Air pollutant levels depend on emissions but can also be affected by the meteorological situation. We examined air pollutant trends (PM10, NO2, O3 and SO2) in Slovenia, where in the past the main issue were SO2 levels. Now, the population is still exposed to PM10 and ozone levels that are above the recommended levels. Our goal was to assess if the levels of air pollutants were decreasing from 2002 to 2017 due to emission ceilings or were more influenced by changes in the meteorological situation. We modelled the relationship between levels, meteorological parameters, and seasonality and then used the models with the best estimated generalisation to adjust levels for meteorology. Models showed a significant relationship between meteorological parameters and PM10, NO2, and O3 levels, but not SO2. We analysed trends of raw and adjusted levels and compared them. Trends of PM10 and SO2 were decreasing at all locations for raw and adjusted data. The largest decrease was observed in SO2 levels where the largest decrease in emissions occurred. Trends of NO2 were also significant and negative at most locations. Levels of O3 did not exhibit a significant trend at most locations. Results show that changes in the meteorological situation affected PM10 levels the most, especially where the entire period (2002-2017) could be observed. There is strong empirical evidence that changes in meteorological parameters contributed to the decrease in PM10 levels while the decrease in NO2 and SO2 levels can be attributed to emission ceilings.
Keywords: Adjustment; Air pollutant levels; Emissions; Meteorology; Statistical models; Trend.
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