If you live near an airport, there might be more than just noise disrupting your day—you could be inhaling mysterious “onion-like” particles from jet engine exhaust. A new study has uncovered bizarre, layered nanoparticles that may help explain why communities near airports often suffer from higher rates of respiratory problems.
Researchers studying emissions from two widely used commercial aircraft engines—specifically, the CFM56 and PW4000 series—identified four types of exhaust particles. One was familiar soot. The other three, including a never-before-seen type with concentric, onion-like layers, were entirely new to science.
Published in ACS ES&T Air, the study reveals that these particles form not directly at the engine nozzle, but further downstream, where real-world exposure happens. Close to the engines, soot accounted for approximately 68% of the emissions. Just 15 meters away, these new particles dominated the plume, accounting for over 99%.
So where do they come from? Scientists believe the culprit is engine lubrication oil, which escapes through a breather vent, vaporizes, and then decomposes in the hot exhaust. The resulting particles are tiny—just 10 to 20 nanometers across—small enough to travel deep into the lungs or even enter the bloodstream.
The findings have significant implications for health, particularly for airport communities that are already vulnerable to ultrafine pollution. Past studies have linked exposure to reduced lung function and increased inflammation, particularly in those with asthma.
Even more concerning: these unusual particles persist even when planes run on cleaner, sustainable aviation fuels. While those fuels cut down traditional soot, they don’t appear to eliminate these oil-derived pollutants.
As airports expand and air travel increases, this discovery reveals a previously overlooked layer of environmental impact, underscoring a pressing need for updated safety standards and emission controls.
