Protecting Outdoor Workers Exposed to Smoke from Wildfires

Please note: This webpage discusses respiratory hazards for outdoor workers such as farm workers and others who work in locations where wildfire smoke can travel. It does not discuss additional respiratory hazards for firefighters and others who work in close proximity to active wildfires.

Smoke from wildfires contains chemicals, gases and fine particles that can harm health. 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.

Determine if there is Harmful Exposure

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

With exceptions, section 5141.1, Protection from Wildfire Smoke, applies to workplaces and operations where the current Air Quality Index (AQI) for PM2.5 particulate is 151 or greater ("unhealthy") 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.

With exceptions, Section 5141.1 requires employers to determine employee exposure to PM2.5 for worksites covered by this section, at the start of each shift and periodically thereafter as needed. This can be accomplished by any of the following methods:

Protect Workers if the Outside Air is Harmful

With certain exceptions, employers must take the following measures to protect workers when the current AQI is 151 or greater:

  • Implement a system for communicating wildfire smoke hazards in a language and manner readily understandable by all employees, including provisions designed to encourage employees to inform the employer of wildfire smoke hazards without fear of reprisal.
  • Training employees according to section 5141.1 Appendix B.
  • Implement engineering controls, when feasible, to reduce employee exposure to PM2.5 to less than a current AQI of 151 (or to the extent feasible if less than a current AQI of 151 cannot be achieved). Examples include providing enclosed structures or vehicles for employees to work in where the air is filtered.
  • Whenever engineering controls are not feasible or do not reduce employee exposures to PM2.5 to less than a current AQI of 151, implement changes to work procedures or schedules when practicable. Examples include changing the location where employees work or their work schedules.
  • Provide proper respiratory protection equipment, such as disposable filtering facepiece respirators (dust masks), other half facepiece respirators, or full facepiece respirators*. See the following webpages and the "Resources" section below for further information on providing respirators to employees.
    • N95 Mask Commonly Asked Questions
    • "Using Disposable Respirators" (in English and Spanish)

      *To filter out fine particles, respirators must be labeled N-95, N-99, N-100, R-95, P-95, P-99, or P-100, and must be labeled as approved by the US National Institute for Occupational Safety and Health (NIOSH). Full facepiece respirators provide at least five times as much protection from fine particles as half facepiece respirators such as filtering facepiece respirators (dust masks).
  • The employer must provide a sufficient number of respirators for employee use on a voluntary basis when the current AQI for PM2.5 is equal to or greater than 151 but does not exceed 500. The employer must require employees to use respirators when the current AQI for PM2.5 is greater than 500.

If Current AQI PM2.5 is less than 151

If the current AQI is less than 151, the employer may provide filtering facepiece respirators (dust masks) to employees or allow employees to bring their own. See the following webpages and the "Resources" section below for further information on providing respirators to employees.


Other Resources

February 2021