Annually in the springtime,air quality in the Kyushu area (southwestern Japan) frequently deteriorates with increased PM concentrations.We performed a sampling campaign in Kumamoto City through a period from 17th March to 28th April in 2011,in which the 24-hour PM filter samples were collected with a high-volume air sampler (1000 liter/min) equipped with particle size selector of 10 μm cut-off size.