The western United States may be in for another difficult wildfire season in 2021. Such events bring wildfire smoke, a potential health hazard particularly for employees who work outdoors.

Employers in California are required to comply with specific, prescribed obligations under the California OSHA wildfire smoke regulation, the first of its kind in the country. California employers should prepare now to comply with these obligations that may become applicable with little notice, especially as drought conditions continue.

Cal/OSHA’s Wildfire Smoke Regulation

Cal/OSHA’s wildfire regulation was originally enacted as an emergency rule in 2019 and was made permanent in February 2021. Employer obligations under the regulation are triggered by the current Air Quality Index for Particulate Matter with aerodynamic diameter of 2.5 micrometers or smaller, which measures the concentration of wildfire smoke particles in the air.

Employers are required to determine the AQI level at the start of each shift and periodically thereafter as needed to protect the health of employees. Employers can do this by checking websites hosted by the following entities: U.S. EPA AirNow, the Interagency Wildland Fire Air Quality Response Program, the U.S Forest Service, the California Air Resources Board, the local air pollution control district, or the local air quality management district.

Employers can also measure PM2.5 levels at their worksites as provided by Appendix A to the Cal/OSHA wildfire regulation. If the AQI is 151 or greater (i.e., red or purple on the AQI color-coding scheme), then the regulation’s obligations begin to trigger, with more onerous requirements imposed as AQI levels worsen.

Both outdoor and indoor operations are included within the regulation’s scope, although employees exposed to AQI of 151 or greater for an hour or less during a shift are exempt, as are employees in enclosed indoor operations with air filtered by mechanical ventilation systems, so long as the employer ensures that windows, doors, and other openings are kept closed (except for necessary ingress and egress).

Employer obligations under the Cal/OSHA wildfire regulation fall into three categories: exposure control, communication, and training.

Exposure control

If the applicable AQI ranges from 151-500:

  • Employers are required to implement physical or structural improvements (“engineering controls”) whenever feasible, such as providing enclosed structures and improving air filtration.
  • If engineering controls fail to reduce employee exposure to less than a current AQI of 151, employers must implement policy and procedure improvements (“administrative controls”) to protect employees, to the extent practical. Examples of Cal/OSHA-endorsed administrative controls include relocating work to a location where the current AQI is lower, changing work schedules, reducing work intensity, and providing additional rest periods.
  • Employers must provide NIOSH-approved respirators that effectively protect the wearers from inhalation of PM2.5, such as N95 respirators, for all employees for voluntary use. Employers must also encourage employees to use such respirators. Surgical masks or other face coverings like scarves, bandanas, and cloth face coverings are insufficient to satisfy this obligation.
  • N95 respirators that are used on a voluntary basis are not subject to respirator fit testing and medical evaluations typically required under Cal/OSHA Section 5144. Likewise, employers are to provide respirator training outlined in the Cal/OSHA wildfire smoke regulation, Appendix B instead of Appendix D to section 5144 when respirators are used voluntarily.

If the applicable AQI exceeds 500:

  • Employers must mandate respirator use and provide respirators sufficiently effective to reduce the AQI levels inside the respirator to less than 151.
  • Employers must comply with respirator safety obligations in Cal/OSHA Section 5144, including employee fit testing and medical evaluations and having a written workplace respiratory protection program


  • Employers must establish and implement a system that informs employees about current AQI levels and protective measures available to employees to reduce their wildfire smoke exposures.
  • Employers must also encourage employees to let employers know if air quality worsens or if they are experiencing adverse symptoms that may be a result of wildfire smoke (such as respiratory problems).


  • Employers are required to provide their employees with training regarding wildfire smoke hazards. The specific contours of required training are located in the Cal/OSHA wildfire smoke regulation, Appendix B, and include the health effects of wildfire smoke, the right to obtain medical treatment without fear of reprisal, how to obtain the current AQI, information regarding the employer’s communication system, and the employer’s methods to protect employees from wildfire smoke (including the use of respirators).

Wildfires and wildfire smoke are now an annual event, and California employers should plan now for compliance with wildfire smoke obligations before wildfire season. Given the regulation’s significant burdens in worsening AQI circumstances, advanced preparation is especially important for employers who lack a sufficient stock of N95 masks or other appropriate respirators or who may need to continue operations even if applicable AQI readings exceed 500.