HEALTH RISK ASSESSMENT OF INHALATION EXPOSURE TO PAHs ADSORBED ON PM2.5 AT RESIDENTIAL AREAS LOCATED IN THE INNER CITY OF BANGKOK

Abstract

This research studied on health risk assessment of the residents exposed to polycyclic aromatic hydrocarbons (PAHs) adsorbed on particles smaller than 2.5 &micro;m (PM2.5) via inhalation at the residential areas in the inner city of Bangkok. Particulate matters (PM2.5 and PM2.5-10) were collected on Sunday, Tuesday, and Friday for 24 hours in dry season (April to May 2013) and wet season (September to October 2013) at five representative communities in Pathumwan district. The air sampling was performed by using a personal modular impactor (PMI) connected to personal air pump with the flow rate of 3 L/min. PAHs adsorbed on particles were analyzed by HPLC with fluorescence and UV detectors. The indoor concentrations of PM2.5 and PM10 (PM2.5+PM2.5-10) ranged from 7.52 to 92.85 &micro;g/m3 and from 13.64 to 123.82 &micro;g/m3, respectively. Whereas, the outdoor concentrations of PM2.5 and PM10 ranged from 9.44 to 68.60 &micro;g/m3 and from 17.72 to 134.37 &micro;g/m3, respectively. The indoor and outdoor concentrations of total PAHs adsorbed on PM2.5 (t-PAHs2.5) ranged from 0.04 to 4.92 ng/m3 and from 0.09 to 4.22 ng/m3, respectively. The significant correlation between PM2.5 concentrations and the concentrations of t-PAHs2.5 could be obtained with the Pearson correlation (r) of 0.660 at 95% confidence (p<0.05). With respect to the results of diagnostic ratios, sources of both indoor and outdoor PAHs were from vehicle emission and fuel combustion. For lifetime cancer risk (LCR) of the residents at five communities, Benzo(a)Pyrene equivalent (BaPeq) was applied for the calculation. Regarding to LCR base on general scenario, the 95% confidence intervals of LCR exposure to total BaPeq in PM2.5 (t-BaPeq2.5) ranged from 1.29x10-6 to 2.99x10-6. In case of age interval scenario, the 95% confidence intervals of LCR exposure to t-BaPeq2.5 ranged from 3.69x10-6 to 11.57x10-6. The cancer risk from both scenarios were above the acceptable level (1x10-6).