Evaluation of organic carbon, elemental carbon, and water soluble organic carbon concentration in PM2.5 in the ambient air of Sina Hospital district, Tehran, Iran

Abstract

In the present study, carbon species including organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC) concentration in PM 2.5 were assessed at an urban site of Tehran, Iran during March to June 2014. The PM 2.5 samples were collected using an frmOMNI TM Ambient Air Sampler. Thermal gravimetric analysis (TGA) was used to analyze OC and EC. The results showed that PM 2.5 concentrations varied from 14.32 to 74.45 µg/m 3 with an average value of 41.39 µg/m 3 . The results also showed that carbon species varied from 5.52 to 23.21 (15.35 ± 6.05) µg/m 3 for OC and 1.03 to 4.16 (2.25 ± 0.65) µg/m 3 for EC. As the findings indicated, the mean PM 2.5 level in the sampling area was higher than the annual average determined by the United States Environmental Protection Agency (EPA) as the ambient air quality standard. On average, carbon species (OC, EC, and WSOC) account for almost 60% of PM 2.5 mass in the atmospheric outflow from a downwind site. OC and EC concentrations in atmospheric PM 2.5 collected at the sampling site were lower than the values reported for other urban areas with high or medium vehicular traffic and/or industrial sources. Moreover, the results obtained in this research can provide a valuable data base for health risk evaluation of the local residents and prioritization of control actions.