Ubiquity of Aviation Ultrafine Particles and Lubrication Oil Compounds Near Zurich Airport

originate solely from aircraft operations. These emissions are either advected downwind of the airport or mixed downward during aircraft landings overhead. The measurements confirm that most aviation-related UFPs are volatile with geometric mean diameters <20 nm. Under certain conditions, they can rapidly grow up to ∼40 nm, while their volatile particle number fraction drops from ∼0.9 to ∼0.1. Online mass spectrometry shows that engine lubrication oil signals closely track aviation-related high UFP levels, enabling attribution of high UFP concentration events to aviation emissions. Multiyear measurements at the site further show that airport emissions dominate daytime UFP concentrations for ∼30% of the time across all wind directions. The widespread presence of UFPs and related organophosphate oil compounds poses a health concern for communities near airports that regulators should address.