Note: The graph is based on annual mean concentration values. For each country, the lowest, highest and median values (in µg/m3) at the stations are given. The rectangles give the 25 and 75 percentiles. At 25% of the stations, levels are below the lower percentile; at 25% of the stations, concentrations are above the upper percentile. The target value set by EU legislation is marked by the red line. The WHO AQG is marked by the green line.
