Twelve-Year Trends of PM₁₀ and Visibility in the Hefei Metropolitan Area of China

Figure 6

Annual region-average percentages (%) of visibility lower than 5 km (left -axis) and higher than 10 km (right -axis) in Hefei during 2001–2012. Black dashed lines and blue dotted lines are the linear regression curves of the corresponding trend lines, splitted by year 2006 (the red short dashed line).