Abstract
Airborne particulates were collected in Noge and Kudan, Japan, in the summer and winter from 2006 to 2013 and in Tsukuba, Japan, in the summer and winter from 2010 to 2013. The polycyclic aromatic hydrocarbons (PAHs) and nitropolycyclic aromatic hydrocarbons (NPAHs) were determined by HPLC with fluorescence and chemiluminescence detections, respectively. The decreasing tendencies of the total concentrations of nine PAHs were observed at Noge and Kudan in the winter from 2006 to 2008. The decreasing tendencies of the total concentrations of three NPAHs were observed in both the summer and winter in Noge from 2006 to 2011. The decreasing tendencies of the NPAH concentrations were also observed in Kudan in the winter from 2006 to 2011 and in the summer from 2007 to 2009. The concentration ratio of 1-nitropyrene to pyrene also decreased in Noge and Kudan. As the main reason for the decrease in the urban atmospheric PAH and NPAH concentrations, the Japanese regulation of exhaust gas/particulates from automobiles was considered.
