Communities around Sea-Tac Airport exposed to a unique mix of air pollution associated with aircraft
Seattle-Tacoma Airport, USA had about 438,000 flights in 2018. Communities under flight paths and downwind of the airport are exposed to air pollution from the aircraft. Now research from the University of Washington shows that this includes a type of ultra-fine particle pollution, less than 0.1 micron in diameter, distinctly associated with aircraft. A 2-year study “MOV-UP“) looked at air pollution within 10 miles of the airport, and collected air samples at numerous locations between 2018 and 2019. The researchers developed a new method to distinguish between ultra-fine particle pollution from jet traffic and pollution from other sources such as road vehicles, in the particle size and mixture of particles emitted. They found that communities under the flight paths near the airport are exposed to higher proportions of smaller-sized, ‘ultra-ultrafine’ pollution particles, between 0.01 to 0.02 microns in diameter, and over a larger area compared to pollution particles associated with roads. The tiny particles get deep into the lungs, and can penetrate tissues around the body, potentially causing illness, including cancers. Knowing the different signature of ultra-fine particles from aviation will enable local authorities to detect the pollution from aircraft themselves.
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Communities around Sea-Tac Airport exposed to a unique mix of air pollution associated with aircraft
Sea-Tac Airport is the eighth busiest U.S. airport. In 2018, the airport served nearly 50 million passengers and saw 438,391 takeoffs and landings.
Communities underneath and downwind of jets landing at Seattle-Tacoma International Airport are exposed to a type of ultrafine particle pollution that is distinctly associated with aircraft, according to a new University of Washington study, the first to identify the unique signature of aircraft emissions in the state of Washington.
The finding comes from the two-year Mobile ObserVations of Ultrafine Particles or “MOV-UP” study funded by the Washington State Legislature to examine the air-quality impacts of aircraft traffic on communities located within 10 miles of Sea-Tac Airport.
Researchers at the UW Department of Environmental & Occupational Health Sciences and the Department of Civil & Environmental Engineering collected air samples at numerous locations around Sea-Tac Airport over the course of a year between 2018 and 2019.
The research team then developed a new method to distinguish between pollution from jet traffic and pollution from other sources such as roadway traffic. Ultrafine pollution particles are emitted from both sources, but the research team found key differences in the particle size and mixture of particles they emit.
The researchers then mapped each type of emission mixture to show its specific geographic footprint around the airport.
“We found that communities under the flight paths near the airport are exposed to higher proportions of smaller-sized, ‘ultra-ultrafine’ pollution particles and over a larger area compared to pollution particles associated with roadways,” said Edmund Seto, co-principal investigator and associate professor of environmental and occupational health sciences in the UW School of Public Health.
Ultrafine particles are less than 0.1 micron in diameter — 700 times thinner than the width of a single human hair. The research team coined the term “ultra-ultrafine” particles to refer to the proportion of smaller ultrafine particles between 0.01 to 0.02 microns in diameter.
Although this study did not consider the health effects of exposure to roadway or aircraft-related pollution, previous studies suggest smaller pollution particles are more likely to be inhaled and to penetrate the body than larger particles.
Other studies have linked exposure to ultrafine particles to breast cancer, heart disease, prostate cancer and a variety of lung conditions. The Washington State Department of Health is currently preparing a comprehensive literature review of the potential health effects associated with ultrafine particles.
The discovery of the unique signature of aircraft pollution opens up opportunities for follow-up studies, said Michael Yost, professor and chair of the Department of Environmental & Occupational Health Sciences.
“We can now study the specific health effects of aircraft-related pollution, how different neighborhoods may be affected by it and specific interventions that could reduce human exposure to these pollutants,” said Yost, who is also a co-investigator on the study. “We hope to work with state and local policymakers as well as affected communities to pursue these questions.”
The team gathered air samples from fixed locations, including a former elementary school south of the airport and SeaTac Community Center north of the airport. Researchers also collected air samples through mobile monitors mounted on hybrid vehicles that were driven on 11 routes north and south of the airport in time periods that covered all four seasons of the year.
The researchers used data from the Federal Aviation Administration and other sources to track the number and direction of flights, their altitudes and the wind speed and direction, temperature and relative humidity at the airport.
Their analysis showed that roadway air pollution particles consist of relatively larger particle sizes and higher black carbon concentrations. These particles tend to disperse over relatively short distances downwind of major roadways such as Interstate 5 and SR 99, affecting a narrow swath of near-roadway residences and buildings.
In contrast, emissions associated with aircraft consist of the relatively smaller ultra-ultrafine particle sizes and lower black carbon concentrations. Areas exposed to higher levels of aircraft-related particles tend to be larger, meaning more people are potentially affected.
The research team coordinated closely with local governments, community groups and state and federal agencies throughout the two-year project, soliciting feedback on the study design, analysis and next steps.
Sea-Tac Airport is the eighth busiest U.S. airport. In 2018, the airport served nearly 50 million passengers and saw 438,391 takeoffs and landings.
Co-authors include Elena Austin, Jianbang Xiang and Jeffry Shirai of UW Department of Environmental & Occupational Health Sciences; Tim Gould and Sukyong Yun from UW Department of Civil & Environmental Engineering; and co-senior author Timothy Larson, a professor in both departments. This research was funded by the Washington State Legislature.
