This study utilized data from the Environmental Trace Gases Monitoring Instrument (EMI), the first Chinese satellite-based ultraviolet-visible spectrometer, to investigate global air quality changes during the COVID-19 pandemic in early 2020. Despite initial challenges with the instrument's spectral quality, algorithm optimizations enabled the retrieval of global gaseous pollutants such as nitrogen dioxide (NO2), sulfur dioxide (SO2), and formaldehyde (HCHO). The research found a significant drop in NO2 levels, correlating with lockdown measures implemented in various cities worldwide. Variations in HCHO levels indicated the dominance of anthropogenic sources of volatile organic compounds (VOCs) in some areas and natural sources in others. Analysis of NO2 changes relative to GDP highlighted the pandemic's varying impacts on different economic sectors across different countries.
