# A Comparative Study of SOx, NOx, PM2.5 and PM10 in the UK and Poland from 1970 to 2020
## 5 Comparison between Air Pollution in the UK and Poland  
Figure 9 shows a comparison of the evolution of various air pollutants between 1990 and 2020. It is evident that, during this period, the level of air pollution decreased in both countries, albeit at different rates. Additionally, noteworthy observations include the significantly higher levels of PM2.5 and PM10 in Poland compared to the UK, while the level of NOx was higher in the UK. Up until 1996, the level of SO2 was higher in the UK, but between 1996 and 2020, the level of SOx in Poland surpassed that of the UK. Figure 8: Schematic showing evolution of regulations over the years. Further information on the Directives and Protocols can be found in the references [33; 34; 35; 36]. Figure 9: Comparison of the level of emissions of NOx (**a**), PM2.5 (**b**), SOx (**c**), and PM10 (**d**) in the UK and Poland. The higher levels of SO\({}_{2}\), PM10, and PM2.5 observed in Poland can be attributed to the heavy reliance on coal for energy, as opposed to the UK's gradual transition to alternative energy sources. This distinction is clearly shown in Figure 10, depicting the changing share of energy consumption in both countries from 1960 to 2020. The data reveal that the combustion of coal and oil has been the primary source of energy in Poland, leading to elevated levels of SO\({}_{2}\) and PM emissions. Conversely, the UK has been actively reducing coal usage and increasing reliance on natural gas, known for emitting extremely low levels of SO\({}_{2}\) and negligible amounts of PM. It should be noted that natural events, such as volcano eruptions or natural dust blown, for example, from deserts, can also influence the level of air pollution. In 2010, the eruption of Eyjafallajokull volcano took place in Iceland. During the eruption, high levels of gases, such as SO\({}_{2}\) and CO\({}_{2}\), were released into the atmosphere together with volcanic ashes. It can be noted from Figure 9 that the volcanic event in 2010 did not have a huge influence on the SOx level neither in the UK or Poland. However, it can be noted that the level of PM10 and PM2.5 was elevated in 2010 in both countries. The higher level of NOx in the UK can be attributed to the higher level of traffic in the country. Figure 11 shows the number of new cars registered in the UK and Poland between 2003 and 2021. More cars were registered in the UK, which indicates a higher likely level of traffic. Since the main source of NOx emission is hydrocarbon-based transportation (Figure 2), the higher concentration of NOx in the UK is not surprising. The overall air pollution levels in Poland remain significantly higher than those in the UK, with unfortunate consequences reflected in the number of air pollution-related deaths. Figure 12 illustrates air pollution-related deaths as a percentage of global disease deaths from 1990 to 2019, indicating consistently higher levels of air pollution-related mortality in Poland compared to the UK during this period [21; 22]. In 2019, only 2.4% of disease deaths were attributed to air pollution in the UK, whereas in Poland, this figure was notably higher, at 7.4%. Figure 10: Comparison of share of energy consumption (by source) in Poland and the UK. Curiosity may arise about how the air quality situation in Poland and the UK compares to that in other European countries. Figure 13 depicts the level of PM2.5 pollution across various European nations. Notably, in 2021, Poland ranked as the seventh most polluted country in Europe, surpassing WHO guidelines for PM2.5 (5 \(\upmu\)g/m\({}^{3}\)) by 3 to 5 times [23]. In contrast, the UK's PM2.5 levels exceeded the guidelines only by 1 to 2 times during the same period [24]. It should be mentioned that the new Ambient Air Quality Directive (AAQD) will aim to reduce air pollution in the EU to zero air pollution by 2050. To achieve this, stringent guidelines will be imposed, such as that of the annual limit of PM2.5. There are significant changes afoot in the EU when it comes to air quality.