Chemical characterization of PM2.5 (major and trace elements) was carried out for a source apportionment study of PM2.5 at a traffic site in Constantine, Algeria, from March 2017 to March 2018. For this purpose, several tools were used of which PMF, CPF, PSCF, Spearman correlation matrix and HYSPLIT back trajectories. The mean annual concentration of PM2.5 at the sampling site was 54.07 ± 28.81 µg/m3. This value is much higher than the annual threshold recommended by the WHO of 10 μg/m3. Based on the PMF modelling, five sources were identified: sea salts (15.1%), industrial activities (18.9%), non-exhaust emissions (wear of brakes, tires and road surfaces) (24.2%), exhaust emissions (mixed diesel and gasoline engine exhaust) (15.8%) and mineral dust (25.9%) as the main sources of metallic aerosols at the sampling site in Constantine. Our results revealed that anthropogenic activities (traffic and industry) contributed 59% to all emissions, while natural sources (mineral dust and sea salt) accounted for 41%. Traffic-related sources are the major contributor to anthropogenic emissions (40%) with non-exhaust emissions being the dominant source. As anthropogenic emissions are the leading sources, their control is of utmost importance for improving air quality. The concentrations of PM2.5 tend to increase appreciably with temperature and wind speed for a relative humidity less than 60%. The contribution of vehicular emissions is affected by relative humidity and temperature while industrial emissions are affected mainly by wind intensity and direction. Relative humidity, temperature and wind speed are determining parameters of mineral dust. There are seasonal variations in the contributions of the PMF-derived sources. Summer undergoes significant contributions of three factors: sea salts, industrial emissions and mineral dust. Spring is affected mainly by industrial emissions and non-exhaust emissions. Winter experiences a drastic contribution of the exhaust emission factor. Autumn is the least affected season by mineral dust and sea salts. It is rather affected by industrial and traffic emissions.