Carbonaceous components are important components of fine atmospheric particulate matter (PM_2.5) and can affect the local environment, climate, and human health. In this study, the daily atmospheric PM2.5 and carbonaceous aerosol (organic carbon (OC) and elemental carbon (EC)) concentrations were measured at Arconville in Abomey Calavi and Mahoule in Cotonou, Benin, Southwest Africa, from December 2016 to March 2017. The mass concentration and ratios of PM2.5 aerosol and organic and elemental carbon and the OC/EC radio were evaluated together to obtain better insight into their possible local and regional sources. For the studied period, the mean mass concentrations of PM2.5 aerosol were 64 ±16 µ.gm⁻³ and 79 ±18 µ.gm⁻³ at the traffic sites in Arconville and Mahoule, respectively. The OC and EC concentrations were 31 ± 13 μg·m⁻³ and 9 ± 06 μg·m⁻³ for Arconville's traffic and 38 ± 16 μg·m⁻³ and 13 ± 08 μg·m⁻³ at Mahoule, respectively. Adding together the total carbon (TC), it accounted for 62.5% and 64.56% of the PM2.5 at Arconville and Mahoule. The OC/EC ratio was 3.44 at Arconville and 2.92 at Mahoule, exceeding 2.0, which confirmed the presence of secondary organic aerosols during the long dry period at these two traffic sites.