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As California braces for wildfire season, the California Division of Occupational Safety and Health (“CalOSHA”) approved an emergency regulation on July 30, 2019, that requires California employers to monitor air quality for particle pollution, and reduce workers exposure to the potential harmful pollutants from wildfire smoke.

What Is Particle Pollution or Particle Matter?

The Air Quality Index (“AQI”) is calculated for four major air pollutants regulated by the Clean Air Act: ground level ozone, particle pollution, carbon monoxide and sulfur dioxide. The new regulation is aimed at protecting workers from certain particle pollution, also called particulate matter or PM. There are two types of PM – fine particles (2.5 micrometers or less in diameter, referred to as PM2.5) and course particles (particles between 2.5 and 10 micrometers in diameter, referred to as PM10). The new regulation is directed only at the fine particles, or PM2.5, which are produced from all types of combustion, including wildfires. 

How To Check the AQI for PM2.5 At Your Workplace?

One easy way to find the current and forecasted AQI for PM2.5 is to go to and enter the zip code of the workplace. The California Air Resources Board website also displays PM2.5 for California cities here.  Employers can also sign up to receive free email alerts when air quality in their area is forecasted to be a concern.

What Does the Emergency Rule Require?

The new regulation applies to workplaces where the AQI for PM 2.5 is 151 or greater and where employers should reasonably anticipate that employees may be exposed to wildfire smoke.

Under the new rule, employers must take the following steps to protect workers who may be exposed to wildfire smoke:

  • Check the AQI for PM 2.5 before each shift, and periodically thereafter, as needed to protect the health of the employee, to determine if it is at or above 151; and
  • Reduce harmful exposure to wildfire smoke if feasible—for example, by relocating work to an enclosed building with filtered air or an outdoor location where the AQI for PM 2.5 is 150 or lower.

If employers cannot reduce workers’ harmful exposure to wildfire smoke so that the AQI for PM 2.5 is 150 or lower, they must:

  • Provide respirators such as N95 masks to all employees for voluntary use, and
  • Provide training on the new regulation, the health effects of wildfire smoke, and the safe use and maintenance of respirators.

The new rule also requires the employer to establish and implement a system for communicating wildfire smoke hazards in an understandable form that is designed to encourage employees to inform the employer of wildfire smoke hazards at the worksite without fear of reprisal.  The communication system shall include effective procedures for:

  • Informing employees of the current AQI for PM2.5;
  • Informing employees of protective measures to reduce their exposure to wildfire smoke; and
  • Encouraging employees to inform the employer of worsening air quality, as well as any adverse symptoms that may be the result of wildfire smoke exposure, such as asthma attacks, difficulty breathing, and chest pain.

The following workplaces and operations are exempt from the emergency regulation:

  • 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.
  • 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 wildfire fighting

What Should Employers Do Now To Prepare?

  • Employers should familiarize themselves with the various methods for checking the AQI for PM2.5 and determine which method they will use and how they will communicate this information to their employees.
  • Employers should consider acquiring N95 respirator masks if their employees are located in workplaces at risk of higher levels of PM2.5.

Train employees on how to protect themselves and co-workers from the wildfire smoke by: relocating work to enclosed structures or vehicles where air is filtered; changing procedures to move workers to an area with a lower AQI for PM2.5; reducing work time in areas with unfiltered air; increasing rest time and frequency, and providing a rest area with filtered air.