Figure 3 also displays the normalized frequency patterns of hourly Black Carbon measured during the whole campaign. As seen in Figure 3, hourly Black Carbon concentrations were almost below 10 mgm−3, and more than 85% of hourly Black Carbon was less than 6 mgm−3 in all seasons. High hourly Black Carbon loadings exceeding the average (2.52 mgm−3) were about 46%, 22%, 38%, and 33% in spring, summer, fall, and winter, respectively, implying that summer was a clear period with low Black Carbon levels.