This release was written by Jolayne Houtz, director of communications for the UW Department of Environmental & Occupational Health Sciences
Statement from the Port of Seattle:
“We are pleased to see the UW MOV-UP Study completed and turned into the Legislature. The Port strongly supports this effort and helped fund this study which we see as critical to advancing the science needed to understand and reduce fine particulate emissions. Our Commission remains committed to reducing the emissions associated with using fossil fuels, and one way to reduce emissions is through the use of lower-carbon transportation fuels. Many of these fuels including renewable diesel and sustainable aviation fuel reduce ultra-fine particulate in addition to greenhouse gases, the pollution that causes global warming. For this reason, we continue to urge the Washington State Legislature to move quickly towards statewide progressive carbon policy that encourages the adoption of low-carbon transportation fuels. That kind of policy framework could generate real progress on the full-scale implementation of sustainable fuels at the state’s airports and seaports.”
Statement from the Washington State Department of Health:
“Our comprehensive literature review of the potential health effects of ultrafine particle pollution is being completed alongside the UW study. Together, these studies will provide state policymakers and communities with evidence about where and how this type of traffic-related pollution affects people and inform future steps to protect public health,” said Julie Fox, environmental epidemiologist, Washington State Department of Health.
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See also:
Mobile ObserVations of Ultrafine Particles: The MOV-UP study
The Department of Environmental & Occupational Health Sciences (DEOHS) at the University of Washington
DEOHS-led study finds communities around Sea-Tac Airport are exposed to a unique mix of air pollution associated with aircraft
The Mobile ObserVations of Ultrafine Particles (MOV-UP) study analyzed the potential air quality impacts of ultrafine pollution particles from aircraft traffic on communities near and underneath Seattle-Tacoma International Airport (Sea-Tac) flight paths.
This two-year study, which ended in December 2019, was funded by the Washington State Legislature to assess ultrafine pollution particles within 10 miles of the airport in the direction of aircraft flight. The study was led by the UW Department of Environmental & Occupational Health Sciences and the Department of Civil and Environmental Engineering.
UW researchers collected air samples at numerous locations around Sea-Tac Airport over the course of one year between 2018 and 2019.
They found that communities underneath and downwind of jets landing at Sea-Tac Airport are exposed to a type of ultrafine particle pollution that is distinctly associated with aircraft. The study is the first to identify the unique “signature” of aircraft emissions in Washington.
The research team developed a new method to distinguish between pollution from jet traffic and pollution from other sources such as roadway traffic. Ultrafine pollution particles are emitted from both sources, but the research team found key differences in the particle size and mixture of particles they emitted.
The team then mapped each type of emission mixture to show its specific geographic footprint around the airport.
Although this study did not consider the health effects of exposure to roadway or aircraft-related pollution, other studies have linked exposure to ultrafine particles to breast cancer, heart disease, prostate cancer and a variety of lung conditions.
What’s next
We identified three knowledge gaps in the process of analyzing results from this study. These were prioritized as follows by the Study Advisory Board:
Gap 1: What are the health effects of aircraft ultrafine particles?
The potential health effects from aircraft-related particle exposure still need major research. Questions include:
- What are the chemical differences between ultrafine particles from roadway traffic and aircraft sources?
- Are short-term health responses to roadway traffic and aircraft particles different? We could conduct a study of short-term health impacts on sensitive populations, such as pregnant women,
- children, older adults or individuals with pre-existing diseases such as asthma, diabetes and cardiovascular disease.
- Are there long-term health impacts of exposure to traffic and aircraft ultrafine particles?
Gap 2: What can we do to reduce human exposures to ultrafine particles?
Our study suggests that some neighborhoods may have more exposure to ultrafine particles than others due to proximity to roadway traffic and/or overlap with the plumes from aircraft emissions. Questions include:
- How much ultrafine particle pollution infiltrates indoor spaces, particularly schools, daycares, elder care facilities and medical centers where it could potentially expose vulnerable populations?
- What interventions are effective in reducing exposures in these settings? We could design a study that considers the effectiveness of HEPA filtration, whether noise mitigations might alter infiltration or whether LEED buildings or HVAC choices could alter infiltration.
Gap 3: How are exposures to ultrafine particles changing over time?
Roadway and aircraft traffic have changed in volume, travel patterns and per-unit emissions over time and will likely continue to change. Questions include: Are there important daily, seasonal and time trends in exposures? We could design a study to systematically monitor and model the impacts of changing roadway and aircraft traffic on ultrafine particle exposures.
Read the full report about the study’s methodology and findings: Download now
About the partners
Representatives from government agencies, cities and community organisations served on an external Study Advisory Board to provide feedback on the study design, methods and findings. The board included representatives from the following organisations:
Puget Sound Clean Air Agency
US EPA Region X
Washington State Department of Ecology
Public Health—Seattle & King County
Port of Seattle
FAA Northwest Mountain Region
Washington State Department of Health
Quiet and Healthy Skies Task Force
Beacon Hill CHAC
Washington State Department of Commerce
Cities of Burien, Des Moines, Normandy Park, SeaTac and Tukwila
Offices of Representatives Tina Orwall and Mike Pellicciotti, Washington State House of Representatives
Office of US Congressman Adam Smith
Office of US Congresswoman Pramila Jayapal
Contact us
Edmund Seto, PhD, Principal Investigator and Associate Professor, Department of Environmental & Occupational Health Sciences (DEOHS). eseto@uw.edu
Timothy Larson, PhD, Principal Investigator and Professor, Department of Civil and Environmental Engineering and DEOHS. tlarson@uw.edu
Elena Austin, ScD, Research Scientist, DEOHS. elaustin@uw.edu
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https://deohs.washington.edu/mov-up
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