Analysis of Yinchuan air quality change trend from 2000 to 2009

The statistical analysis results of air quality monitoring data of Yinchuan City in 2000—2009 showed that the days of 2 or more pollutants level of three major items,SO2,NO2,PM10,were 100%,92%,83.3% to total polluted days respectively.The first important pollutants which influence Yinchuan air quality is PM10 and SO2,the days of 2 or more pollutants level were 68.1%,31.9% in total polluted days,and the days of 3 or more pollutants level were 57.1 and 26.7 in every year.Downtrend of all concentration of three kinds pollutant every year indicates the effectiveness of air quality improvement in Yinchuan City in recent years,the daily variation rules of main pollutants are consistent with enterprise producing,citizen traveling and turbulent changing time.Pollutants concentration of SO2 and NO2 are the highest in winter,the lowest in summer.PM10 is the highest in winter,middle in spring,and the lowest in summer.Pollution factors is relevant to coal-burning pollution and temperature inversion form heating with boiler and coal stove in winter for half year in northern city Yinchuan,and sandstorm and dust weather in spring and autumn.