Modelling long-term averages of local ambient air pollution in Oslo, Norway: evaluation of nitrogen dioxide, PM10 and PM2.5

Large seasonal variations in climate as in Norway give challenges for air pollution modelling, especially of Particulate Matter (PM) that seldom has been evaluated. The EPISODE model calculated ambient concentrations of nitrogen dioxide (NO2), PM with diameter <10 mu m (PM10) and <2.5 mu m (PM2.5), for geographical coordinates in Oslo, Norway, for the period 1992-2002. This paper describes EPISODE and the emission database used, and compares long-term model estimation of local ambient air pollution with available measurements from monitoring stations in Oslo during one winter season (1996/1997) and one year (2001/2002). We find good agreement between measured and modelled concentrations except for summertime PM10. Bias and scatter are lower at the urban background stations compared to the traffic stations. These results indicate that the EPISODE model can represent long-term concentrations of local ambient NO2, PM10 and PM2.5, suggesting future use of the model in epidemiological studies.