Monitoring changes of PM2.5 and carbonaceous compositions during dry season in South Jakarta, Indonesia

¹ Department of Geosciences and Civil Engineering, Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa 920-1192, Ishikawa, Japan
² Faculty of Geosciences and Civil Engineering, Institute of Science and Engineering, Kanazawa University, Kanazawa 920-1192, Ishikawa, Japan
³ Department of Environmental Engineering, Faculty of Infrastructure Planning, Universitas Pertamina, Jakarta, Indonesia

^* Corresponding author: fatimahdinanq@gmail .com

Abstract

Air pollution in Jakarta, Indonesia, poses major environmental and health concerns due to persistently high fine particulate matter (PM_2.5) concentrations. This study investigated PM2.5 from May to September of 2023, covering early to late dry season, with a focus on carbonaceous components, including organic carbon (OC) and elemental carbon (EC), to assess monthly variability and understand emission influences. Daily PM_2.5 concentrations averaged 43.6 ± 9.4 μg/m³ (N = 153), exceeding the Indonesia NAAQS daily standard of 55 μg/m³ on 8.5% of days. Carbonaceous component were analyzed intermittently on 29 sampling days using the Thermal Optical Reflectance (TOR) Method. Total carbon (TC) accounted for 12-64% of PM2.5 mass, with OC consistently exceeding EC. Mean OC and EC concentrations were 10.1 and 3.9 μg/m³, respectively, and the OC/EC ratio remained relatively stable (mean = 2.6), indicating persistently OC-rich aerosols. PM2.5 increased from the early to the late dry season, whereas the TC fraction decreased, suggesting a greater contribution from non-carbonaceous components under prolonged dry conditions. These results highlight the important role of carbonaceous aerosols in Jakarta’s urban PM_2.5 pollution and the need for more detailed chemical speciation to improve source apportionment.