The red line corresponds to the EU limit value of 125 μg/m3, EU Member States only.
The graph is based on the 99.18 percentiles of the daily mean concentration values for each Member State; the boxes
present the range of the 99.18 percentiles at all stations types (in μg/m3) with data officially reported by the EU Member
States and how they relate to the daily limit value set by EU legislation (marked by the red line).
The diagram indicates the lowest and highest observations, the means and the lower and upper quartiles. The lower quartile
splits the lowest 25 % of the data and the upper quartile splits the highest 25 % of the data.

References and footnotes