The Danish urban air quality monitoring program: Objectives and results

Air quality in Danish cities has been monitored since 1982 within the LMP network. The main objectives have been to provide a comprehensive description of the levels of inorganic pollutants, especially in relation to limit and guide values, and to assess the source contributions. The main source types are traffic, other local anthropogenic pollution (mainly from domestic heating) and long range transported pollution. At the present stage eight stations in three cities are in operation focusing on the difference between street level and urban background pollution with special emphasis on the NOx-O-3 relationship. SO2 and Pb pollution has been steadily decreasing and the concentrations are at present below the EU limit and guide values. The NO, level has however been almost constant and is, at the most polluted localities, close to the EU guide values. The dispersion of NOx from urban traffic and the importance of O-3 for the formation of NO2 is described on a phenomenological basis.