Trend analysis of annual mean value time series of NO2, PM10 and ozone for the period of 1995 to 2007 depending on the monitoring network homogeneity

For evaluating reliable trends that are needed for air pollution control policy data originating from continuously measuring stations are required. Due to the temporal and spatial inhomogeneity of the German air quality monitoring network (closing and commissioning of measuring stations, their unbalanced distribution) trend evaluation based on spatial annual mean values may become doubtful. This work is aimed at comparing mean German nitrogen dioxide, PM10 and ozone concentrations within the pollution regimes "urban-near traffic", "urban background" and "rural background" of all available and continuously measuring stations. As a result of this comparison mean "urban-near traffic" time series should exclusively be assessed by using data from continuously measuring stations. Considering the air quality within the category "urban-near traffic" NO2 showed no significant trend. PM10 showed a significantly falling trend, ozone a significantly rising trend. Within "urban background" environment mean PM10 and NO2 concentrations decreased significantly, mean ozone concentrations increased. "Rural background" measurements show a falling NO2 trend, PM10 and ozone concentrations show no trend at all.