Analysis on the chemical and physical properties of particles in a dust storm in spring in Beijing

In spring 2000, dust weather occurred frequently in Beijing, which had a detrimental effect on the quality of atmospheric environment. The dust storm that occurred on April 6, 2000 is the severest one in 2000 in Beijing. The chemical composition and number concentration of this dust event were observed in time. The total mass concentration of dust on April 6 reached 3906.2 μg/m3, which is 36 times that of non-dust weather days and 8 times that of another dust weather on April 25, 2000. The mass concentration of particles with diameter less than 2 μm on April 6 reached 275.8 μg/m3, which greatly exceeds EPAʹs 24-h PM2.5 standard. The period of this high concentration lasted at least 9 h. Observations by optical particle counter show that the dust storm caused a considerable increase of number concentration of particles of d>0.5 μm and had little influence on number concentration of particles of 0.3<d<0.5 μm.