Particles size distribution of PM 11 and its impact on visibility in urban Shijiazhuang during spring

Atmosphere particles collected by Andson AN-200, were divided into PM 0.43 , PM 0.43∼0.65 , PM 0.65∼1.1 , PM 1.1∼2.1 , PM 1.1∼2.1 , PM 2.1∼3.3 and PM 3.3∼4.7 , PM 4.7∼7 and PM 7∼11 , in total eight ranks. After calculating the particles mass concentration of all ranks and studying the correlation coefficient between particles mass concentration and visibility, we conclude: The finer particles pollution is the main reason for the atmosphere particles pollution in spring of Shijiazhuang, The particles mass concentration of PM 0.43 is the highest(0.040 mg/m 3 ). The proportion of PM 2.1 in PM 11 is 53.7%. The air pollution particularly finer particles of pollutes is the most serious. The correlation coefficient between particles mass concentration and visibility is r 0.43∼0.65 > r 0.65∼1.1 > r 0.43 > r 1.1∼2.1 . The correlation coefficient between other particles mass concentration and visibility is not significant at the 0.01 level (2-tailed). The finer particles are the main factors that lead to low visibility. The correlation coefficient is −0.684 between visibility and relative humidity in urban Shijiazhuang during spring. The correlation coefficient is 0.395 between visibility and wind.