ETC/ATNI Report 2021/9: Long-term trends of air pollutants at national level 2005-2019

Trend calculations of air pollutants for the periods 2005-2019 have been applied. Sulphur dioxide shows the largest decrease of all pollutants with a reduction of the order of 60-70 %. The agreement between reported emission data and measured concentrations are quite good. For NO2, a mismatch between the trend in air concentrations and NOx emissions is found. While the overall NOx emissions are reported to be reduced by 45 %, the measured NO2 data indicate a decline of the order of 30 %. For PM data (PM10 and PM2.5) we find an opposite mismatch, meaning that the PM concentrations show stronger downward trends than the reported emissions. This can be explained by the additional effect of reducing gaseous precursors of secondary PM. For O3, our findings are in line with earlier published studies noting that the annual mean ozone concentration has increased while the high peaks have been reduced. But the reduction of the peaks is now within only a few percent and non-significant.