Wildfire Smoke

smoky skies

Wildfire smoke is a mixture of gases and fine particles from burning trees and plants, buildings, and other material. The primary concern with exposure to wildfire smoke is that it contains fine solid particles (also known as particulate matter) that are 2.5 micrometers (PM2.5) in size or smaller. These tiny particles are harmful because they can reach deep into the lungs.

Breathing in wildfire smoke can produce harmful health effects, and can impact individuals with certain preexisting health conditions and those who are sensitive to air pollution.

Wildfire smoke may reach our UW campuses and satellite facilities from various areas both inside and outside of Washington state due to the increasing extent of area burned by wildfires each year.

Outdoor worker protections

The Wildfire Smoke emergency rule provides protection for personnel working outdoors for more than one hour who may be reasonably expected to be exposed to wildfire smoke.  The rule identifies two action levels to protect personnel when air quality worsens.

Air Quality Index (AQI) reaches 69

When the AQI is at 69 or higher in the location where outdoor work is occurring, the University is responsible for:

Air Quality Index (AQI) reaches 101

When the AQI is at 101 or higher in the location where outdoor work is occurring, University units must implement exposure controls where feasible. Such controls may include:

  • Providing work and/or rest areas in enclosed buildings, structures, or vehicles where the air is effectively filtered
  • Providing portable air cleaners in enclosed areas
  • Relocating work indoors or to an outdoor location with a lower AQI
  • Changing work schedules so that outdoor work can occur when the AQI is lower
  • Reducing the amount of work that involves physical exertion
  • Providing additional rest periods
  • Monitoring personnel for exposure symptoms; refer to the symptoms list in the frequently asked questions section of this page.

Respiratory Protection

When the AQI is at 101 or higher, the University unit must provide respirators at no cost to personnel exposed to wildfire smoke.

  • Respirators must be NIOSH-approved devices that effectively protect the wearers from inhalation of particles at the 2.5 micrometers (PM2.5) size, such as N95 filtering facepiece respirators (KN95 respirators not allowed).
  • Respirators shall be cleaned, stored, maintained, and replaced so that they do not present a health hazard to the user.

Air Quality Index (AQI) of 177

When AQI reaches 555 

When the AQI reaches 555, the airborne concentration of PM2.5 is 555 or more micrograms of gaseous pollutant per cubic meter of ambient air (ug/m3), UW personnel must be enrolled in the respiratory protection program. Personnel must be provided and are required to wear one of the following respirators equipped with high efficiency particulate air filters:

  1. Loose-fitting powered air-purifying respirator; or
  2. Full-facepiece air-purifying respirator; or
  3. Full-facepiece powered air-purifying respirator; or
  4. Other respirators that are at least effective.

The following items do not provide adequate respiratory protection from wildfire smoke:

  • Surgical masks
  • Cloth face coverings
  • Bandanas
  • Scarves


The Wildfire Smoke emergency rule applies to UW work areas where it is reasonably anticipated that personnel may be exposed to wildfire smoke, with the following exemptions.

The Wildfire Smoke emergency rule does not apply when University personnel are:

  • Inside enclosed buildings or structures in which windows, doors, bays, and other exterior openings are kept closed, except when necessary to open doors to enter and exit
  • Inside enclosed vehicles in which the air is filtered by a properly maintained cabin air filter and that windows, doors, and other openings are kept closed except when it is necessary to open doors to enter or exit (buses, light rail, and other enclosed vehicles used for transit systems where doors are frequently opened to board and deboard passengers are not included under the exemption in WAC 296-62-08510 (2)(b))
  • Exposed to outdoor air with a Air Quality Index (AQI) that is 69 or higher for a total of one hour or less during a 24-hour period
  • Engaged in wildland firefighting

Responsibilities for the protection of outdoor workers

Air quality monitoring

University units may obtain air quality data through any of the following resources:

You may also use the information in Appendix A of WAC 296-62-08585 to collect particulate data. This involves used a direct-reading instrument to collect measurements of PM2.5. EH&S is available for this service if needed.

General precautions

When the AQI is greater than 101, it is recommended that everyone stay indoors and keep windows closed, especially sensitive groups, such as older adults and young children, pregnant women, and those with a breathing or heart condition. Read more information on the health effects of wildfire smoke and tips for protecting yourself on the Centers for Disease Control and Prevention (CDC) Wildfire Smoke webpage and in the frequently asked questions section below.

Check the Environmental Protection Agency AirNow website for a reliable report of the current and forecasted air quality in your area. AirNow provides the daily AQI, a rating of how clean or polluted the outdoor air is, along with any potential health effects and recommended steps to reduce exposure. 

The best way to protect yourself against the potentially harmful effects of wildfire smoke is to reduce wildfire smoke exposure, for example, by seeking clean air shelters and cleaner air spaces. It is recommended to keep windows and doors closed as much as possible to avoid worsening the indoor air quality.

University buildings that use heating, ventilation, and air conditioning (HVAC) systems to filter indoor air typically remove up to 90% of harmful pollutants in wildfire smoke.

In naturally ventilated buildings (buildings without mechanical HVAC systems), the indoor temperatures may rise due to windows being closed. If the room becomes unbearably hot, portable electric fans and air-conditioning units can be used to cool the space. Check with your unit leadership and the building coordinator to ensure that the facility electrical system can meet the energy demand.


Personnel must be trained on information regarding wildfire smoke before work that exposes the individual to AQI of 69 (PM2.5 levels of 20.5 µg/m3) or higher, and at least annually thereafter.

The Wildfire Smoke Safety Training course is available on the EH&S Training webpage.

Services available

During wildfire smoke events that impact UW campuses and facilities, EH&S is available for consultation and may perform a site visit depending on the situation. We are equipped to conduct site measurements for airborne particulate matter concentrations and to provide recommendations.

Visit the Indoor Air Quality page on the EH&S website for more information and instructions for requesting an indoor air quality evaluation.

To request assistance from EH&S please contact us at ehsdept@uw.edu or (206) 543-7388.

Frequently asked questions