Cieniek, BogumiłCieniek, BogumiłPłoch, DariuszBrewka, JuliaKluska, KatarzynaStefaniuk, IreneuszKasprzyk, Idalia2025-11-132025-11-132025https://rdb.ur.edu.pl/handle/item/82Samples of air pollution collected with a Dekati Electrical Low Pressure Impactor (ELPI+, Dekati Ltd., Finland). RAW data: [ELPI-DATA FILE], [E+26517] - ascii file Images from a high-resolution scanning electron microscope SEM Helios 650 Nanolab manufactured by FEI. RAW data: images files. Electron paramagnetic resonance (EPR) measurments on X-band (ν ≈ 9.4 GHz) with modulation of the magnetic field at 100 kHz, by a Bruker multifrequency and multiresonance FT-EPR ELEXSYS E580 spectrometer. RAW data: Bruker B3ST files.This study aimed to verify whether Saharan dust reached south-eastern Poland in spring 2025 and to assess its influence on the chemical composition and oxidative po-tential of particulate matter. Using an ultra-sensitive Dekati instrument, aerosols were measured across fifteen size fractions (6 nm–10 µm), enabling the detection particulate matter even in the finest particles — a feature not previously documented for Saharan dust. Electron paramagnetic resonance spectroscopy was used to quantitatively deter-mine and identify radicals associated with different PM fractions. The analysis revealed a high content of ultrafine particulate matter (<1 µm), which may pose a potential risk to human health. The chemical composition of the particulate matter confirmed the long-range transport of Saharan dust over SE Poland at the beginning of March 2025. EPR measurements indicated a relatively large amount of pollutants that exhibited magnetic properties, which were not detected in the control samples. The use of ad-vanced measurement instrumentation enabled the detection of ultrafine fractions and the identification of free radicals associated with Saharan dust, providing new insight into its oxidative potential and chemical reactivity.enAttribution-NonCommercial-NoDerivatives 4.0 Internationalhttp://creativecommons.org/licenses/by-nc-nd/4.0/free radicalsEPRSaharan dustparticulate matterair pollutionraw dataset