PM_2.5 mass concentrations observed at Fukue Island, Kyushu, Japan: Exceeding the atmospheric environmental standard

Abstract

We continuously monitored the PM_2.5 mass concentrations at Fukue Island located in the western part of Kyushu, Japan, and analyzed one year of data since 9 September 2009, when an environmental standard was newly introduced. The observed annual average, 17.3 μg m^-3, was not readily concluded to exceed the long-term standard value (15 μg m^-3) when the uncertainty of the zero level was taken into account. On the other hand, the 98 percentile of the daily average values during the year was 56.5 μg m^-3, clearly exceeding the short-term standard value (35 μg m^-3). The backward trajectory analysis suggested that the influence from the Asian continent was strong for the high PM_2.5 days. The high PM_2.5 days were found irrespective of the detection of dust at the Nagasaki meteorological station. The influence of air pollution is implied from the association of high black carbon concentrations with the elevated PM_2.5 events.