Size distribution, sources and chemistry of ultrafine particles at Barcelona-El Prat Airport, Spain

•Investigated ultrafine particles (UFP) near an aircraft route.•Identified Taxiing as the major source of UFP.•Ancillary pollutants (nitrogen oxides, etc.) were mainly from external sources.•Observed unimodal size distributions from Taxiing (17 nm) and Takeoff (23 nm).•Detected aluminum-UFP, peaking in the Aitken mode. The rapid expansion of the aviation sector raises concerns about air quality impacts within and around airports. Ultrafine particles (UFP, diameter 2-fold) of Fe, Al, Cr, Cu, Mo, Mn, Pb, Ti, and Sb at the airport compared to the UB, with Al exhibiting the most pronounced disparity. Generally, PAH levels were low at both sites, although concentrations were higher at the airport relative to the UB. Overall, this study provides a comprehensive understanding of UFP within a major European airport, identifying the different sources contributing to PNC and PNSD.