Airborne particulates have been continuously collected at four cities in Japan starting in the late 1990s, at major cities in China, Korea and Russia starting in 2001 and at Noto peninsula starting in 2004. After extracting and cleaning up particulates, nine polycyclic aromatic hydrocarbons (PAHs) and eleven nitropolycyclic aromatic hydrocarbons (NPAHs) were determined by HPLC with fluorescence and chemiluminescence detections, respectively. Annual concentrations of PAHs and NPAHs at the cities were in the order, China &gt
Russia &gt
Korea &gt
Japan. Concentrations of PAHs and NPAHs in Japanese cities significantly decreased but different tendencies were observed in Chinese and Russian cities. On the Noto peninsula, which is in the main path of winter northwest winds and a year-round jet stream that blow from the Asian continent to Japan, the concentrations of PAHs and NPAHs were high in winter and low in summer every year. A cluster analysis and back trajectory analysis indicated that PAHs and NPAHs at the Noto peninsula in winter mainly came from coal burning systems in Northeast China.