# Changes of Air Pollution between Countries Because of Lockdowns to Face COVID-19 Pandemic
## 3 Results and Discussion
### General Observations
[PERSON] and [PERSON] [65] analyzed the variations in the concentration of air pollutants between the year with restriction measures and pre-lockdown periods. They observed that the concentrations of PM\({}_{2.5}\), PM\({}_{10}\), and NO\({}_{2}\) significantly decreased, whereas SO\({}_{2}\) slightly \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Average Variation \% of Air Pollutant Values from January 2019 to March 2022**} \\  & & \multicolumn{6}{c}{**Compared with Baseline Period (2015–2018)**} \\ \hline
**Geoeconomic** & & & & & & & \\
**Region** & **Country** & **CO** & **NO\({}_{2}\)** & **SO\({}_{2}\)** & **O\({}_{3}\)** & **PM\({}_{2.5}\)** & **PM\({}_{10}\)** \\ \hline Asia & China & \(-49.68\) & \(-153.77\) & \(-98.25\) & \(-87.26\) & \(17.10\) & \(20.89\) \\  & India & \(-105.90\) & \(-39.30\) & \(-17.20\) & \(-24.50\) & \(12.40\) & \(13.10\) \\  & Israel & \(-122.10\) & \(12.30\) & \(-13.80\) & \(33.30\) & \(-8.20\) & \(-18.80\) \\  & Japan & \(-24.50\) & \(-15.00\) & \(-37.50\) & \(-1.80\) & \(-12.30\) & \(-16.10\) \\  & South Korea & \(-26.70\) & \(-20.40\) & \(-64.70\) & \(5.90\) & \(-1.30\) & \(-12.90\) \\ \hline North America & Canada & \(-655.50\) & \(-13.80\) & \(-193.70\) & \(4.50\) & \(-27.30\) & \(-8.10\) \\  & USA & \(-17.10\) & \(-7.60\) & \(-107.30\) & \(12.10\) & \(-4.30\) & \(-2.30\) \\ \hline South America & Brazil & \(-48.50\) & \(-10.90\) & \(-89.00\) & \(4.70\) & \(8.60\) & \(-7.70\) \\  & Chile & \(4.30\) & \(-15.80\) & \(-24.40\) & \(6.70\) & \(8.60\) & \(16.70\) \\  & Colombia & \(-46.10\) & \(19.00\) & \(18.50\) & \(-29.30\) & \(-12.40\) & \(-46.30\) \\ \hline Europe & Croatia & \(0.00\) & \(-8.10\) & \(-60.10\) & \(-0.02\) & \(-11.90\) & \(5.70\) \\  & France & \(-3471.80\) & \(-17.90\) & \(-33.50\) & \(3.60\) & \(-11.40\) & \(-1.80\) \\  & Germany & \(-135.00\) & \(-11.50\) & \(-92.20\) & \(9.80\) & \(-29.60\) & \(-1.60\) \\  & Netherlands & \(10.50\) & \(-16.00\) & \(-16.30\) & \(8.20\) & \(-4.50\) & \(-7.70\) \\  & Poland & \(-9.60\) & \(2.90\) & \(-24.30\) & \(27.30\) & \(7.00\) & \(-16.80\) \\  & Spain & \(-73.80\) & \(-22.20\) & \(-18.50\) & \(4.20\) & \(3.90\) & \(5.50\) \\  & Turkey & \(-27.60\) & \(-9.40\) & \(-4.40\) & \(-20.40\) & \(-39.50\) & \(-115.00\) \\  & United Kingdom & \(-19.40\) & \(-23.40\) & \(-26.20\) & \(7.20\) & \(-4.90\) & \(-7.00\) \\ \hline Oceania & Australia & \(-59.80\) & \(-153.70\) & \(-98.30\) & \(-87.30\) & \(17.10\) & \(20.90\) \\ \hline \hline \end{tabular} Note: For details see Supplementary Materials.  
\end{table} 
Table 2: Main effects of the containment policy of lockdown to face COVID-19 on average levels of air pollutants between selected countries worldwide. reduced owing to the contribution of power plants. [PERSON] et al. [100] investigated the global changes in the concentration of air pollutants because of lockdown measures. The results confirm other studies indicating a decrease in the NO\({}_{2}\) and PM\({}_{2.5}\) concentrations, and an increase in the O\({}_{3}\) concentration. Hence, the measures of control applied by countries to contain the negative impact of the COVID-19 pandemic can reduce the sources of air pollutants that contribute to release greenhouse gas emissions into the atmosphere. In particular, since the major sources of SO\({}_{2}\) and CO are the combustion of fossil fuels containing sulfur and carbon, particularly from power stations burning coal and vehicles [101], and for NO\({}_{2}\) and tropospheric O\({}_{3}\) the major sources are vehicle emissions and industrial processes [102], the restriction policies of lockdown to face the COVID-19 pandemic can reduce the pollutant concentrations mainly associated with the consequential limitations in transportation.