How to keep indoor air clean during wildfire season


a person putting weather stripping on their window

The 2020 fire season has been devastating, from the lives lost to the amount of land and structures burned to the many families and communities displaced. Even Oregonians not near an active fire area are likely experiencing the complications of hazardous air quality levels due to these fires.

Wildfire smoke can lead to unhealthy air quality, both indoors and out. Reducing exposure to smoke is important, especially for children, older adults and people with heart or lung disease.

When smokey conditions lead to unhealthy air quality, or if officials advise you to stay indoors, take these actions to reduce your smoke exposure:

  • Keep windows and doors closed. Use fans and air conditioning to stay cool.
  • If you have an HVAC system with a fresh air intake, set the system to recirculate mode or close the outdoor intake damper.
  • If your HVAC system includes a high efficiency filter, run the system’s fan to remove particles from the air. Look for HVAC filters that are rated with a value of MERV 13 or higher to reduce smoke particles in the home.
  • If you have a window air conditioner, close the outdoor air damper. If you cannot close the damper, do not use the window air conditioner. Make sure that the seal between the air conditioner and the window is as tight as possible.
  • If you have a portable air conditioner with a single hose, typically vented out of a window, do not use it in smoky conditions since that can create a negative pressure in the house, which will cause outdoor air to come inside. If you have a portable air conditioner with two hoses, make sure that the seal between the window vent kit and the window is as tight as possible.
  • Use a portable air cleaner or high-efficiency filter to remove fine particles from the air. Run it as often as possible on the highest fan speed.
  • Avoid activities that create more fine particles indoors: smoking cigarettes; using gas, propane or wood-burning stoves and furnaces; spraying aerosol products; frying or broiling food; burning candles or incense; vacuuming, unless you use a vacuum with a HEPA filter.
  • Gas furnaces and direct vent gas fireplaces vent to the outdoors and are safe to use. Switch your furnace to fan or circulate to improve indoor air filtration and install a fresh air filter.
  • You can safely use your gas or electric stove or oven with proper ventilation, such as a range hood. Avoid frying, toasting, broiling or other methods that can create smoke. Consider baking, boiling or microwaving meals.
  • When air quality improves, air out your home by opening windows or the fresh air intake on your HVAC system.

For more information on indoor air quality, check out these resources from the federal Environmental Protection Agency and this video from Multnomah County on how to build your own electronic air cleaner.