Exploring the Interruption-Recovery Pattern of Air Pollutants During the COVID-19 Pandemic in Southern Brazil: An Analysis of the New Normal

This study investigated the interruption-recovery pattern of air pollutants (O₃, PM_2.5 and PM₁₀) during and after the COVID-19 pandemic in Southern Brazil using machine learning models. The results showed that 2020 was an atypical year for air pollution levels due to restriction measures. However, we also found that 2021 was not a definitive year for the assessed air pollutants in the region but rather a transitional year. It was only in 2022 that the pollutant levels returned to usual levels in the region. In this sense, our findings suggest that the levels observed in 2022 can be considered the "new normal" for air pollutants in the region. Furthermore, we found that O₃ levels decreased significantly and were sustained and further decreased in 2022, while PM_2.5 and PM₁₀ levels showed a reversed but similar trend with a slight increase in concentrations from 2020 to 2021 and again from 2021 to 2022. Overall, this study provides valuable insights into the impacts of COVID-19 on air pollution levels and highlights the need for continued efforts to improve air quality in the region.