UW News

January 26, 2022

Air pollution from planes, roads infiltrates schools and can be dramatically reduced with portable air filters

UW News

Professor testing air quality

Elena Austin, assistant professor of environmental and occupational health sciences in the UW School of Public Health, sets up testing equipment for a study of air quality in public schools near Sea-Tac Airport.Mark Stone/University of Washington

What started as a University of Washington-led project to measure air pollution near Sea-Tac International Airport has led to schools in the area installing portable air filters to improve indoor air quality.

First, UW researchers found they were able to parse aircraft pollution from roadway pollution in the communities under Sea-Tac International Airport flight paths and map the air quality impacts of the ultrafine particles associated with planes. Then they discovered that the mix of ultrafine particle pollution, black carbon and other pollutants from both sources was infiltrating school buildings in the area.

Alerted that this pollution was getting into schools, community advisors to the study wondered if the UW crew could find a way to remove the pollution and protect children, teachers and workers in those buildings. They were concerned because evidence is emerging that suggests this pollution is bad for everyone’s health, particularly children and older adults. Poor indoor air quality may also lead to poor student performance and increased absenteeism from school.

“It wasn’t clear from the outset of the project that we could measure significant infiltration indoors,” said Elena Austin, assistant professor of environmental and occupational health sciences in the UW School of Public Health. “Not all particles act the same. They don’t behave the same in the brain or in the body, and they also don’t penetrate into buildings through the same routes. However, we did measure significant infiltration.”

Where UW works

The Washington State Legislature established a unique relationship with the UW Department of Environmental & Occupational Health Sciences nearly 60 years ago that continues to support innovative approaches to protect Washington’s workers.

Read more about this UW collaboration

In Phase One of their Healthy Air, Healthy Schools Project, funded primarily by the Washington State Legislature, the UW team discovered that portable air cleaners with HEPA, or High Efficiency Particulate Air, filters in classrooms reduced pollution levels dramatically.

In their recent report to the legislature, the researchers wrote that the filters reduced all ultrafine particles by 83%, aircraft-specific particles by 67% and heavy-duty truck particles by 73% over a two-day test period (see graphic above for more reduction details).

“We have to consider outdoor air pollution when we’re thinking about healthy schools, and the answer to addressing outdoor air pollution is twofold: The first is reducing the emissions from their sources, but that is not always possible. So, when that is not possible, effective interventions are critical. This project demonstrates that HEPA filters can be a viable intervention,” Austin said.

The team’s data was so stark that community advisors encouraged school districts to use these filters in their buildings. In response, Austin said, the two school districts the UW team worked with, Federal Way Public Schools and Highline Public Schools, purchased air filters for most of their classrooms to improve indoor air quality and to combat the spread of the virus that causes COVID-19.

“When many of the school districts we’re working with saw the results and heard concerns from parents, teachers and unions about air quality, they went ahead and used federal funds to purchase HEPA filters for their classrooms,” Austin said.

And all of that was just Phase One of the team’s project.

For Phase Two, the researchers are working on a two-year study in 20 schools across Washington where they will deploy more air filters and learn more about student health and academic performance in classrooms with cleaner air. They also hope to help school districts balance the benefits of these filters with their energy use and explore other methods for reducing air pollution, such as upgrading buildings.

“Our first phase of the study was over a couple of days, so we want to be able to show that over the course of a longer term there’s a significant improvement in air quality when the HEPA filters are deployed. Then, we want to see what benefits that improved indoor air quality has on student health, performance and absenteeism,” Austin said.


Co-authors are Nancy Carmona, Jeffry H. Shirai, B.J. Cummings, Lisa Hayward and Edmund Seto from the UW Department of Environmental & Occupational Health Sciences; Timothy Gould from the UW Department of Civil & Environmental Engineering; and Timothy Larson, a professor in both UW departments.

In addition to funding from the Washington State Legislature and the EPA, regional partners for the study include the cities of SeaTac, Burien, Federal Way, Normandy Park and Des Moines; Federal Way Public Schools; Highline Public Schools; and the University of Washington Ultrafine Advisory Group.

For more information, contact Austin at elaustin@uw.edu.