Hourly Black Caebon usually concentrated in the range of 0.5– 2.0 mgm−3 in spring and autumn, and 0.0–1.0 mgm−3 in fall and winter. High hourly Black Carbon loadings exceeding the average (2.52 mgm−3) were about 46% in spring, 33%–38% in fall and winter, and 22% in summer. Throughout the sampling period, about 50% of Black Carbon events of hourly Black Carbon levels exceeding 7 mgm−3 within continuous 4 h appeared in spring. As back trajectories corresponding to days with high Black Carbon concentrations, air pollution outflows were popular in northerly, northwesterly, and southerly pathways in fall and spring, westerly in winter, and southerly in summer.