Measurements of sulfate particles using a commercial sulfate monitor were performed in Imizu City, Toyama Prefecture in the summer of 2009 and at Bijodaira (altitude, 977 m) on the western slope of Mt. Tateyama in the autumn of 2008 and 2010. Concentrations of sulfate had a good correlation with those of PM2.5 in Imizu City. The highest concentrations of PM2.5 and sulfate during the observation period were measured during 27-29 June, 2009. The diurnal variations of PM2.5 and sulfate were unclear in Imizu City. The temporal variations of sulfate were similar to those of the number concentrations of the fine particles at Bijodaira, however, the diurnal variations of sulfate were different from those of the number concentrations. High concentrations of sulfate and the number concentrations of particles associated with the increase of O3 and SO2 were often observed. The high concentrations of sulfate may be due to the long-range transport of air pollutants from the Asian continent.
