How to keep your indoor air safe from outdoor wildfire smoke
Building scientists who studied air quality in Portland during the 2020 wildfires share tips for keeping indoor air clean and safe when faced with smoke outside.
PORTLAND, Ore. — Oregon is facing extreme wildfire conditions this weekend, and in addition to several planned power shutdowns for public safety, communities across the state are already seeing their air quality impacted by smoke from ongoing wildfires.
Most Portlanders remember how bad it can get when smoke from wildfires drifts here. At one point during the September 2020 wildfire season, the city’s air quality index (AQI) was measured as the worst in the world and health officials recommended everyone to stay indoors.
Chrissi Antonopoulos, a building scientist at Pacific Northwest National Laboratory in Richland, Wash., used data from Portland’s 2020 experience to study effective ways to ensure the air inside homes remains safe to breathe, even when smoke levels outside become dangerous .
“What we saw was that when the smoke event outside was very strong, the introduction of the portable air purifier drastically reduced the amount of particulate matter inside,” she said.
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That means a portable air purifier with a HEPA filter is your best bet, but it’s important to choose one with a high enough Clean Air Delivery Rate (CADR) to fully cover the room it’s placed in. The Environmental Protection Agency (EPA) maintains a bulletin on installing air purifiers.
“We get a lot of infiltration through the leaks and cracks in our house, so sealing those is also very important,” Antonopoulos said.
Tightly closing doors and windows is a must. And residents who choose to run window air conditioners should make sure they’re set to circulate indoor air, rather than sucking in the not-so-fresh air from outside.
For homes with central heating and cooling, another important step is upgrading the main filter. Filters are rated on the Minimum Efficiency Reporting Values (MERV) scale from 1 to 16. The higher the number, the more effective the filter is at removing small particles from the air.
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A filter rated MERV-13 or higher is best for removing smoke from indoor air. It is important to follow the manufacturer’s recommendations as not all core systems can handle the highest MERV rated filters.
But even going from a MERV-8 to a 10 can bring some benefits.
“Even when heating or cooling isn’t needed, keeping your system’s fan running all the time helps filter the air in your home,” Antonopoulos said. “We spend about 90% of our time indoors, and unlike the outdoor environment, the indoor environment is completely unregulated.”
Sealing homes and investing in air filtration are good measures any time of year and can help protect residents from pollen and dust to viruses and germs. But heading into the weekend with the potential for dangerous wildfire smoke, it’s even more important to be prepared.
Chris McGinness is a meteorologist and reporter for KGW. Have an idea for a story or a great photo you’d like to share? Email him at [email protected] or contact Facebook , Twitter and Instagram