Figure

Trend in NO2 and NOX annual mean concentrations (2001–2010) per station type (top); percentage frequency distribution of estimated annual change of NO2 annual mean concentrations at urban stations and at traffic stations (bottom)

Figure Created 26 Sep 2012 Published 26 Sep 2012 Last modified 29 Nov 2012

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All stations in EU Member States, with at least 75 % data coverage for at least eight years were included in the analysis. Concentrations per station type are given in μg/m3. In the top two diagrams a geographical bias exists towards central Europe where there is a higher density of stations. In the percentage frequency distribution graphs, closed bars denote stations showing a statistically significant trend, open bars denote stations with a non-significant trend. Statistically significant trends (level of significance 0.1) are calculated by applying the Mann-Kendall test. The applied method is described in de Leeuw, 2012.