When are N95 Masks Required?

Protecting Those Who Work Outside

“Protection from Wildfire Smoke" regulation §5141.1, issued by CA Dept of Industrial Relations in 2019, uses the local air quality index (AQI) for PM 2.5 to determine when worker protections are needed.

AQI: Air Quality Index
PM2.5: solid particles and liquid droplets suspended in air with an aerodynamic diameter of 2.5 micrometers or smaller

If employers reasonably anticipate that employees may be exposed to wildfire smoke, they must:

PurpleAir map example : red or darker = AQI of 150+

1. Monitor the AQI: PurpleAir air quality index map. 
2. Provide training to workers, including how to determine AQI, identify health effects of wildfire smoke exposure, and how to use NIOSH-approved respirators
   See Training Resources below.
3. Establish worker protection procedures, including a plan to reduce worker exposure to wildfire smoke
4. Communicate the above workplace procedures to staff and employees

When AQI is 150 or greater

The employer must provide respirators for employee use on a voluntary basis when the current AQI for PM2.5 is equal to or greater than 150 but less than 500^◊.

Provide proper respiratory protection equipment, such as disposable filtering facepiece respirators (dust masks), other half facepiece respirators, or full facepiece respirators*.

• N95 Mask Commonly Asked Questions
• "Using Disposable Respirators" (in English and Spanish)

N95 Masks

Use N95 masks that are approved for protection from both smoke and coronavirus.

Agricultural operations contact Dept of Ag to obtain masks for your employees: 707-565-2371 SonomaAg@Sonoma-County.org 

* 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 require employees to use respirators when the current AQI for PM2.5 is greater than 500.

Training Resources

To assist employers meet requirements outlined in regulation §5141.1, the Western Center for Agricultural Health and Safety at UC Davis developed the an employer check list and training posters accompanied with discussion guides in both English and Spanish (Linked below). 

• Employer Checklist | Lista de verificación para Empleadores
• Training Poster & Discussion Guide | Guía de Capacitación para Empleadores
• Training Poster| Cartel de Entrenamiento

Additional Information

UCD Western Center for Ag Health and Safety: Wildfire Health Safety

California Department of Industrial Relations: Worker Safety Standards During Wildfire

Californians Turn to Low-Cost Sensors for Highly Local Air Quality Data Air Quality Sensor report by KQED, Nov 2019