6.3 Concentration maps for selected cities in 2019 and 2030
Concentration maps for the selected cities in each of the Nordic countries for 2019 and 2030 are presented in the following for annual means of NO2, O3 and PM2.5. The dashed lines displayed in the maps are a rough indication of the extent of the city boundaries as applied in this analysis. Missing maps reflect data limitations as described previously.
General assessment
The geographic distribution of concentrations in the cities is seen to be influenced by population density and thereby associated emission density as well as large road transport corridors and ship traffic. Concentrations of NO2 and PM2.5 are decreasing for all cities from 2019 to 2030, whereas concentrations of O3 are slightly increasing.
Urban background NO2 and PM2.5 and WHO AQG
The UBM model generally overestimates NO2 concentrations and caution should be taken when comparing modelled concentrations with WHO AQG. Therefore, an estimate of compliance with the WHO AQG in 2030 also considers the present observed concentrations in 2019. In the following focus is on the capital cities that generally have the highest concentrations levels.
Based on the observed level of NO2 in 2019 at the urban background station in København (11.9 µg/m3, 9.8 µg/m3 in 2021) and the modelled decrease in concentrations towards 2030 of 19%, it is likely that concentrations will be under the WHO AQG of 10 µg/m3 in 2030 at this station. The average modelled concentration over the mask of København of 17 µg/m3 in 2030 seems overestimated.
Based on the observed level of NO2 in 2019 at the urban background station in Stockholm (10.4 µg/m3, 11.0 µg/m3 in 2021) and the modelled decrease in concentrations towards 2030 of 26%, it is likely that concentrations will be under the WHO AQG of 10 µg/m3 in 2030 at this station. The average modelled concentration over the mask of Stockholm of 24 µg/m3 in 2030 seems overestimated.
Based on the observed level of NO2 in 2019 at the urban background station in Helsinki (14.9 µg/m3, 12.4 µg/m3 in 2021) and the modelled decrease in concentrations towards 2030 of 21%, it is likely that concentrations will be slightly under the WHO AQG of 10 µg/m3 in 2030 at this station. The average modelled concentration over the mask of Helsinki of 19 µg/m3 in 2030 seems too high.
Based on the observed level of NO2 in 2019 at the urban background station in Reykjavík (9.3 µg/m3, 8.2 µg/m3 in 2021) and the modelled decrease in concentrations towards 2030 of 13%, it is likely that concentrations will remain under the WHO AQG of 10 µg/m3 in 2030 at this station. The average modelled concentration over the mask of Reykjavík is 9 µg/m3 in 2030.
The comparison of observed and modelled concentrations to PM2.5 showed some overestimation for the lowest observed values and some underestimation of the highest observed values. Based on the observed level of PM2.5 in 2019 at the urban background station in København (10.9 µg/m3, 8 µg/m3 in 2021) and the modelled decrease in concentrations towards 2030 of 20%, it is likely that concentrations will be slightly over the WHO AQG of 5 µg/m3 in 2030 at this station. The average modelled concentration over the mask of København is 7 µg/m3 in 2030.
Based on the observed level of PM2.5 in 2019 at the urban background station in Stockholm (4.9 µg/m3, 5.1 µg/m3 in 2021) and the modelled decrease in concentrations towards 2030 of 13%, it is likely that concentrations will be under the WHO AQG of 5 µg/m3 in 2030 at this station. The average modelled concentration over the mask of Stockholm is 7 µg/m3 in 2030 seems to be overestimated.
Based on the observed level of PM2.5 in 2019 at the urban background station in Helsinki (5.6 µg/m3, 5.8 µg/m3 in 2021) and the modelled decrease in concentrations towards 2030 of 15%, it is likely that concentrations will be under the WHO AQG of 5 µg/m3 in 2030 at this station. The average modelled concentration over the mask of Helsinki is 7 µg/m3 in 2030.
Based on the observed level of PM2.5 in 2019 at the urban background station in Reykjavik (7.9 µg/m3, 4.9 µg/m3 in 2021) and the modelled decrease in concentrations towards 2030 of 27%, it is likely that concentrations will be under the WHO AQG of 5 µg/m3 in 2030 at this station. The average modelled concentration over the mask of Reykjavík is 2.3 µg/m3 in 2030.
Due to data limitations no modelled concentrations for 2030 are available for Oslo.