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

Ultrafine particles (UFPs) are a major air quality concern because their small diameter (<100 nm) allows them to reach the lungs' alveolar regions, causing adverse health effects. Civil aviation and airports are important sources of UFPs in urban areas. In this study, a one-month intensive measurement campaign in November 2022, 1 km downwind of Zurich Airport, revealed that high UFP number concentrations up to 300 000 cm^-3 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.