The spatiotemporal variability of PM2.5 carbonaceous aerosol species was investigated during June and December 2022 at three different sites: Industrial, Commercial, and Urban Roadside in the semi-arid region of Rajasthan. In summer, average PM2.5 concentrations were 64.7 ± 15.2 μg/m³, 62.4 ± 15.5 μg/m³, and 64.6 ± 17.2 μg/m³ at industrial, commercial, and urban roadside sites, respectively. In winter, average PM2.5 concentrations were 154.2 ± 29.5 μg/m³, 132.6 ± 35.6 μg/m³, and 119.7 ± 42.4 μg/m³ at industrial, commercial, and urban roadside sites, respectively. The concentrations of OC, EC, and the OC/EC ratio varied between the different sampling sites and seasons. In summer, the average OC/EC ratios were 6.3 ± 1.3, 7.7 ± 2.1, and 4.2 ± 0.9 at the industrial site, commercial site, and urban roadside, respectively, while in winter the average OC/EC ratios were 4.6 ± 0.51, 4.61 ± 0.56, and 3.1 ± 0.51 at the industrial site, commercial site, and urban roadside, respectively. Furthermore, secondary organic carbon (SOC) was estimated by selecting the minimum [OC/EC] value from the entire dataset and by regression analysis of [OC/EC] in lower data segments (~5% - 25%). The results highlight the potential implications for human health and climate.