High outdoor temperatures and wildfire smoke events may impact indoor air quality


Updated 8/1/22

UW buildings are typically supplied with a percentage of outside air either via mechanical fans (a mechanical HVAC system), or natural ventilation (e.g., operable windows), depending on each building and system.

  • UW personnel working indoors should keep windows closed as much as possible and rely on the building’s central heating, ventilation, and air conditioning (HVAC) system to provide filtered air during high outdoor heat and wildfire smoke events.
  • UW buildings equipped with mechanical HVAC systems have air filters rated at MERV-13 or higher as recommended by the CDC for COVID-19 prevention and typically remove about 90% of harmful pollutants in wildfire smoke.

In naturally ventilated buildings (buildings without a mechanical HVAC system), the indoor temperatures may rise when windows are closed. If it becomes unbearably hot, portable fans and air-conditioning units can be used to cool the space.

  • To reduce the potential for spreading the virus that causes COVID-19, the airflow should be directed away from the body and face of other people.
  • Check with your unit leadership and the building coordinator to ensure the building’s electrical system can meet the energy demand prior to using a portable air conditioning unit.

Read the "Excessive indoor heat" section of the Indoor Air Quality webpage for additional recommendations.

During a wildfire smoke event when the Air Quality Index (AQI) reaches 69 or above, portable air cleaners with HEPA filtration may be helpful to reduce exposure to wildfire smoke particles in a specific room or space. Refer to the Portable Air Cleaner Selection, Care and Maintenance focus sheet and consult with EH&S as needed.

University units with personnel working outdoors during during high heat and wildfire smoke events should determine whether the Washington state outdoor heat exposure and wildfire smoke rules apply and take action to protect workers. Visit the Wildfire Smoke and Outdoor Heat Exposure webpages for links to resources and required training courses.

Contact EH&S at 206.543.7388 or airquality@uw.edu for more information.