How COVID-19 affected global air quality?

The years 2020-21 are some of the most challenging years experienced by humankind. While the people of Earth recover from the hard blow of COVID-19, they also witnessed several large-scale wildfires. As a result, we observed both the positive and negative impacts on the ambient air quality. The wildfire occurrences severely deteriorated the air quality. In contrast, country-wide complete and partial lockdowns accounted for cleaner air in some regions. 

The lockdown provided a clean window to air and atmosphere for self-cleansing. Several government authorities took the opportunity to work on their clean air programs. As a result, the use of alternative monitoring systems like low-cost sensor-based devices has become more common. Moreover, the air quality data collected over the years helped in conducting several studies. Scientists & researchers used the data to understand the impacts of lockdown on air quality and establish the interrelationship between air pollution, pollutants, and COVID-19. However, it indirectly also questioned the efficiency of current monitoring networks.