Abstract: ObjectiveTo assess air pollution levels and affecting factors of particulate matter less than 2.5 microns in aerodynamic diameter(PM2.5)at traffic crossroad during heating period and non-heating period in Taiyuan and to provide reference for the preventoin of PM2.5 pollution in traffic environment.MethodsKangle crossroad was selected as the monitoring site and continuous sampling was performed from October to November in 2010.The concentration of PM2.5 was determined by membrane weighting method.And the temperature,wind speed,atmospheric pressure and traffic vehicle flow were recorded at the site.Results In October and November,the daily average concentration of PM2.5 were 0.137 mg/m³ and 0.162mg/m³,respectively,which were both higher than air quality standard for PM2.5 of US Environmental Protection Agency(EPA)(issued in 2006).The unqualified rate of PM2.5 concentration in October and November were 100% and 96.7%,respectively.Concentration of PM2.5 in heating period was higher than that in non-heating period(P<0.01).There was no difference in PM2.5 concentration in the morning,midday and afternoon.Negative correlations were observed between concentration of PM2.5 and wind speed,temperature,and atmospheric pressure,and a positive correlation between PM2.5 and traffic vehicles flow was observed.ConclusionPM2.5 pollution at traffic crossroad is very serious in Taiyuan.The concentration is affected by wind speed,temperature,atmospheric pressure,and traffic vehicle flow.PM2.5 pollution should be concerned.