Changes in PM10 concentrations, composition, and source contributions in the last decades in urban and regional Barcelona

PM 10 concentrations in Europe have been declining in the last decades. An analysis of the PM 10 concentrations and speciation measured at an urban and a regional background sites in NE Spain (BCN and MSY, respectively) is carried out with data from studies since 1999. Since 1999, the average PM 10 concentrations in BCN went from 49 to 20 μg m −3 (−1.4 [−2.3, −0.29] μg m −3 y −1 , p < 0.05). Having met the EU PM 10 standards in 2010, mild actions were implemented to abate PM 10 , with local and regional efforts focusing on NO 2 . In 2020–2021, PM 10 was composed by 25 % of mineral matter (MM, 11 % desert dust +14 % urban dust), 22 % organic matter, 20 % secondary inorganic aerosols (SIA), 3 % elemental carbon, and 8 % sea salt (SS). Moreover, 19 % of PM 10 has a natural origin, being a relevant contribution for compliance of the PM 10 limit value (20 μg m −3 ) of the Air Quality Directive (EU) 2024/2881. Receptor modelling for 2020–2021 identified 10 major sources contributing to PM 10 : aged sea salt, mineral and vehicle emissions accounted for 81 % of the PM 10 . This study is the first in Barcelona not being able to identify a shipping profile. Despite substantial reduction of direct shipping emissions, moored cruise ships are identified as its primary PM 10 contributor. Overall, the results provide relevant information on the impact of policy actions implemented, and on identifying major target sources for the abatement of PM in urban environments of the W-Mediterranean. • Barcelona PM 10 was cut by over half between 1999 and 2021. • 2020–21 PM 10 hit historic lows in Barcelona due to COVID-19 lockdown restrictions. • Vanadium in PM 10 fell sharply in 2020–2021, linked to cruise shipping restrictions. • Mineral and organic matter dominated Barcelona's PM 10 in 2020–2021. • Largest reductions were observed for secondary inorganic aerosols.