COVID-19 Pandemic as an Environmental Health Indicator: Lessons Learned from Air Pollution Changes and Climate Implications

The most crucial environmental issue threatening public health is air pollution, which is strongly associated with respiratory, cardiovascular, and infectious diseases. Increased concentrations of air pollutants, particularly from industrial activities, fossil fuel combustion, and transportation, have become a major global concern. Fine particulate matter emitted from diesel vehicles, biomass burning, and coal combustion has been identified as one of the most important contributors to adverse health outcomes. Previous studies have demonstrated that meteorological conditions and air pollutant concentrations may influence the transmission dynamics and severity of respiratory viral infections, including COVID-19. The COVID-19 pandemic provided a unique global-scale environmental experiment by temporarily reducing anthropogenic activities, including transportation and industrial processes, through lockdown measures. These restrictions resulted in short-term improvements in outdoor air quality and reductions in greenhouse gas emissions in many regions. However, these temporary improvements also highlighted the need for long-term structural strategies rather than short-term reductions in human activities to mitigate climate change. In this review, the interactions among air pollution, climatological parameters, and COVID-19 transmission are critically evaluated, and the impacts of COVID-19-related lockdown measures on outdoor air quality are summarized. Furthermore, the potential implications of the pandemic experience for future environmental health strategies and climate change mitigation policies are discussed. The findings of this review provide valuable insights into the relationship between human activities, environmental quality, and public health, emphasizing the importance of integrated approaches to address future environmental challenges.