Comparison of atmospheric polycyclic aromatic hydrocarbon levels in three urban areas in Lebanon

Introduction: Reports on the levels and sources of PAHs in the Middle Eastern region are very scarce and mostly outdated. This study reports for the first time the ambient levels of PAHs during summer and winter at three coastal locations in Lebanon. Comparison between PAH levels in the three locations is established and the contribution of major emission sources to PAHs is evaluated. Materials and methods: Gas and particle phase PAHs were collected using a high-volume sampler fitted with a quartz filter and a polyurethane foam (PUF) holder at three coastal sites (American University of Beirut, Dora, and Zouk Milcael). The collected PAHs were then extracted and analyzed by gas chromatography-mass spectrometry (GC-MS). The dispersion of pollutants in the emissions from a local power plant was evaluated using The Air Pollution Model (TAPM), coupled with field measurements to quantify the BaP level in two nearby locations and one background location. One-way ANOVA tests and coefficients of divergence (COD) between paired sites were used for data analysis. Results: High heterogeneity was detected in the temporal and spatial variations of the PAH profiles and concentrations at the three coastal urban sites. Higher PAH levels were measured in winter than in summer at AUB and Dora, but not at Zouk Mikael. Major sources of pollution were identified as traffic, diesel engines, road dust, and oil fuel. Diesel engines are used as local sources of electricity during rotating blackout and oil fuel are used to run the inadequately maintained local power plant. The BaP levels measured near the power plant were approximately 10 times higher than those at the background site. Conclusions: The annual average BaP concentrations of 2.07 ng m(-3) and 2.9 ng m(-3) at Zouk Mikael and Dora, respectively, exceeded the European Union (EU) air quality standard of 1 ng m(-3). Owing to the lax governmental regulations, the BaP levels in Lebanon are higher by 60%-99% than those in most cities around the world.