such as:

  • Reduced lung function
  • Bronchitis
  • Worsening of asthma
  • Heart failure

Which employers must comply with the emergency regulation?

Employers with workplaces and operations must comply with the full standard when both of the following conditions apply:

  • The current AQI for PM2.5 is 151 or greater, regardless of the AQI for other pollutants
  • The employer should reasonably anticipate that employees may be exposed to wildfire smoke

Which employers are exempt from compliance with the emergency regulation?

Employers with workplaces and operations in any of the following conditions are exempt from complying with section 5141.1:

  • Enclosed buildings or structures in which the air is filtered by a mechanical ventilation system and the employer ensures that windows, doors, bays and other openings are kept closed to minimize contamination by outdoor or unfiltered air
  • Enclosed vehicles in which the air is filtered by a cabin air filter and the employer ensures that windows, doors and other openings are kept closed to minimize contamination by outdoor or unfiltered air
  • The employer demonstrates that the concentration of PM2.5 in the air does not exceed a concentration that corresponds to a current AQI of 151 or greater by measuring PM2.5 levels at the worksite in accordance with Appendix A
  • Employees exposed to a current AQI for PM2.5 of 151 or greater for a total of one hour or less during a shift
  • Firefighters engaged in wildland firefighting

When did the regulation become effective?

The emergency regulation became effective on July 29, 2019. Employers with workplaces where the regulation applies are expected to comply with the requirements when needed.

What does the emergency regulation require?

Section 5141.1 created the following requirements for employers to protect workers from wildfire smoke:

  1. Identification of Harmful Exposures (subsection c) – For worksites covered by the emergency regulation, employers must determine employee exposure to PM2.5 before each shift and periodically thereafter, as needed.
  2. Communication (subsection d) – Employers must implement a system for communicating wildfire smoke hazards in a form readily understandable by all affected employees.
  3. Training and instruction information (subsection e and Appendix B) – For worksites covered by the emergency regulation, employers must provide effective training that includes at least the information contained in Appendix B.
  4. Control of harmful exposures to employees (subsection f) – Employers must reduce workers' exposure to wildfire smoke in the following ways:
    • If feasible, by providing an enclosed location with filtered air so that employee exposure to PM2.5 is less than a current AQI of 151.
    • If that is not feasible or adequate, by relocating to another outdoor location where the current AQI for PM2.5 is lower, changing work schedules, reducing work intensity, or providing more rest periods.
    • With respiratory protective equipment if employers cannot reduce workers' exposure to PM2.5 to a current AQI of 150 or lower.
      • Where the current AQI for PM2.5 is from 151 to 500, employers must provide NIOSH-approved particulate respirators, such as N95 masks, to all employees for voluntary use, and training on the new regulation, the health effects of wildfire smoke, and the safe use and maintenance of respirators.
      • Where the current AQI for PM2.5 is higher than 500, the employer must provide and require employees to use NIOSH-approved particulate respirators that will reduce employee exposure to PM2.5 to an equivalent of an AQI less than 151.

Determining Current AQI and PM2.5 levels

Employers may use the Air Quality Index or their own direct reading instruments to determine employee exposure to wildfire smoke.

Current Air Quality Index (Current AQI) is the method used by the U.S. Environmental Protection Agency (U.S. EPA) to report air quality on a real-time basis. Current AQI is also referred to as the “NowCast,” and represents data collected over time of varying length in order to reflect present conditions as accurately as possible.

The current AQI is divided into six categories as shown in the table below.

Air Quality Index (AQI)
Categories for PM2.5
Levels of Health Concern
0 to 50 Good
51 to 100 Moderate
101 to 150 Unhealthy for Sensitive Groups
151 to 200 Unhealthy
201 to 300 Very Unhealthy
301 to 500 Hazardous

Direct reading instruments: If an employer monitors the PM2.5 levels at the worksite using a direct reading instrument, the employer must do so in accordance with the information contained in Appendix A and is required 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

Additional federal, state, and local government sources for current AQI for PM2.5 information:

When will the emergency regulation become permanent?

The emergency regulation may last for up to one year while Cal/OSHA works to make the regulation permanent to protect employees from exposure to unhealthy levels of wildfire smoke.

For more information, visit the Occupational Safety and Health Standards Board (OSHSB) Protection from Wildfire Smoke webpage.

September 2019