In this feature article, the air quality variation was estimated in three cities of Asian countries that enforced the self-quarantine and the city lockdown during the initial COVID-19 pandemic. The data assessment based on the actual measurements from the air pollution monitoring stations of each city clearly showed a quantitative reduction of PM2.5 and NO2 during the initial COVID-19 pandemic period. The reduction of potential health effect for 10-year-old children in each city due to the reduced PM2.5 during the self-quarantine was also quantitatively assessed. Although it was only temporary, the fact of the improvement in air quality under the COVID-19 measures gives us great significance in the future environmental policy. Perhaps the COVID-19 has given us an example of an answer to why we should improve air quality. Therefore, we should not only try to overcome the current situation of the COVID-19 pandemic, but at the same time, seriously consider the new eco-lifestyle that we must pursue after the end of COVID-19 pandemic. © 2021 Japan Association of Aerosol Science and Technology. All right reserved.
