2011 Volume 46 Issue 2 Pages 111-118
The concentrations of PM2.5 at Fukuoka City (population of 1,440,000) and at Fukue Island (population of 40,000, 190 km west of Fukuoka City) in Kyushu, the western part of Japan, were compared during the Japanese fiscal year 2009. The similarity in the concentration and temporal variations of the hourly PM2.5 at Fukue and Fukuoka seen in April, 2009, described in a previous paper, was also observed in the summer, fall, and winter. PM2.5 monitoring in Nagasaki City, started in October, 2009, also showed a behavior almost identical to the other two sites. These temporal variations are the result of long-range transport mechanisms driven by synoptic weather systems such as “behind the front” and “circular flow around migrating anticyclones.” In addition, in the rainy season during July, the Meiyu/Baiu stationary front plays a critical role in the occurrence of high concentration events as being the southern border of the continental air mass. As a result, the monthly average PM2.5 concentrations at these three sites were almost the same throughout the year. The results of the FY2009 monitoring suggest that in the northern Kyushu area, even in a city as large as Fukuoka, the concentration of PM2.5 was dominated by the long-range transport of air pollution rather than domestic urban air pollution throughout the year.
