Changes in Concentration Levels of Polycyclic Aromatic Compounds Associated with Airborne Particulate Matter in Downtown Tokyo after Introducing Government Diesel Vehicle Controls

• Published in: Asian journal of atmospheric environment (Online) Vol. 4; no. 1; pp. 1 - 8
• Main Authors: Kojima, Yuki, Inazu, Koji, Hisamatsu, Yoshiharu, Okochi, Hiroshi, Baba, Toshihide, Nagoya, Toshio
• Format: Journal Article
• Language: Korean
• Published: 2010
• Subjects: Airborne particulate matter; Elemental carbon; PAHs; Nitro-PAHs; Diesel vehicle
• ISSN: 1976-6912; 2287-1160

The effectiveness of the government regulation on tail-pipe emission for diesel vehicles issued in 2003 in Tokyo was evaluated in this study. Variations in annual average concentrations of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs associated with airborne particulate matter were investigated in connection with the variation in airborne elemental carbon (EC) concentration in downtown Tokyo, Japan in 2006-2007 and in 1997-1998. The annual average concentrations of EC, seven different PAHs, and 1-nitropyrene were found to have decreased significantly from 1997-1998 to 2006-2007. The most prominent decrease in atmospheric concentration was observed for 1-nitropyrene, which is a representative nitro-PAH originating from diesel vehicles. This indicated that the government control has worked to considerably reduce both atmospheric mutagens and airborne particulate matter. In contrast, the concentrations of two nitro-PAHs, 2-nitrofluoranthene and 2-nitropyrene, remained the same. These nitro-PAHs are known to be formed by atmospheric nitration of their parent PAHs, and this result suggested factors other than the concentration of parent PAHs and $NO_2$ affects the degree of atmospheric formation of nitro-PAHs.