The characteristics of the concentrations and the seasonal variations of PM_(2.5),as well as the chemical compositions were analyzed from January 1 to December 31,2013. For this purpose,the online monitoring data at four air-quality monitoring sites and the chemical compositions of the sampled PM_(2.5)in Handan were used. The results showed the air quality standards for PM_(2.5)and PM10 were exceeded at different degrees during the four seasons. There was no significant difference in the PM_(2.5)concentrati...