Characteristics of gas- and particle-phase polycyclic aromatic hydrocarbon (PAH) distribution in tunnels

Abstract

Twenty four individual polycyclic aromatic hydrocarbon (PAH) compounds both in gas- and particle-phase were quantified in three tunnels (Namsan Tunnel 3, Jeongneung Tunnel, Bukak Tunnel) to characterize vehiculate emission of PAHs. Gas phase PAHs were dominant in tunnels which consisted of 85% of total PAHs concentrations. Naphthalene and 2-methyl naphthalene were the most abundant gas phase PAH compounds, while the concentrations of fluoranthene and pyrene were highest in the particle phase. Most (96%) of the gas phase PAH compounds consisted of two- and three-aromatic rings whereas most of the particle phase PAHs were in four and five-rings (67%) in tunnels. Average BaP-eq concentrations of PAHs in the particle phase (20.8±11.6 ng m-3) was about twenty fold higher than that in the gas phase (1.6±0.6 ng m-3). It means that the particle phase PAHs has more adverse health effect than the gas phase PAHs even though the concentrations of the particle phase PAHs were lower than those of the gas phase PAHs. Compared to previous studies reporting diagnostic ratios for specific PAH compounds, the profile of individual PAH compounds measured in this study reflected well for the vehiculate emissions. We reported, for the first time, on the results of the profile of individual PAH compounds measured in tunnels for both gas and particle phases.