Mean and maximum values of annual averages of NO2 for traffic and urban background stations

Since the available data (stations) vary from year to year (see Tables 2 and 3) only the years 1999-2001 were chosen in order to ensure a consistent dataset across these years. Meteorological data are not available, so meteorologically induced changes cannot be analysed. The traffic stations were selected according to their yearly data availability and their completeness as regards hourly data availability. For certain years and stations the data availability was low, however these were used as no alternative was available. See Table 1 for details.