Local versus Regional Contributions to PM10 Levels in the Western Mediterranean

In this study, PM10 daily samples were collected every day during approximately one month in winter and one month in summer, 2019. Sampling was performed simultaneously at two different locations: an urban traffic site (~80 m a.s.l.) and a regional background station (~1500 m a.s.l.) in the western Mediterranean. The objective of this work was to investigate PM10 sources at both sites in order to determine regional and urban contributions to aerosol levels. Seven factors were obtained at both sites using Positive Matrix Factorisation (PMF): Saharan dust, Aged sea salt, Ammonium sulphate, Nitrate, Road traffic, Local dust and Fresh sea salt. At the urban site, the contribution of vehicle related sources (Road traffic, Nitrate and Local dust) was significantly higher in winter (~80%) than in summer (~60%). The average contribution of Saharan dust to PM10 levels was much larger at the mountain site (33%) than at the urban location (9%), due to the absence of significant anthropogenic emission sources in the vicinity of the regional background sampling station.