Both episodes were characterized by the long-range transport of dust at 15 m over Warsaw and the concentrations of the soil component being 7 (up to 3.5 µg m −3) and 6 (up to 6.1 µg m −3) times higher than the mean concentrations observed during non-episodes days (0.5 and 1.1 µg m −3) in the fine and coarse fractions, respectively. In addition, two intensive Saharan dust outbreaks were registered on 18 February and 8 March 2016. Regional transport of aged aerosols and more local impact of the rest of the identified sources played a crucial role in aerosol formation over the city.

In the fine fraction, aged sulfate aerosol related to emissions from domestic solid fuel combustion in the outskirts of the city was the largest contributing source to fine elemental mass (44 %), while traffic-related sources, including soil dust mixed with road dust, road dust, and traffic emissions, had the biggest contribution to the coarse elemental mass (together accounting for 83 %). Another two sources, i.e., Cl-rich and wood and coal combustion, were solely identified in the fine fraction. Identification of five similar sources in both fractions, including sulfates, soil dust, road salt, and traffic- and industry-related sources. Receptor models was applied for source apportionment. (Conditional Probability Function) and trajectory-based (Cluster Analysis) AĬombination of multivariate (Positive Matrix Factorization) and wind. Period at a Central European urban background site in Warsaw, Poland. (PM 2.5−10) fraction of atmospheric particulate matter was measured at an hourly time resolution by the use of a streaker sampler during a winter The elemental composition of the fine (PM 2.5) and coarse

Industry 4.0 elements