Research data supporting “Insights into the sources of ultrafine particle numbers at six European urban sites obtained by investigating COVID–19 lockdowns"

Positive Matrix Factorisation (PMF) is a mathematical technique commonly used for source apportionment of air pollutants. Here, we applied PMF to particle size distribution (PSD) data from six monitoring sites across Europe to better understand how particle number concentrations and their sources (referred to as factors) changed during the respective 2020 lockdown periods compared to the reference years 2014–2019, depending on data coverage. The G matrix represents the factor contributions and the F matrix represents the factor profiles. “G_Matrices.csv” contains the G matrices from individual PMF runs for each site. “Factor” is the number assigned by PMF. “FactorName” is the manually assigned name to each factor for each site”. “Country” and “Type” collectively denote each site. “date” gives the time in local time for each site in YYYY-MM-DD HH:MM:SS format. “G_val” is the G Matrix values. “F_Matrices.csv” contains the F matrices from individual PMF runs for each site. “Factor” is the number assigned by PMF. “FactorName” is the manually assigned name to each factor for each site”. “Country” and “Type” collectively denote each site. “Diameter” refers to each mobility particle size spectrometer (MPSS) size bin. “dNdlogdp” is the F Matrix values.