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In order to understand the concentration characteristics of PM(Particulate Matter) in sandstorm season,PM concentrations were observed in the spring of 2002.The observational results show that the concentrations of PM were lower in the periods without sandstorms than those with sandstorms.During sandstorms,the air quality became very poor.The results also show that there are significant linear correlation between PM10 and TSP,PM10 and PM2.5 concentrations.The added contribution of sandstorm weather to the vari-sized PM concentrations is about 33% to 86%.