Contribution of natural and anthropogenic radionuclides from saharan dust during the March 2022 event in the Iberian Peninsula

African dust outbreaks are recurrent events that have been extensively studied in the scientific literature. However, the intense event that occurred in March 2022 over Spain provided an opportunity to study various radiological aspects in depth due to the significant amount of suspended dust emitted and transported. The particles were morphologically and chemically characterised using SEM and EDX techniques. The chemical composition was homogeneous, with an Al/Fe ratio ranging from 0.48 to 0.72, consistent with that of the Sahara region. This study evaluates the radiological risk associated with ¹³⁷Cs and ²¹⁰Pb, determined from the activity concentrations of the dust, which were obtained through gamma spectrometry. The radionuclides from the uranium series (²¹⁴Pb) had an average value of 20.0 Bq kg^-1, while those from the thorium series (²²⁸Ac, ²¹²Pb, and ²⁰⁸Tl) averaged 35.2 Bq kg^-1. Additionally, the mean activity concentrations of ¹³⁷Cs were 11.0 Bq kg^-1, corresponding to fallout. The ratios of ¹³⁷Cs/⁴⁰K and ⁷Be/²¹⁰Pb, with medians of 0.023 and 2.2 respectively, indicated that the event influenced the lower layers of the atmosphere. Furthermore, the ratios obtained between ²¹⁰Pb/²¹⁰Po, determined using Bateman equations, confirmed a short residence time for ²¹⁰Pb. On the other hand, the results from the extraction of the exchangeable fraction of dust particles showed a strong association of ²¹⁰Pb and ¹³⁷Cs with the dust particles. Finally, the effective inhalation doses obtained were several orders of magnitude below the 3 μSv day^-1 limit recommended by the ICRP.